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-overflow tanks-

Present design status

T. Wise, for Wisconsin Group

AD Preliminary Design Review, July 30, 2007, IHEP

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Overflow tanks• Overflow tanks are required to absorb volume changes

and to maintain constant pressure on the PMT’s.• Absorb thermal expansion• Absorb mechanical deformation• Nested design eliminates trapped

volumes and bubbles• Three isolated liquid surfaces

equalized by common barometric pressure

• Reduces GDLS target

LS and GDLS

MO

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Scintillator Overflow volume requirement 150-200Liter

4 meter dia. sphere with 4mm slice has 25 liter volume

4mm

Thermal: estimate about 20 liter/degree C for scintillator

If acrylic bottom follows the curvature of the ss tank we expect a maximum of 3mm deflection from immersion in water tank.

Mechanical distortion of acrylic bottom: estimate < 25 liter.

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Open issue: Temperatures in Hall 5, Tunnel, and water pool need to be defined.

The present overflow design can accommodate a 5 degree C difference among the three environments

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Nested LS & GDLS Overflow TanksSeparate & Larger MO Tank

Gd LS 1.3 meter dia.

200 liter capacity

LS 1.8 meter dia.

200 liter capacity

Calibration domes

MO 320 liter capacity

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Overflow Tanks (cont.)

Gd LS Level

LS Level

5meter Lid

Overflow Lid ribs

Calibration box mounting flange

Level meter “houses”

Qty 5: 2US, 2 China, 1 emergency shut off30 cm height

limit line

LS

5 meter Lid ribs

Atmospheric pressure N2

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Overflow Level Measurement

• Accuracy of ±1mm out of 200mm maximum• Long term contact with LS & GDLS• Compact assemblyWisconsin is testing a pressure gage to determine liquid column height.

170 mm

Sensitivity of ±1mm is more than required but it will help us see trends before they become problems, i.e. evaporation of GDLS or some types of leaks

Siemens P300 pressure gage

We need the “gage” version not the “absolute” version

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Lifting Fixture ClearanceIHEP is designing a lifting fixture to aid in lifting the AD. The fixture should be designed to clear any attachments up to 30 cm above the lid.

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Three Penetrations into LS & GDLS Volumes

One central, two outer

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We have concern that the fasteners may be difficult to access and complete. A practice assembly exercise with prototype AV’s is planned.

Teflon bellows will be a custom manufacture.

Central overflow tank connection

Outer GDLS connection

Teflon Bellows Connections between Calibration Domes and Acrylic Vessels

Baseline configurations shown here.

N2

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Bellows attach directly to 3m and 4m lids. No acrylic tubing is necessary

Central overflow tank connection

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Flanges with threaded holes bonded to acrylic top plates

Lower attachment designs

O-ring seal with split ring clamp plate

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LS

LS G D

L S

Upper attachment designs

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Special details related to the outer GDLS calibration penetration

Support spool volume is not used for liquids. Filled with dry N2

GDLS is sealed by gate valve at same height as the other two gate valves.

Assembly sequence is workable if we are careful. See next slides

N2

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1) Attach inner bellows to top of 3 meter acrylic

2) Attach outer bellows to lid of 4 meter acrylic

3) Lower 4 meter lid while threading inner bellows through hole

4) Connect top of bellows to intermediate bellows top plate (this is the difficult step!)

5) Lower SS lid and fasten intermediate top plate to custom acrylic spool

6) Attach valve

7) Fix LS vent fitting

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Step 4: make top bellows assemblyPotential gas pocket

CL

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Step 7: Fasten LS vent fitting

LS

GDLSMO

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Our sample

1mm wall

49mm ID, 60mm OD

Corrugation length 375mm

Spring constant 54 Nt/cm

Teflon Bellows Information

Flared cuffs are available

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• Open issues: Outer GDLS penetrations may have interference with SS tank rib design

• Need definite limits to

Outer GDLS calibration dome

These two features might not be compatible

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Overflow R&D topics• Build acrylic lined nested overflow prototype

• Stability of P300 level sensors, minimize exposure to SS

• Teflon bellows O-ring seals with flared cuffs

• Realistic penetration assembly test with mock-up geometry

• Make connection of prototype calibration system to prototype overflow tanks

• All acrylic fasteners and split flanges

• Overflow materials in contact with scintillator• SS (possibly vapor only)• Teflon• Acrylic• Viton• Gate valve (vapor only)• …