* GB785373 (A)

Description: GB785373 (A) ? 1957-10-30

Process for the preparation of heterocyclic compounds

Description of GB785373 (A)

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PATENT SPECIFICATION ^ Date of Application and filing Complete Specification: Dec 14, 1954. No 36169/54. Application made in Netherlands on Dec 23, 1953. Complete Specification Published: Oct 30, 1957. Index at acceptance:-Class 2 ( 3), B 4 (A 1; D 4; E; H; M). International Classification:-CO 7 d. COMPLETE SPECIFICATION 55,373 Process for the preparation of Heterocyclic Compounds We, ORGANON LABORATORIES LIMITED, a British Company, of Brettenham House, Lancaster Place, London, W C 2, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to the preparation of heterocyclic compounds with two heteroatoms, and to derivatives thereof.

For the preparation of heterocyclic compounds use is often made of bifunctional compounds, which are allowed to react with, for example, other compounds that are bifunctional or not, for the formation of ring systems. A process has been discovered for the preparation of heterocyclic compounds with two heteroatoms, characterised in that a comR \NH 2 pound of the formula R 1 OC-C-R,, wherein 20 R 1 is an alkyl group and R 2 is H, an alkyl-, aryl or aralkyl group, is allowed to react with a compound of the formula: /x \g H 1112 wherein R represents an aliphatic, aromatic or alicyclic group and X is O S, NH or NR. (R, is an alkyl-, aryl-, or aralkyl group) and after completion of the reaction, the heterocyclic compound is isolated. A reaction which corresponds with the following scheme takes place: OCH 242 + R 1 OH in which R, R,, R 2 and X have the meanings assigned above. The present invention also comprises, as new chemical substances, compounds of the general formula: 0N ' in which R represents -(CH 2)6 or and R 2 represents H, an alkyl-, aryl or aralkyl group. It is surprising that the alkoxyacetylenes react so easily and participate in the ring with only one of the acetylene atoms. The reaction may be allowed to take place in a solvent for the starting product, for instance dioxane; but preferably the process is performed without making use of a solvent In that case the starting substances are brought to reaction by refluxing After completion of the reaction the final product is obtained either by fractional distillation or direct by crystallisation on cooling the reaction mixture. These compounds can easily -be converted into picrates. The method according to the invention is eminently suitable for the preparation of azoles, azines and of the 1-N-substituted compounds, some of which are already known These wellknown compounds, however, have been synthesised in a different way. As bifunctional compounds we may use for instance amino-alcohols, diamines and aminothioalcohols, such for instance as ethanolamine,so 0112p ( 11 11 v^ -' Able awry 2 aminopropanol 1, orthoaminophenol, ethylene diamine, orthophenylene diamine, mercaptoethyl amine, ortho-aminobenzyl alcohol, 3-aminopropanol-1, 1-monododecyl amino-2-aminoethane The diamines used as starting product may be substituted at one of the nitrogen atoms by an alkyl-, aryl-, or aralkyl group so that after reaction for instance N-substituted imidazoles and N-substituted diazines and derivatives thereof are obtained from them.

As alkoxyacetylene compound there may be used for instance methoxyacetylene, ethoxyacetylene, 1-ethoxy-2-ethyl acetylene, 1-ethoxy2-phenylacetylene, 1-ethoxy 2 c naphthylacetylene, 1-ethoxy-2-nonakosylacetylene and propoxyacetylene These alkoxy derivatives of acetylene can for example be prepared according to Van Doro Arens and Stephenson, Rec. Trav chim Pays Bas 70, 289 ( 1951). The method forms a new route for the preparation of heterocyclic compounds with five, six or more atoms such as the diazepines and oxazonines. This method may be used among other things for the preparation of heterocyclic compounds substituted in the 2-position, namely the 2-substituted oxazines having more than 7-C atoms, which have not yet been described in literature so far, and which accordingly fall within the scope of the invention Also by the reaction of ethoxyacetylene with 3-aminopropanol-l; 2-methyl 5: 6 dihydro-oxazine1: 3 is formed; boiling point: 40-45 C ( 43 mm), n DJ 6: 1 4446 The picrate has a m p. of 100-102 C. The compounds prepared according to the invention are important as intermediate products for the preparation of medicines, as a medicine itself, as softening agents for textiles, emulsifiers, flotation aids, asphalt additives, fungicides or as insecticides. Thus for instance 2-methyl-1-dodecylimidazoline can be prepared by allowing ethoxyacetylene to react with 1-mono-dodecylamino-2-aminoethane, which is bacteriostatically active, as well as many imidazolines with the structural formula: CH 2 N in which R 4 and R, each represent a hydrocarbon residue, for example methyl, ethyl, amyl, decyl, tetradecyl or hendecyl groups, which compounds can be prepared according to the method concerned The well known vasodilator and hypotensive substance, 2benzyl-2-imidazoline can be prepared from ethylene diamine and 1-ethoxy-2-phenyl acetylene according to the process of the invention in a simple way This method also enables preparation of the well-known vaso 60 constrictor, 2-( 1-naphthyl methyl)-2-imidazoline, from ethylene diamine and 1-ethoxy-2-anaphthyl acetylene 2-Triakontylimidazoline, obtained by reaction of ethylene diamine and 1 ethoxy 2 nonakosylacetylene, is highly 65 poisonous for the red-coloured spider, which is frequent in tropical areas, and is used as a pesticide for it 2-Heptadecyl-2-imidazoline is used as foliage fungicide for the control of apple scab and cherry leaf spot The 2-alkyl 70 substituted -2 imidazolines exhibit surfaceactive properties. The following examples illustrate the invention. EXAMPLE I 75

2-methyl-oxazoline. A mixture of 5 7 gmi ( 0 093 mol) of freshly distilled ethanolamine and 6 5 gm ( 0 093 mol) of ethoxyacetylene is refluxed on an oil-bath at 100 C Boiling stops after some 30 80 minutes, because the boiling point of the reaction mixture has risen The smell of ethoxyacetylene is no longer observable The reaction mixture is now subjected to a fractionated distillation at 700 mm of Hg 85 pressure After the first distillate, which contains ethanol, 3 5 gm of 2-methyloxazoline are obtained with a m p of 100-107 C; (most of which distils at 106-107 C) The smell agrees with that of pyridine With a 90 cold alcoholic solution of saturated picric acid the picrate of 2-methyl oxazoline is formed, which melts at 158-161 ' C If this compound is left to stand in the mother-liquor it dissolves again and forms the picrate of fl 95 acetoxy-ethylamine. EXAMPLE II. 2: 4-dimethyloxazoline. A mixture of 6 gm of ethoxyacetylene and 6.25 gm of dialaninol ( 2-amino-propanol-1) is 100 refluxed to boiling After some 4 hours the boiling point of the liquid no longer rises. The reaction mixture is left to stand overnight, after which it is subjected to a fractionated distillation at 700 mm of Hg 105 pressure The first fraction is caught at 5574 C and amounts to O 25 gm The second fraction amounts to 2 25 gm and has a boiling range of 74-870 C This fraction mainly consists of ethanol Distillation is continued 110 in vacuo and between pump and distillation apparatus an extra condensed collecting apparatus is mounted At 300 C and 35 mm of Hg-pressure 3 75 gm of 2: 4-dimethyl oxazoline with n D 2 a= 1 4220 distils off The last 115 part of this fraction, which is collected separately, is the pure 2:4-dimethyloxazoline with n D 2 = 1 4246 The compound smells something like 2-picoline The residue amounts to 1 25 gin The extra condensate collecting 120 785,373 78 '5,; 73 3 ' apparatus contains 2 gm of liquid with N 2 ' = 1.4064, mainly consisting of 2: 4-dimethyloxazoline The resulting picrate melts at 130 -135 C and decomposes on recrystallising. EXAMPLE III. 2-methylimidazoline (lysidine). A mixture of 7 gm of freshly distilled ethylene diamine and 5 75 gm of ethoxyacetylene is brought to reaction by heating to boiling The reaction is completed by boiling the mixture at '1000 C on an oil-bath for 30 minutes On cooling, the 2-methyl imidazoline crystallizes, after which the crystals are separated from the mother-liquor by filtration Another second quantity of crystals is obtained from the mother-liquor by evaporating in vacuo. The total yield amounts to 3 5 gm of substance with a m p of 98 '1010

C The picrate formed by reaction with a saturated alcoholic solution of picric acid melts at '197-2010 C. After recrystallisation from water, the m p of the picrate amounts to 200-203 C (not corrected). EXAMPLE IV. 2-methylbenzimidazole. A mixture of 3 gm of ethoxyacetylene and 4.6 gm of orthophenylene diamine is refluxed at boiling temperature for 8 hours To the resulting homogeneous solution, once this is cooled are added '10 cc of low-boiling petroleum ether, as a result of which 2 5 gm. of unaltered orthophenylene diamine crystallise The mother-liquor which is left after the orthophenylene diamine has been filtered off, is evaporated to dryness and the resulting residue is left to itself Part of this solidifies. This is filtered and recrystallised from water. The yield amounts to 1 gin of 2-methylbenzimidazole with a m p of '173-175 C. EXAMPLE V. 2-methylthiazoline. 6.6 gm of mercaptoethylamine and 6 gm. of ethoxyacetylene are refluxed for 2 hours. The reaction mixture is then subjected to a fractionated distillation in the same manner as described in Example I, a first 'fraction of 1.5 gm with boiling point of 75-76 C. being separated, which fraction mainly consists of ethanol The second fraction of 3 75 gm contains 2-methylthiazoline, a liquid smelling of pyridine with a boiling point of 50-53 C at 30 mm of Hg pressure In the distillation apparatus 3 75 gin of residue are left behind in the form of a viscous brown Elementary analysis: C 5 H 9 ON Found Calculated n D 26 1 4449 oil The condensed collecting apparatus between vacuum pump and apparatus contains 2 gm of clear liquid, mainly ethanol. Redistillation of the second fraction yields a liquid with boiling point 50 C at 28 mm. of Hg-pressure and n D 24 = 1 5128 The picrate has a m p of '169-170 ' C. EXAMPLE VI. 2-methyl-'1-dodecylimidazo Iine-2. On an oil-bath of 1000 C 5 gm of ethoxyacetylene and 15 4 gm of '1-mono-dodecylamino-2-aminoethane are refluxed for 2 hours. After this the reaction mixture is subjected to a vacuum distillation, as a result of which 1.71 gm of 2-methyl-'1-dodecylimidazoline are obtained as an oil with boiling point 1701750 C at 4 mm of Hg-pressure.

EXAMPLE VII. 2-propyl-imidazoline-2. A mixture of 2 gm of anhydrous ethylene 75 diamine and 4 9 gm of '1-ethoxy-2-ethylacetylene are refluxed on an oil-bath of 1200 After 2 hours the reaction is completed The reaction mixture is then subjected to a fractionated vacuum distillation; whereby the 2 80 propyl-imidazoline-2 distils off at '135-140 C and 25 ' mm of Hg-pressure and is collected as a colourless liquid which solidifies on cooling The yield amounts to 2 01 gm of 2 propyl-imidazoline-2 with a m p of 34-35 85 C The picrate melts at 128-129 C. EXAMPLE VIII. 2-benzyliinidazoline-2. 6 gm of ethylene diamine and 16 gm of 1-ethoxy-2-phenyl acetylene are heated in a 90 sealed tube for 2 hours at '1500 C The reaction mixture is then subjected to a fractionated vacuum distillation At 120 1300 C. and 4 mm of Hg-pressure 3 9 -gm of pure 2-benzylimidazoline-2 distils off which, after 95 cooling in the receiver, crystallise The m p amounts to 66-68 C The picrate melts at 145-146 C. EXAMPLE IX. 2-Methyl- 12-dihydro-oxazine-1: 3 100 A mixture of 3 75 gm of 3-aminopropanol-1 is heated under reflux at 1100 C. for 3 hours with 3 0 gm of ethoxy-acetylene. Subsequently the mixture is distilled The fraction that distils at 133 '138 -C is dis 105 tilled once again, as a result of which 3 gm. of 2-methyl-A'-dihydro-oxazine-1: 3 with a boiling-point of 133-133 5 C, are obtained. C 59 44, 5953 %; H 9 33, 9 29 %; N 13 7, '136 % 60.58 915 1413 The melting point of a picrate prepared to 103 5-1040 C. with an ethereal solution of picric acid amounts 785,373 EXAMPLE X. 2-Methyl-3:4:5: 6-tetrahydropyrimidine. 4 gm of ethoxy-acetylene is heated under reflux with 5 gm of 1:3 diaminopropane At 40 C the reaction takes place Then the mixture is heated at 1100 C for another 30 minutes Subsequently the reaction product is distilled in vacuo The yield amounts to 6.46 gm of crystalline 2-methyl-3:4:5: 6tetrahydropyrimidine with a boiling point of 99-102 C at 7 mm of Hg-pressure. The picrate melts at 153-153 50 C. EXAMPLE XI. 2-Methyl-4: 5-benzo-oxazine-1: 3. A mixture of 2 44 gm of o-amino-benzylalcohol and 3 16 gm of ethoxy-acetylene is heated at the boiling-point for 8 5 hours while refluxing The reaction mixture is subsequently subjected to a vacuum distillation, whereby 0 725 gin of thick oil are obtained This oil has a boiling range of 94-115 ' C at 3 mm.

of Hg-pressure The picrate prepared herefrom melts at 145-148 C The yield amounts to 2 19 gm of 2-methyl-4:5-benzooxazine-1 l: 3-picrate. EXAMPLE XII. 2-Methyl-5: 6-dihydro-1: 3-thiazine. A mixture of 3 0 gm of ethoxy-acetylene and 4 50 gin of 1-thiol-3-aminopropane is boiled under reflux until the thermometer, placed in the liquid, no longer shows any increase of the boiling point Then the reaction mixture is distilled at usual pressure The desired compound distils at '170-176 C The yield amounts to 3 5 gm of 2-methyl-5: 6dihydro-l: 3-thiazine The melting-point of the picrate is 135-136 C. EXAMPLE XIII. 2-( 1-Naphthylmethyl)-2-imidazoline. 2 9 gm of ethylene diarnine and 9 8 gm. of 1-ethoxy-2-( 1-naphthyl)-acetylene are heated in a sealed tube at 1500 C for 2 hours Then the reaction mixture is subjected to a fractional vacuum distillation 7 1 gm of 2-( 1naphthylmethyl)-2-imidazoline distil at 4 mm. of Hg-pressure and 120-140 C After cooling this compound crystallises in the receiver. The melting-point amounts to 133-134 C. EXAMPLE XIV. 2-heptadecyl-2-imidazoline. 2.9 gm of anhydrous ethylene diarnine and 14.7 gin of 1-hexadecyl-2-ethoxy-acetylene are heated under reflux on an oil-bath of 1200 C After two hours the reaction is complete. Then the reaction mixture is subjected to a fractional vacuum distillation whereby the desired compound is collected as a colourless liquid which coagulates on cooling The yield amounts to 8 2 gin of 2-heptadecyl-2-imidazoline with a melting-point of 94-95 C. EXAMPLE XV. 2-methyl-4: 5: 6: 7-tetrahydro-1: 3-diazepine. A mixture of 2 10 gm of 1: 4-diaminobutane is heated with 2 10 gm of ethoxy acetylene to 750 C, after which the reaction occurs spontaneously Subsequently the mixture is heated for another 30 minutes at 1200 C., after which it is distilled in vacuo, whereby 1.6 gm of viscous liquid are obtained with a boiling-range of 150-190 C which, on storage, decompose. The picrate recovered in ethereal medium showed a melting point of 1320 C in nitrogen atmosphere. EXAMPLE XVI. 2-methyl-4: 5: 6: 7: 8: 9-hexahydro-1: 3oxazonine. 7.5 gm of aminohexanol, with a boilingpoint of 225-230 at 760 mm is heated under reflux with 9 gm of ethoxy-acetylene at C for 7 hours The

mixture is subjected to a fractional distillation, whereby 1 gtn of a mixture of ethanol and ethoxy-acetylene and then 4 5 gm of ethoxy-acetylene distils Subsequently the residue is distilled in vacuo at 2 mm The fraction that has a boiling-range of 116-125 C contains the 2-methyl-4: 5: 6: 7: 8: 9-hexahydro-1: 3-oxazonine.

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* GB785374 (A)

Description: GB785374 (A) ? 1957-10-30

Improvements in or relating to liquid fuel burners

Description of GB785374 (A)

PATENT SPECIFICATION Inventors: JOHN EDWARD SHERLOCK and CECIL GEORGE THORPE Date of filing Complete Specification: Dec 23, 1955. Application Date: Dec 29, 1954. 785,374 No 37573154. 19 N Complete Specification Published: Oct30, 1957. Index at acceptance:-Class 75 ( 1), TA 8. International Classification:-F 23 d. COMPLETE SPECIFICATION Improvements in or relating to Liquid Fuel Burners We, THE BRITISH THERMOSTAT COMPANY LIMITED, a British Company, of Teddington Works, Windmill Road, Sunbury on Thames, Middlesex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to liquid fuel burners and, in particular, to a burner employing a trough

for vaporizing the liquid fuel and designed to operate efficiently over a substantially wide range of burning which makes it adaptable for use with thermostaticallyoperated flow-metering devices. According to the invention there is provided a liquid fuel burner having a vaporizing trough and a pilot or low-fire burner, in which an outwardly and upwardly inclined burner pan is formed as a peripheral extension of the vaporizing trough and serves to heat the latter by conduction while the pilot or low-fire burner is so designed that it shields the central portion of the burner pan from direct radiation of the flame in the main burner so that under intermediate or high-fire conditions the temperature of the vaporizing trough is maintained by conduction at a value sufficient only to allow a limited amount of vaporization to take place. The construction and operation of an embodiment of the invention will now be described with reference to the accompanying drawing: During the operation of low-fire burning, oil is metered through an inlet 1 into a shallow vaporizing trough 2 and primary air which flows through a centre sleeve 3 is deflected by a burner cone 4 to pass through a perforated member 5 that is arranged substantially horizontally and immediately above a peripheral extension 6 of the vaporizing trough The members 4 and 5 form a hollow member known as the pilot or low-fire burner The peripheral extension 6 (to be called lPrice 3 s 6 d l a burner pan) is arranged on a slightly outwardly and upwardly inclined plane and extends outwardly to a cylindrical vertical wall 7 The surface of the burner pan 6 immedi 50 atey below the perforated member 5 is heated by radiation from the combustible mixture that burns at the holes of the perforated member during low-fire operation, the vaporizing trough 2 being heated partly by radia 55 tion and partly by conduction from the burner Dan The burner pan is therefore maintained at a high enough temperature to ensure immediate vaporization of additional fuel that would flow beyond the vaporizing 60 trough if and when the fuel flow were increased to give intermediate or high-fire operation It is to be noted that the perforations in the member 5 do not come directly above the vaporizing trough 65 When the flow of oil is increased the combustion is transferred beyond the perforated member 5 to the larger space within the burner Under high-fire or intermediate-fire conditions, primary air enters the centre 70 sleeve 3 and flows through the perforations in the member 5 to mix with oil vapour which is emitted from the vanorizing trough. This mixture flows into the larger combustion chamber bounded by the outer cylin 75 drical wall 7 and is fed with additional primary air from holes 8 that are provided in the wall 7 This additional air mixes with the vapour that is also being generated from the high fractions

on the surface of the inclined 80 burner pan 6 The burner pan is now heated by radiation from the flame inside or at the outlet of the chamber The design of the pilot or low-fire burner is so arranged that it shields the centre of the burner pan from 85 direct radiation of the flame in the chamber, so that under intermediate or high-fire conditions the temperature of the shallow vaporizing trough is maintained by conduction at a value sufficient only to allow a limited 90 amount of vaporization to take place. It will be appreciated, therefore, that a temperature gradient occurs along the radial length of the burner pan and that vaporization occurs at reasonably low and gradually increasing surface temperatures, which eliminates the possibility of "cracking" of the oil which would occur if the liquid fuel contacted an extremely hot surface. The combustion chamber is bounded as already stated by the cylindrical wall 7 which is perforated at 8 for the purpose of supplying primary air according to the burning conditions The cylindrical member 7 terminates in the form of an annular deflector plate 9 to complete the construction of the combustion chamber and further holes 10 or slotted airways are provided at or near to the junction of the cylinder and deflector to provide a supply of secondary air under highfire conditions. For intermediate firing conditions the flame is maintained within the combustion chamber with primary air fed only from the lower holes 8 of the outer cylinder During high-fire operation primary air is fed to the vapour by the majority of the holes in the cylinder, with the exception of those designated 10 in the uppermost region which provide secondary air to the flame which burns partly inside the chamber and to a greater extent above the mouth of the deflector plate 9. With the arrangement described above it has been establsihed that the low-fire consumption can be as low as 4 % of the maximum high-fire consumption This makes the burner particularly suitable for thermostatic control in applications such as hot water storage systems where it is essential to have a high input rating for initial heating and a low maintenance input to balance the rela 40 tively low insulation losses when the storage tank is up to its working temperature.

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* GB785375 (A)

Description: GB785375 (A) ? 1957-10-30

Improvements in or relating to the manufacture of flat wire rope

Description of GB785375 (A)

PATENT SPECIFICATION 7851375 Date of filing Complete Specification: Jan 17, 1956 Application Date: Feb 5, 1955. No 3493/55. y Complete Specification Published: Oct 30, 1957. ptance:-Class 109, D( 1 F: 1 K: 2 B 1 A 2: 2 B 5). Classification:-D 07. COMPLETE SPECIFICATION Improvements in or relating to the 'Manufacture of Flat Wire Rope We, R HOOD HAGGIE & SON L Im ITED, of Willington Quay, Wallsend-on-Tyne, England, a British Company, and Jo HN EDWARD SMITH, of 49, Beckenham Avenue, East Boldon, in the County of Durham, England, a British Subject, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to the manufacture of flat wire rope. Braided flat wire ropes formed by hand from wire ropes are known. The object of the invention is to provide simple means for the manufacture of flat wire rope by machine which may be applied to existing rope manufacturing machinery with the minimum of alteration; and have the additional advantage of even tension on the individual strands throughout the length of the flat rope. According to the present invention there is provided means for the manufacture of flat wire rope comprising a forming head adapted to be mounted in a wire rope making machine and carrying, circumferentially spaced around its axis and equidistant therefrom, at least three rotatable ferrules each having an even number of bores symmetrically arranged about the axis of the ferrule and adapted to receive the strands to be formed into the rope, and flat-spaced pressure blocks

through which the formed rope passes prior to its being wound on the uptake capstan of the machine. The invention will now be described by way of example with reference to the accompanying drawings which shows it applied to a known form of wire rope making machine. In the drawings:Figure 1 is a perspective view from the front or leading side of the forming portion of a typical round wire rope making machine with the means according to the invention appliede lPr X Figure 2 is a similar view to Figure 1 but taken from the rear or outlet side of the machine. Figure 3 is a front elevation of the forming 50 head. Figure 4 is a section on the line IV-IV of Figure 3. Figure 5 is a plan view of a section of the flat rope produced by the means according to 55 the invention. Figures 6 to 10 are cross sections respectively on the lines VI-VI, VII-VII, VIIIVIII, IX-IX, X-X of Figure 5. Referring more particularly to the draw 60 ings, 1 is the forming head which is fitted in place of the lay-plate of the machine, and consists in a circular steel plate of the same diameter as that of the said lay-plate Three equally spaced bores at the same radial dis 65 tance from the centre of the forming head 1 are formed in the latter at la, lb, lc, and in these bores are mounted on ball or roller bearings 2 three hardened steel flanged ferrules 3 each having formed therein two 70 holes 3 a 3 b arranged symmetrically about the axis of the ferrule along a diametral line, the flanges of the ferrules being arranged on the leading front face of the forming head, to hold them against axial movement 75 Flat-faced pressure blocks 4, 5 are substituted for the usual hemispherical closing or pressure blocks used on the machine for the making of ordinary round rope. Three double strands of wire rope, 6, 7, 8 80 are led in the usual manner from the strand bobbins (not shown), and each pair of strands is threaded through a ferrule 3, thence under the flat-faced pressure blocks 4, 5, and finally to the uptake capstan (not shown) The 85 initial effect of the twisting of the three double strands is to produce a round threestrand rope as at A with the difference that the strands are double, but as a result of its being passed between the pressure blocks 4, 90 5, the rope is laid flat as at B in two layers of strands with a row of two strands now above Index at accej International a row of four strands, and then a tow of four strands above a row of two strands For example, referring to Figures 5 to 10 and considering the length of rope indicated at Z in Figure 5, at the start VI-VI of this length a row of two strands 6, lies above a row of four strands 7, 8, at VII-VII the strands 6 in the upper row have been joined by the pair of strands 8 which were on the right hand side of

the lower row, at VIII-VIII the strands 6 of the first upper row (Fig 6) have now passed to the lower row, and the two strands 7, which constituted the lower row of Figure 7, have now moved into the upper row; and so on in cyclic order up to the end of the length Z The lower row throughout the particular pitch length VII-VII to X-X consists of two strands only During the next equivalent pitch length this arrangement is reversed i,e the upper row consists of two strands only. The resulting flat rope may be used for slings, for example, in the same way as are braided ropes, but with the advantage over the latter that owing to the even tension in the individual strands, they are of uniform strength throughout.

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* GB785376 (A)

Description: GB785376 (A) ? 1957-10-30

Improvements relating to foam-generating apparatus

Description of GB785376 (A)

COMPLETE SPECIFICATION Improvements relating to Foam-Generating Apparatus We, THE PYRENE COMPANY LIMITED, a British Company, of Great West Road. Brentiord, Middlesex, do hereby declare the invention for which we pray that a patent may be granted to us, and the method bv which it is to be performed. to he particularly described in and by the following statement: Tbis invention relates to that kind of foan-generating apparatus in which air is entrained by a jet or jets of a flowing solution of a

foam-stabilising compound in water and the mixture forms foam in flowing through a tube to a nozzle at or constituted bv the open end of the tube. In sudi apparatus the foam tube usually consists of two distinct parts, namely a cylindrical or substantially cylindrical part and a contracting part terminating in the nozzle. The mixture of air and liquid is formed into foam in travelling through the first of these parts, which may eonveniently be called the foamdeveloping chamber. The effectiveness of the chamber in developing foam appears to increase with its size, and for this reason this chamber has always been of considerable length in relation to its diameter. We have now found that it is possible materially to shorten the length of the apparatus and yet to ensure that it will project foam of good quality as a jet of good range and good characteristics. In designing an apparatus of the kind in question it is first necessary to know the intended capacity, that is to say, the volume of liquid to be supplied to the apparatus under a given pressure per minute and the volume of foam to he producked. The ratio of the volume of foam to that of water is known as the expansion and in part depends on the nature of the foam-stabilising compound. The foam must emerge through the outlet nozzle at high enough velocity to travel through a satisfactory distance, and it will readily be appreciated that this velocity and the volume of the foam produced together determine the cross-sectional area of tbe outlet nozzle, i.e. the smallest such area in a nozzle of non-nniform cross-section, whereas the volume of the liquid determines the total cross-sectional area of the orifice or orifices through which the liquid flows as a jet or jets. An essential featnre of the invention is that the foam-developing chamber is much shorter and of larger diameter than the chambers in previous apparatus designed to produce the same volume of foam. The use of such a short chamber is possible. we find if the chamber contains a gauze or other obstruction to the flow so as to increase the mixing of the liquid and air. The foam-developing chamber must have a minimum volume, even though there is an obstruction in it, if foam of good quality is to be formed. The volume can, however, be less than that in the apparatus used hitherto, partly perhaps because some mixing of the liquid and air occurs as a result of the radial expansion permitted bv the relativelv large diameter of the chamber. If this volume is too high, the desired reduction in the length of the apparatus cannot be obtained. The contracting part must not be too long, since otherwise the desired reduction in length is again lost. Since, however, the liquid loses

velocitv in the short wide chamber it is essential to recover some of this velocity, and therefore there is a minimum length for the contracting part. The recovery in velocitv is increased if, as is preferred, the contracting part is internally convex so as to eause the foam passing through it to accelerate uniformly. Raving regard to these requirements the shape of the foam tube may be defined by the statements that the ratio of the mean cross-sectional area of the foamdeveloping chamber to the cross-sectional area of the nozzle must be between 2.25:1 and 5:1; the ratio of the square of the length of the foam-developing chamber to the cross-sectional area of the nozzle must be between 11.5:1 and 26:1; and the length of the contracting part must be between 1/3 and of the overall length. By the overall length we mean the distance from the tip of the nozzle to the point of emergence of the jet or jets into the tube. The preferred ratio of the square of the length of the chamber to the cross-sectional area of the nozzle depends on whether the apparatus is fed with a pre- mixed solution of foam-stabilising compound in water or whether the compound is induced into the apparatus by the water stream. In the latter case some mixing of the compound and water takes place in the foam-developing chamber, and accordtingly it is desirable to make this ratio greater than when the solution is premixed, suitable figures being between 11.5:1 and 20:1 when the solution is premixed, and between 15.5:1 and 26:1 when the compound is induced by the water stream. The obstruction in the foam-developing chamber may take various forms. Thus it may be a conical or frustro-conical gauze inserted in the chamber with its narrower end downstream, and arranged so that substantially all the liquid projected into the chamber impinges on the inner surface of the gauze. If a gauze is used, the liquid is preferably delivered into the foam tube as a number of parallel or substantially parallel iets of such radial distances from tbe asis of the tube that they must strike the gauze and that none passes direct to the outlet opening (if any) of the gauze. The obstruction may also consist of rods extending longitdinally through the chamber or even of a rib on the inner wall of the chamber. Some apparatus according to the invention will now be described with reference to the accompanying drawings, in which the three figures show axial sections through three apparatus. Theapparatus shown in Figure 1 comprises an end member 1 shaped to receive the end of a hose pipe 2 through which a pre-mixed solution of water and foamstabilising liquid is supplied under pressure. The forward end of the member 1 is threaded to receive a foam tube 6

having a shoulder 3. When the tube 6 is screwed home, an orifice plate 4 is held in position between the end of the member 1 and the shoulder 3. The plate 4 lies at a short distance in front of a bore 5 in the mem ber 1 through which the liquid stream arrives to strike the plate. A frusto-conical gauze 7 is fixed at its rear end inside the foam tube 6. This gauze stops just short of the end of the tube 6, which forms a circular discharge nozzle. The orifice plate has a set of orifices 9 all lying at a radial distance from the axis slightly less ilion the radins of the gauze 7 at its wider end. As shown. the orifices split the lionid stream up into substantially parallel jets indicated at 10, but if they are such that the jets converge slightly instead of being exactly parallel to one another, their centre lines should meet at a point beyond the forward end of the gauze. Because the liquid stream enters the space behind the plate 4 on leaving the bore 5, it is turbulent, and because of this the jets tend to diverge on issuing from the orifices. Openings R are made in the foam tnhe c to allow air to be entrained by the jets. The foam tube 6 comprises a substan- tially cylindrical foam-developing chamber extending from the line A, namely the point at which the jets of liquid emerge into the tube fi. to the line B where the tube begins to contract in diameter. The tube then has internally-convex contracting part extending from the line B to the tip of the nozzle. indicated by the line C. The contracting part is. as shown, of such a profile that the foam is forced to accelerate at a substantially constant rate in flowing to the outlet. If the foam were a trueliquid an ideal profile would be a logarithmic curve, but since the foam is somewhat elastic a slight deviation from a logarithmic curve will produce even better stream-lining. As illustrations of the reduction in size obtainable by means of the invention, a standard generator as constructed hitherto for converting 2 gallons of liquid into foam per minute is 9 inches long: a generator of the same capacity made as shown in Figure 1 is only 4 inches long and yet will project a rope-like jet through about 20 feet. As an example of the dimensions of an apparatus as shown in Figure 1, the bore 5 through which the liquid is supplied may be 0.375 inch in diameter and the orifice plate may have 4 orifices each 0.06 inch in diameter at a radial distance of 0.156 from the axis. The cylindrical lenath of the tube 6 from A to B may be 1 3/4 inches and its bore 1 inch. The contracting length

is 1 3/8 inch with an outlet or nozzle open in, 0.5 inch in diameter. The conical gauze has 10 meshed to the linear inch, and is 2 inc]ies long, 0.875 incli in diameter of the wider end and 0.25 inch in diameter at the smaller end. It will be seen that in this example the cross-sectional area of the foam-developing chamber is 0.78 square inches and the cross-sectional area of the nozzle is 0.2 square inches, so that the ratio of the one to the other is 3.9:1. The ratio of the square of the length from A to B to the cross-sectional area of the nozzle is 15.6 :1. The length of the contracting part is 0.42 times the overall length A to C. Such a small generator as that just described is very convenient to handle. It may also be fixed to the top of a small foam fire-extinguishing apparatus such as is held in the operator's hand in use. The desirable characteristics of any foam generator are that it should produce foam having the maximum expansion consistent with adequate wetness, should ideally produce a compact jet and should project that jet through the maximum distance. In practice is it always necessary to compromise between these charac- teristics, and it is an advantage of the invention that the compromise can be varied by modifying the obstruction, thus facilitating manafacture of apparatus for different requirements. If the obstruction is a gauze, the important factor is the size of the opening, if any, at the narrower end of the gauze. If no such opening is provided a jet of reduced expansion and reduced range will be produced. By introducing an opening, i.e. making the gauze frusto-conical as shown in Figure 1, the expansion and range will be increased. This increase will continue will further increase in the opening until a point is reached at which the jet ceases to be compact and scatters so much that a substantial proportion of the foam is ineffective. The gauze cone should be as long as practicable to present a maximum area to the flow within the space available and thus to produce the minimum resistance to the flow. It is therefore desirable for the narrow end of the gauze to stop short of the outlet in order to allow the foam to attain streamline flow after passing the gauze. It is preferable, therefore, that the cone should extend from a point near the air inlet to a point near the junction of the foam-developing chamber and the contracing part. The apparatus shown in Figure 2 is line wise designed to work with pre-mixed solutions, but to deliver a larger volume of foam, namely 150 to 200 gallons a minute. It differs from that of Figure 1 in that the obstruction is hot a gauze but a number of rods 12 extending in the general direction of flow but slightly inclined inwardly from

their roots. More over the foam-developing chamber is hot cylindrical throughout. In a typical apparatus as shown in Figure 2, the mean cross-sectional area of the foam-developing chamber is 4.9 square inches and the cross-sectional area of the nozzle is 1.23 square inches, giving a ratio of about 4.1. The length of the foamdeveloping chamber from A to B is 9 inches, so that the ratio of the square of this length to the nozzle area. is 14.7:1. The length of the contracting part is 3 inches, i.e. about 0.41 times the overall length A to C. Tb a apparatus shown in Figure 3 is designed to deliver a still larger volume of foam, namely 500 gallons a minute. Hitherto a standard generator of this capacity has been about 3 or 4 feet long. A generator of similar capacity according to the invention may be only 18" long, and will project a satisfactory jet through about 45 to 50. feet. In the apparatus shown in Figure 3 the foam-stabilising compound is induced by a water stream. The water enters through the open end 13 of the apparatus and passes through a strainer gauze 14 to an orifice 1l5 formed with a sharp corner 19 on the upstream side. Because the water must flow round this corner it contracts slightly in diameter in passing through a chamber 20 immediately downstream of the orifice 15. The foam-stabilising com- pound is drawn into the chamber 20 through a pipe connection 21 terminating in an opening 22. The stream then passes through an orifice 23 and enters the foamdeveloping chamber. The line A is at the downstream face of the orifice 23. It is found important to make the orifice 23 coincide with the minimum diameter of the stream and for this purpose a member 24 in which it is formed is axially adjustable. Since the stream is slightly reduced in diameter on passing through the orifice 23 this orifice is slightly smaller than the orifice 15. In this apparatus the obstruction is constituted by an internal rib 26 the downstream edge of which coincides witb the line B where the foam-developing chamber merges into the contacting part. In this apparatus the ratio of the mean cross-sectional area of the foam-developing chamber to the cross-sectional area of the nozzle is 3.06:1. The ratio of the square of the length of the foam-developing chamber to the cross-sectional area of the nozzle is about 20 and the length of the contracting part is about 0.4 times the overall length A to C. In all the apparatus the total crosssectional area of the jets or jet is, of course, appropriate to the nozzle area having regard to the expansion and to the capacity of the apparatus.

What we chaim is: 1. A foam-generating apparatus of the kind set forth in which the foam tube consists of a cylindrical or substantially cylindrical foam-developing chamber and a contracting part terminating in a nozlze, the foam-developing chamber contains a gauzeor other obstruction to the flow so as to increase the mixing of the liquid and air, adn the ratio of the meancross-sectional area of the foam-developing chamber to the cross-sectional area of the nozzle is between 2.25:1 and 5:1, the ratio of the square of the length of the foam-developing chamber to the cross-sec- tional area of the nozzle is between 11.5:1 and 26:1, and the length of the contracting part is between 1/3 and of the overall length. 2. An apparatus according to Claim 1, designed to work with a pre-mised solu- tion of foam-stabilising compound in water, in which the ratio of the square of the length of the foam-developng chamber to the cross-sectional area of the nozzle is between 11.5:1 and 20:1. 3. An apparatus according to Claim 1 having an orifice through which a water stream flows to form a jet by which foamsabilising compound is induced to form the solution in which the ratio of the square of the length of the foam-developing chamber to the cross-sectional area of the nozzle is between 15.5 :1 and 28:1. 4. An apparatus according to Claim 3 in which the orifice through which the water passe- has a sharp corner upstream. and there is a single slightly smal@@ orifice through which the solution passes. 5. An apparatus according to Claim 4 in which the member in which the smaller orifice is formed is axially adjustable. 6. An apparatus according to any of the preceding claims in which the contracting part is internally convex so as to cause the foam passing through it to accelerate uniformly. 7. An apparatus according to any of the preceding claims in which the obstruction is a conical or frusto-conieal gauze inserted in the foam-developing chamber with its narrower end downstream. and the liquid is so projected into the e chamber that sub- stantially all of it impinges on the inner surface of the gauze. 8. An apparatus according to Claim 7 in which the liquid is delivered into the foam tube as a number of parallel or substantially parallel jets all of such radial distances from the axis of the tube that they must strike the gauze and that none passes direct to the outlet opening (if any) of the gauze. 9. A foam-generating apparatus substantially as described with reference to Figure 1 of the accompanying drawings. 10. A foam-generating apparatus substantially as described with

reference to Figure 2 of the accompanying drawings. 11. A foam-generating apparatus substantially as described with reference to Figure 3 of the accompanying drawings. PROVISIONAL SPECIFICATION Improvements relating to Foam-Generating Apparatus We, THE PYRENE COMPANY LIMITED, a British Company, of Great West Road, Brentford, Middlesex, do hereby declare this invention to be described in the following statement: This invention relates to that kind of foam-generating apparatus in which air is entrained by a flowing solution of a foam-stabilising compound in water and the mixture forms foam in flowing through a tube to a nozzle, which may be formed bv the open end of the tube. Our primary object is to shorten the length of the apparatus and to ensure that it will project the foam as a rope-like jet, such as is often called a solid jet. According to the invention the foam tube contracts in diameter towards the outlet, the contracting part being internally convex, a conical or frusto-conical gauze is inserted in the foam tube with its narrower end downstream, and the liquid is so projected into the foam tube that substantially all of it impinges on the inner surface of the gauze. It is found that the gauze improves the foam and so allows it to become of a suitable quality for projection while travelling through a much shorter tube than usual. Preferably the liquid is delivered into the foam tube as a number of parallel oi substantially parallel jets all of such radial distances from the axis of the tube that they must strike the gauze and that none passes direct to the outlet opening it of the gauze. These jets may most conveniently be produced by the provision of an orificeplate between a pipe through which the liquid stream is delivered and the foam tube, this plate having a set of

* GB785377 (A)

Description: GB785377 (A) ? 1957-10-30

Submarine cable repeater and other housings

Description of GB785377 (A)

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PATENT SPECIFICATION Inventors: BARRIE SHAW BURNETT and 7855377 GEORGE FREDERICK TAYLOR Date of filing Complete Specification: (under Section 3 ( 3) of the Patentr Act, 1949) March 8, 1956. Application Date: March 8, 1955. Application Date: Jan23, 1956 Nc Complete Specification Published: Oct 30, 1957. No 6820/55. o 2232/56. Index at acceptance:-Class 38 ( 1), E( 18: 25). International Classification:-HO 2 f. COMPLETE SPECIFICATION Submarine Cable Repeater and other Housings We, SUBMARINE CABLES LIMITED, a Company organised under the laws of Great Britain, of 22, Old Broad Street, London, E.C 2, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to a submarine cable lo repeater and other housings and more particularly to the arrangement of elements at those parts of the housing at which the cable enters or leaves the interior thereof. In such cable housings it is desirable to is encase the cable entry gland in a mass of water repellent grease, which mass in service conditions is subjected to the external hydrostatic pressure in such a

way to prevent water seeping into the housing. The present invention has for its object to provide a housing of the kind described in which the cable entry arrangement presents an improved seal against the ingress of water at ocean depths. According to the present invention, a submarine cable repeater or other housing comprises a casing having a machined inner bore and a bulkhead held in position within the bore at each end thereof so providing an interior chamber for electrical apparatus between the bulkheads, the cable having access to the interior chamber through said bulkheads, and cable entry glands located outside the interior chamber each gland being formed with a seating face engaging the exterior surface of its associated bulkhead and being enclosed in a chamber filled with water-repellent grease said chamber having an outer closure comprising pressure responsive means subject to pressure outside the housing whereby the pressure at ocean depth transmitted to the water-repellent grease is utilised to improve the seal between the cable entry glands and the bulkheads. 4 S Conveniently, the bulkheads may be formed eachwith a central spigot on its outer side, the bore in the bulkhead through which the cable is led passing through the spigot, and the gland seating against the end face of the spigot 50 In one form the cable entry gland is encased in a cylindrical water-tight chamber, the chamber being closed at one end in water-tight manner by a piston which may be displaced along the cylinder, in response 55 to hydrostatic pressure outside the housing. Preferably the chamber contains an inner coaxial cylindrical element or cap which surrounds the gland, so dividing the chamber into inner and outer portions, there being a 60 vent in the cap for balancing the pressures in the two portions It is thus convenient, where the pressure responsive member is a single piston, for the latter to be annular and slidable in water-tight manner along the 65 outer surface of the inner coaxial cylinder. As an alternative to a single piston there may be provided a plurality of plungers or other pressure responsive elements, each capable of individual displacement in order 70 to balance the pressure within the grease chamber with the external Dressure This has the advantage that should there be jamming of an individual plunger the remainder will remain capable of functioning In this 75 embodiment of the invention the grease chamber which is preferably cylindrical, may be closed at its outer end by an end plate in which is provided a series of circumferentially spaced plunger elements capable of dis 80 placement in apertured recesses formed in the end plate In one such arrangement the plunger elements are of annular cross section and slidable in a water-tight manner along cylindrical recesses formed in the end 85

plate It is also possible in this embodiment to employ a dual portion chamber by means of a cap element enclosing the gland, means being provided for balancing the pressure in the two portions of the chamber 90 It has been found that some of the preferred types of water repellent greases are detrimental to the insulating material used in the cable and in the gland Consequently two types of grease may be used in conjunction, one non-detrimental type being used in the immediate vicinity of the gland and the other as the main sealing mass By means of the preferred arrangement of the cable entry in which a grease chamber in two portions is used it is possible to use two types of water repellent greases, one, which does not affect the insulant in the inner portion in direct contact with the gland and the other in the outer portion, the pressures being equalised by the means referred to above which may advan1 tageously be of a kind such as to prevent the grease in the outer portion of the chamber entering the inner portion. The invention is illustrated in the accompanying drawings as applied to a repeater in 2 o a submarine cable repeater housing in which: Finure 1 is a longitudinal sectional view showing one end of a repeater housing. Figure 2 is a sectional view similar to Figure 1 of a further embodiment showing one end of a repeater housing including the bulkhead and wherein the pressure responsive means consists of a series of piston elements. In the drawings, C indicates the central insulated conductor or core of the submarine cable, H being the repeater housing which is in the form of a cylindrical casing and is usually formed of steel. At each end of the repeater housing H is a counterbore forming a shoulder S to receive a bulkhead B, and between the two bulkheads B is enclosed a central chamber D, within which the repeater apparatus (not 4 shown) is housed The bulkhead B, it will be understood, is machined accurately to fit the counterbore 1 and at the outer end of the casing is a second counterbore 2 to receive an end plate (not shown) which carries the usual armour-anchoring means Extending centrally through the bulkhead B is an axial passage F through which the cable core passes for connection within the chamber D to the repeater apparatus (not shown). Moulded on to the insulation of the cable core C is the cable entry gland indicated generally at 8, this being in accordance with known methods As shown, the gland 8 is formed with a flat seating fsue which abuts against the end of a spigot 11 formed on the bulkhead. In the cable entry gland of this invention, the gland 8 is preferably enclosed within an inner cylinder provided by a cap element 9. For this purpose the bulkhead B is formed with the central spigot 11

screwed as at 10 to receive the cap element 9, the latter having a diameter greater than that of the gland 8, so as to provide an inner and central chamber surrounding the gland, and which, as hereinafter described, is filled with a water-repellent grease The bulkhead B may be formed with an extended circumferential wall 4 together with interior reinforcing ribs 41 so as to provide a water-tight or pressure chamber 70 3, hereinafter termed the 'main' chamber, in which chamber is the main sealing mass of water-repellent grease, the purpose of which is to prevent water seeping through the cable entry and past the gland 8 into the chamber 75 D containing the repeater apparatus. Referring now to Figure 1 the cable core at its entry to the cap element 9 is sealed by an 0-ring 9 ' Vent holes 5 in the wall of the cap element 9 provide connections between 80 the inner chamber 31 and the main chamber 3. In accordance with the invention, the chamber 3 is closed at its open end by means of a pressure responsive element consisting 85 of a single piston 100 This piston 100 is formed as an annular plate and has its inner and outer perimeters of increased depth in an axial direction, as indicated respectively at 102, 103, the outer perimeter 103 making 90 sliding contact with the inner surface of the counterbore 1, while the central bore of the piston, as provided by surface 102, is a sliding fit on the external coaxial cylindrical surface of the cap element 9 95 The counterbore 1 and the external surface of the cap element 9 are machined to very close limits and with the addition of 0-rings the piston 100 seals off in water-tight manner the outer end of the pressure cham 100 ber 3 A collar 109 on the outer end of the cap 9 limits the outer travel of the piston 100. Vents 107 in the piston enable the sealed off part of the main chamber 3 to be filled with water repellent grease, these vents being 105 sealed after the filling operation by screwthreaded plugs. The grease filling the chamber 3 sealed by piston 100 may be a silicone grease or a polyisobutylene but since some of the most suit 110 able materials are harmful to polyethylene, which is commonly used for the gland 8 and the dielectric of the cable core C, a dillerent material, harmless to polyethylene, is then used to fill the inner cylinder 9 The filling 115 may, of course, consist entirely of a material which is not detrimental to the polyethylene. In practice, the inner gland chamber within the cylinder 9 may be packed with a suitable wocater repellent material, e g through a 120 filling hole after it is screwed on to the boss 11, any excess material being exuded through the vents 5 When the piston 100 is in position, the sealed-off outer end of the chamber 3 is filled with a suitable water repellent 125 greas 2 through vents 107 Care is taken

to ensure that all the air is bled out and sufficient grease is introduced to create a pressure within the sealed off chamber 3. Whtnen the repeater is lowered to the sea 130 785,377 29 and they are held in position within their respective cylinders by circlips 30. As will hereinafter be explained, the interior space within the cylindrical chamber 3 divided off by the end plate 14, is filled with 70 a water repellent grease, indicated at 33, and similarly the annular space within the cap element 9 is charged with water repellent grease which may be of the same or of a different type 75 In order to provide a balance between the interior of the cap element 9 and the exterior thereof, balance pressure holes 32, similar to the vents 5 (Figure 1) are provided. Since certain types of water repellent grease 80 are detrimental to the insulating material used in the cable and for the gland 8, it may for this reason be necessary to use one type of grease within the cap element 9 and a second type of grease in the space 30 For this 85 purpose provision is made to prevent direct contact of the two greases, access to the holes 32 being prevented by bellows 35 which are fitted to screwed spigot pieces 36 adapted to screw into the holes 32 90 The end plate 14 is secured in position by a screwed annular retaining ring 37 This retaining ring 37 provides a seating for a flexible cover disc 38 which is formed of rubber or plastic and secured around its perimeter 95 by a second ring 39 The cover disc 38 has a central opening 40 which is seated against the end of the spigot 17 and secured in position in a water-tight manner by a clamping ring 41 which is shouldered to engage the 100 cover disc The clamping ring may be held in place by set screws 42 is a gasket, of resilient material. During assembly of the cable entry gland, the space around the gland 8 is filled witlh a 105 water repellent grease The bellows 35 are filled with the same grease and fitted in position The outer and main cylindrical chamber 3 may then be filled with the main mass of grease 33, following which the end plate 110 14 is secured in position but without the plungers 26 in it The cylinders 24 are then filled with grease and the plungers 26 are secured in position without the plugs 28 in them and with the central closing plug 19 115 loosely fitted Grease is next injected into each of the cylinders 24 behind the plungers through one of the plunger bleed holes 27 until it exudes past the gasket 4-2, and the remaining bleed holes, thus ensuring that no 120 air is trapped among the grease The piston plugs 28 are then fitted in position and the closing plug 19 tightened. The flexible protective cover 38 is next secured in postiion with water repellent grease 125 between it and the plungers 26 to prevent matter from, say the sea bed, entering the plungers 26 and causing

them to jam Once the repeater is in position on the sea bed and the plungers 26 have taken a more or less 130 bed, sea water, which is free to pass through the end plate, enters the outer end of the chamber 3 where it exerts pressure on the outer face of piston 100 Under this pressure the piston moves down the chamber 3 until the pressures on its opposite faces are balanced As a result the external hydrostatic pressure is transmitted through the piston 100 to the grease in chamber 3 and through vents 5 to the grease in the inner cylinder 9, thus causing the seating face on the gland to seal more effectively against the end of the spigot. In this way there is provided in each end of the repeater casing a barrier chamber containing water repellent grease at the same pressure as the surrounding sea water, which prevents water coming into contact with the gland or with the seal between the bulkhead and the casing, the barrier chamber being closed at one end by a pressure responsive means consisting of the piston element 100 which operates to balance pressure within the chamber with the pressure outside. Referring now to Figure 2 there is shown a preferred form of the invention where in place of a single annular piston 100 there are provided a number of circumferentially spaced plunger elements. As in the construction shown in Figure 1 the cable entry gland is enclosed within a cap element 9, the interior of which is similarly filled with water-repellent grease In this embodiment of the invention the cap element 9 is formed with an axial extension 12, in which is an opening 12 ' for the passage of the core C, an O-ring 13 being provided at this point to form a seal The main chamber 3, provided by the counterbore 2, is closed at its open end by an end plate 14, this plate being formed with a peripheral flange which is shouldered and accurately machined to fit the counterbore 1 It is sealed to the casing 1 by an "O" ring 16. The end plate 14 is of conical formation and has a central hollow spigot 17 providing an opening for the extension 12 of the cap element The opening is screw-threaded as at 18 to receive a closing plug 19 On the inside face of the end plate 14 is an annular seating 19 ' by which it is located in an axial direction against the end of the cap element 9. In the end plate 14 are a series of circumferentially spaced, axially extending, recesses constructed in the form of cylinders 24, these cylinders benig provided at their inner ends with openings 25 giving access to the chamber 3 Slidably mounted within each of the cylinders 24 is a pressure responsive element consisting of a plunger 26, these plungers 26 having central bleed holes 27 which are sealed with headed pins or plugs 28 Likewise the plungers 26 are sealed in a watertight manner to the cylinders 24 by " O " rings 785,377 4 785 377 permanent

position in the cylinders 24 the flexible protective cover 38 may be dispensible and may through corrosive action, etc. from the sea gradually disintegrate. The displacement of the plungers 26 should be greater than their displacement due to water pressure so that if one of the cylinders ceases to function the other cylinders may balance the pressure. The piston plugs 28 may be secured in position in such a manner to act as pressure safety valves should the inner pressure exceed the outer oressure when the repeater is being raised from the sea bed. It will be appreciated that the water repellent grease also serves as a means of sealing the counterbore I between the bulkhead and the casing, which may be further sealed by brazing or other known ways. in certain circumstances the flexible protective cover 38 used in the arrangement shown in Figure 2 can be applied to the cable entry gland of Figure 1 having a single piston.

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