377 Series Trip Valves

8/11/2019 377 Series Trip Valves

1/8

www.Fisher.com

377 Series Trip Valves

The 377 Series pressure-sensing trip valves (seefigures 1 and 2) are for control applications where aspecific valve/actuator action is required whensupply pressure falls below a specific point. Whensupply pressure falls below the trip point (see figure3), the trip valve causes the actuator to fail up, lockin the last position, or fail down. When the supplypressure rises above the trip point, the 377 Seriestrip valve automatically resets, allowing the systemto return to normal operation. The trip valve can betop-mounted on a manifold, yoke-mounted, orbracket-mounted to match the applicationrequirements. The 377 Series trip valves can beused with 480, 585C, 1061, 1066, 1069, and G

Series piston actuators.

Features

Cost EffectiveSingle trip valve constructionreduces costs and spare part requirements of thosesystems using three separate switching valves toperform the failure functions. A single trip valvegreatly simplifies piping requirements.

Ease of Mode ConversionConversion to anyof the fail modes requires only minor hookupchanges.

Adjustable Trip ValveThe trip point isadjustable for specific supply pressure requirements.

Reliable OperationThe trip valve designincludes large diaphragm areas and few movingparts for efficient performance, minimummaintenance, and long service life.

W4292-1/IL

Figure 1. 377 Series Trip Valve

W8435-1

Figure 2. Type 377 Trip Valve Mounted on Size 130 Type585C Actuator

Product Bulletin62.3:377October 2002 377 Series Trip Valves


2/8

377 Series Trip ValvesProduct Bulletin

62.3:377October 2002

2

Specifications

Available Configurations

When supply pressure falls below the trip point,Type 377D Trip Valve:Fails actuator pistondown. Includes check valve and volume tankType 377L Trip Valve:Locks actuator piston inthe last positionType 377U Trip Valve:Fails actuator piston up.Includes check valve and volume tank.

All 377 Series Trip Valves can be converted toany of the above fail modes with minor hookupchanges

Allowable Supply Pressure for Trip Valve

Maximum:10.3 bar (150 psig)

Minimum:3.8 bar (55 psig)

Outlet Pressure

Normal Operation:Pressure from control deviceFail-Up or Fail-Down Mode:Maximum volumetank pressureLock-In-Last-Position:Respective cylinderpressure

Trip Point(1)

Adjustable from a minimum of 2.8 bar (40 psig) toa maximum of 72 percent of supply pressure; seefigure 3.Reset:12.5 to 33 percent above adjusted trippoint

Flow Coefficients (Cv)(2)

Depends on flow path (shown in figure 4) asfollowsPort A to Port B: 0.47Port B to Port C: 0.56Port D to Port E: 0.48Port E to Port F: 0.64

Body Connections

1/4-inch NPT female

Temperature Capabilities

Nitrile Diaphragms and O-Rings:40 to 82!C(40 to 180!F)Fluoroelastomer Diaphragms and O-Rings:

18 to 104!C (0 to 220!F)

Volume Tank Maximum Internal WorkingPressure

Standard:14.5 bar (240 psig) for Type 377D or377UASME Approved:9.3 bar (135 psig) for Type377D or 377U

Volume Tank Sizing

See sizing section

Mounting

Top-Mounted:Manifold-mounted between thepositioner and 480 Series actuator (manifoldscannot be supplied with 585C, 1061, 1066, and1069 Series piston actuators)Side-Mounted:Yoke mounted or bracketmounted

Approximate Weight

Trip Valve:2.0 kg (4.5 pounds)Mounting Manifold:0.5 kg (1.2 pounds)Volume Tank:Varies between 5.4 and 21 kg (12and 47 pounds) depending on size

Construction Materials

Body, Spring Case, and ManifoldAluminumCover25% mineral-filled thermoplasticpolyesterO-Ringsnitrile or fluoroelastomerDiaphragmsnitrile or fluoroelastomerInterior partsbrass, aluminum, steel, andstainless steel

1. If the trip point is not specified, the trip point is factory-set at 72 percent of supply pressure or 2.8 bar (40 psig), whichever is higher.

2. Values represent nominal Cvmeasures for each port pair using a trip valve/actuator combination.


3/8


Product Bulletin62.3:377October 2002

3

10.34 5 6 7 8 9 10

110

100

90

80

70

60

50

40

7.6

7

6

5

4

3

1501401301201101009080706055

NOTE:

TRIP POINT MAY BE SET TO ANY VALUE BETWEEN

2.8 BAR (40 PSIG) AND THE MAXIMUM TRIP POINT LINE.

RESET OCCURS AT 12.5 TO 33 PERCENT

ABOVE ADJUSTED TRIP POINT.

TRIPPOINT,PSIG

TRIPPOINT,BAR

SUPPLY PRESSURE, BAR

SUPPLY PRESSURE, PSIG

A2779-2/IL

MAXIMUM TRIP POINTSETTING TO ENSURERESET

1

1

2

2

Figure 3. Maximum Trip Point Settings

UPPERDIAPHRAGM

EXHAUSTPORT

RESTRICTION

PORT A

PORT B

PORT D

PORT E

PLUGASSEMBLIES

PORT F PORT C

VALVEPLUG SPRING

SUPPLYCONNECTION

LOWERDIAPHRAGM

W4303-1/IL

Figure 4. Simplified Sectional View of Trip Valve

Principle of Operation

Type 377D Trip Valve

In normal operation, supply pressure loads the upperdiaphragm (see figure 4) of the unit. The valve plugspring keeps the exhaust port closed. Supplypressure also loads the lower diaphragm through therestriction, causing the plug assemblies to movedown and isolate ports C and F while connectingport A to B and port D to E. Normal actuator controlpressure flows from the control device to the top ofthe cylinder through ports A and B and to the bottomof the cylinder through ports D and E. A volume tankis charged to maximum supply pressure through acheck valve in order to retain maximum supplypressure in the volume tank if supply pressure drops.

When supply pressure falls below the trip pointpressure in the fail-down mode (see figure 5), theexhaust port opens, venting the supply pressure thatis loading the lower diaphragm. This causes theupper ports of the plug assemblies to close and shutoff normal pressure flow from the control device tothe actuator.

Volume tank pressure then flows through ports Cand B to the top of the actuator cylinder, whilepressure in the bottom of the actuator cylinder isvented through ports E and F. The pressureimbalance created forces the actuator piston down.

When supply pressure is restored, it loads the upper

and lower diaphragms, causing the trip valve toreset. The exhaust port closes. The upper ports ofthe plug assemblies open, and the lower ports close.Normal actuator control pressure flow from thecontrol device is restored through ports A and B andports D and E. The check valve opens and rechargesthe volume tank to the maximum supply pressure.

Type 377L Trip Valve

When supply pressure falls below the trip point in thelock-in-last-position mode (see figure 6), the exhaustport opens, venting supply pressure from the lowerdiaphragm. This causes the upper ports of the plugassemblies to close and the lower ports to open.Since ports C and F are plugged, no pressurechange occurs on either side of the actuator piston,and the piston is pressure-locked in position uponloss of supply pressure. No volume tank isnecessary in this mode. When supply pressure isrestored, the plug assemblies move back into thenormal operating position, and supply pressure flowsfrom the control device through ports A and B to theactuator.


4/8


62.3:377October 2002

4

35A6996-CA2283-4/IL

Figure 5. Type 377D Trip Valve Shown Tripped

35A6998-CA2285-4/IL

Figure 6. Type 377L Trip Valve Shown Tripped


5/8



5

SPRING

VALVE PLUG

UPPERDIAPHRAGM

EXHAUSTPORT

SUPPLYPRESSURE

LOWERDIAPHRAGM

PORT D

PORT E

LOWERPORTS

PORT F

PORT C

PLUG ASSEMBLIES

UPPER PORTS

PORT B

PORT A

VENT

MAINSPRING

ACTUATOR

CONTROLDEVICE

CHECKVALVE

VOLUMETANK

SUPPLY PRESSURE

CONTROL PRESSURE TO TOP OFCYLINDER (BLOCKED)

CONTROL PRESSURE TO BOTTOMOF CYLINDER (BLOCKED)

PRESSURE FROM TOP OF CYLINDER(VENTING)

PRESSURE TO BOTTOM OF CYLINDER(FROM VOLUME TANK)

LOWER DIAPHRAGM LOADING PRESSURE(BEING VENTED)

35A6997C

A22845 / IL

Figure 7. Type 377U Trip Valve Shown Tripped

Type 377U Trip Valve

The fail-up mode of operation (figure 7) is similar tothe fail-down mode of operation except thatconnections to port C and F are reversed. When

supply pressure falls below the trip point, the top ofthe actuator cylinder vents, and volume tankpressure loads the bottom of the actuator cylinder.The pressure imbalance created forces the actuatorpiston up.


6/8


62.3:377October 2002

6

A2281-1 / IL

Figure 8. Volume Tank Sizing Graph

Volume Tank Sizing

Note: State and local regulations may require theuse of ASME-approved volume tanks. Determinerequirements and applicable regulations forproper volume tank selection.

Seven different tanks of varying capacities areavailable. The volume tank must be selected so thatits pressure at any time is greater than the minimumpercentage of maximum supply pressure required tostroke the actuator (see figure 8).

1. Size the volume tank as indicated below:

For Actuators onSliding Stem Valves,

Determine:

For Actuators onRotary-Shaft Valves,

Determine:

Y= F/AP x 100 Y= Pr/P x 100

Where:

Y = Minimum failure positioning percentageF = Actuator thrust required in normal operation toposition the valve at the desired limit of travel

A = Effective piston area (from the appropriateactuator bulletin)P = Maximum supply pressure availablePr=Highest pressure required by the actuator tostroke the valve (from the appropriate actuator sizingtechnique)

2. With the minimum failure positioning percentageobtained in step 1, enter the value on the abscissa ofthe graph in figure 8. Locate the corresponding pointon the curve, and read across to find the volume ratio,R.

3. Determine:

VT= (XA)/R

Where:X = Maximum actuator travel from the appropriateactuator bulletin. For rotary actuators, substitute totaldisplacement (XA). Actuator displacement can befound in the product bulletin, or contact your Fishersales office.VT= Minimum volume tank size requiredR = Volume ratio from step 2


7/8



7

Table 1. Standard Volume Tank Dimensions

Tank Volume J L

Liters Inch3 mm Inches mm Inches

11.8

21.633.442.965.6

721

1315203626154001

309

310309309309

12.16

12.1912.1612.1612.16

318

4516077371095

12.5

17.7523.8829.0043.12

131.1 8002Requires two 65.6 liter (4001 inch3) volume

tanks

Table 2. ASME-Approved Volume Tank Dimensions

Tank Volume J L

Liters Inch3 mm Inches mm Inches

8.5

24.930.042.868.871.6

518

15201831260941994371

208

305254305360305

8.19

12.0010.0012.0014.1912.00

337

427684681792

1087

13.25

16.8126.9426.8131.1942.81

143.2 8742Requires two 71.6 liter (4371 inch3) volume

tanks

Canadian Registered

114227303454

6930138601848027720

406508610610

16202424

1034128612951932

40.6950.6351.0076.06

908 55440Requires two 454 liter (27720 inch3) volume

tanks

AF4605-K19A7995-A

A2778-4 / IL

57(2.25)CAPREMOVALCLEARANCE

1/4-18 NPTVENT CONNECTION

(mm)INCH

76(3.00)

90(3.56)

54(2.12)

141(5.56)

46(1.81)

100(3.94)

154(6.06)

PORT D

PORT E

PORT F

PORT C

LL

JJ

1/4-18 NPTSUPPLY CONNECTION

1 1

NOTEREFER TO TABLES 1 AND 2 FOR J AND L DIMENSIONS1

Figure 9. Dimensions of Trip Valve with Manifold (Also See Tables 1 and 2)

InstallationThe 377 Series trip valve may be mounted in anyposition without affecting normal operation.

Dimensions are shown in figure 9 and tables 1 and2.


8/8


62.3:377October 2002

8

Ordering Information

Note: Fisher does not assume responsibility forthe selection, use, or maintenance of anyproduct. Responsibility for proper selection, use,

and maintenance of any Fisher product remainssolely with the purchaser and end user.

When ordering specify:

Application1. Available supply pressure2. Actuator type number and size3. Input signal range4. Operating ambient temperature5. Trip point (If the trip point is not specified, the unitis factory-set to trip at 72 percent of supply pressureor 2.8 bar (40 psig), whichever is higher.)6. Volume tank size

Trip ValveRefer to the specifications. Review the informationunder each specification and in the referencedfigures. Specify the desired choice wherever there isa selection to be made. Be sure to specify the typenumber as described in the Available Configurationsspecification.

Refer to table 3 for guidelines on specifying thecorrect trip valve.

Table 3.Guidelines for Specifying 377 Series Trip Valve

Actuator Type Fail ModeValve

Action(1)Trip Valve

PDTC 377U

Sliding-

Fail OpenPDTO 377D

Stem

PDTC 377DFail Closed

PDTO 377U

Rotary--

FullyClockwise

377CW

Type 1035,Series G

FullyCounter-clock

wise

Clockwise toClose

377CCW

Rotary--

FullyClockwise

- - - 377CW

Type 1069 Fully Counter-clockwise

- - - 377CCW

1. PDTCPush Down to Close; PDTOPush Down to Open

FisherMarshalltown, Iowa 50158 USACernay 68700 FranceSao Paulo 05424 BrazilSingapore 128461

The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy,they are not to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their useor applicability. We reserve the right to modify or improve the designs or specifications of such products at any time without notice.

Fisher does not assume responsibility for the selection, use or maintenance of any product. Responsibility for proper selection, use andmaintenance of any Fisher product remains solely with the purchaser and end-user.

Fisher Controls International, Inc. 1985, 2002; All Rights Reserved Printed in USA

Fisher is a mark owned by Fisher Controls International, Inc., a business of Emerson Process Management. The Emerson logo is a trade-mark and service mark of Emerson Electric Co. All other marks are the property of their respective owners.

Emerson Process Management

www.Fisher.com

377 Series Trip Valves

Documents

Transcript of 377 Series Trip Valves