1

LST Gas System

R. Messner

May 2004

Readiness Review

2

Will cover a few of the items below

• Gas Mix – the issue of what gas mixtures will be allowed in the LST system has been resolved

– FHA: O’Neill, Budnick– HEEC review

• Gas Mixing System– In leak test– Want to test output flows ASAP– Integrate with the GIB

• Gas Interrupt Box (GIB)– Finished with checkout– Had found problems with firmware; fixed

• IR-2 Distribution Panels– Flow restrictor in hand, checked out

• Gas Supply Manifolds– Next to be assembled

• Gas Shack Safety System Expansion underway

• Electrical

• External Monitor System

3

Gas Mix Instead of getting a specific mix approved,

we want approval for a region of mixes

0 20 40 60 80 100

0

20

40

60

80

100

Per Cent Argon

%CO2=100-%Ar-%Isobutane

Not 'Physical'

Representation of a three component gas

Possible Mixes

Bureau of Mines Tci

CERN Tci

4

Gas Mix The operating region takes into account the stability we have seen in the RPC system

0 2 4 6 8 10

7.5

8

8.5

9

9.5

10

Compare_errors_vs_flammable_region_II

Per Cent Argon (proposed limit, 9.7% isobutane at 0% argon)

Runnable Region (9.41 % isobutane at 0% argon)

Runnable Region +- 1.0% drift

Example Point (8.65% isobutane, 3% argon)

Per Cent Argon

All Operational Settings Are To Be Below the Blue Line

%CO2=100-%Ar-%Isobutane

5

G as In te rru p t B ox

M o n ito rs gas flow s;w ill sh u t o ff in pu ts ifflo w s or ra tio s areno t corre c t

(h o m e m a d e )

F low C o ntro l B o x

O n e m a ste r flo w ;s la ve s se t b y ara tio to ac tu a l f lo wo f m a ste r

M a ss F lo w C o ntro lle rs

C O 2 C O 2

A r A r

Iso Iso

M a ss F lo w M e ters

Pre

ssu

reS

ens

ors

M ass F lo w M ete r R e a d in gs

Ve n t

Sta tu s

S a m p leP o rt

A fourth mass flow meter can provide a tie-breaking vote in case of MFM/MFC disagreementCan also pick up small drifts in mixed gas flows

Shut-off solenoids will close if the gas mix drifts out of the allowed region

Mixing System Functionality

6

Gas Rack - in leak test

7

Gas Rack

8

Gas Interrupt Box Functionality

Reading InFrom Flowmeters

0-5 Volts

Reading Out

SolenoidPower

Trip?

Reading In Range?

To Monitor

To MonitorTo Monitor

ToSolenoids

ShutOffPower

S

S im p so n 2

%

S

S im pso n 2

%

Iso

CO2

S

S im p so n 2

%

Argon

Reading In Range?

Reading In Range?

S

S im p so n 2

%

Mix

9

GIB in checkout

10

Overview of the IR-2 Distribution

Layer Distribution Manifold with Resistors

Sextant Distribution Manifoldwith safety bubblers and rotameters

Left Side Modules

Right Side Modules

PSI “ H2O

Output Collection Manifold with Bubblers

Le ft H a lf

R igh t H a lf

Le ft H a lf

R igh t H a lf

11

Silica tubing flow resistor

12

Check of silica tubing flow resistance

0

1

2

3

4

5

0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04

Delta_P_thru_one_inch_of_tube

Delta P (inches H20) for 5.22 liters per hour thru one inch of tubeMeasurement y = 2.0575e-07 * x̂ (-3.9842) R= 1

Inner Diameter (inch)

Measured at 50 cc/min: Delta P = 1.8-2.0 inches H2O for a 1.875 inch long piece of 0.53 mm ID silicon tubing

13

Gas Shack Layout

22 feet

RPC

DCH

inertgas

DCHgas

DCHgas

elec

Cabinet

Term

inal

15.5Feet

12 Feet19 Feet

10 FeetCovered

North

CO2

Air

He

MH-6

ElectricalPanel

Fan

3.88 in

VMEcrate

Light

Light

DCH and RPC Manifold Panels

N2

Argon

Construct a new isobutane supply rack and manifold;Will have two isobutane shutoff valves, orifice

Two new inert gas supplies;Each will have a shutoff valve, orifice, overpressure releases

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Summary

• The loose ends involved in determining a permissible gas mix have been resolved

• Very close to having a functional mixing system with its monitor system to ensure a non-flammable and a runnable mix– Use air or nitrogen, check the self consistency

and stability of system

• It is important to keep moving ahead; sufficient and timely technical support is critical– Want the gas rack in the gas shack before the end

of May– Delayed a bit because we want to get the manifolds

done first; then we can do more things in parallel

• Expansion of Gas Shack safety system in progress

• EPICs monitor system will be the next item to attack

15

Spare Slides

16

Looked at the recent performance of the RPC system

Snapshots taken a week apart, a half day at a time

This is a measure of the stability of the gas mixture

+- 0.0005 out of 0.045

Or ~ 1.0 % of the reading

0.044

0.0445

0.045

0.0455

0.046

0 2000 4000 6000 8000 10000 12000

gasreadings_output_oct_dec_2003_cleaned

Fraction of Isobutane

Index

11/20 11/27 12/04 12/11 12/18

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Recent performance of the RPC system

0

500

1000

1500

2000

Percentage Isobutane

Range

-1 % of nominal+1 % of nominal

Isobutane Fraction in Gas Mixture