Peter Barnes, LLNL
Version 0.1
October 19, 2001

E907 TPC Purge Procedure

NOTE: This procedure MUST be completed before AND after flowing P10.

The E907 TPC uses P10, a flammable gas. This purge procedure minimizes the amount of oxygen in the system.

The goal is to purge 95% of the atmospheric oxygen by assuring a minimum of three volume changes with inert gas, in our case nitrogen. The TPC chamber and gas system volume is 2.06 m3 total. The purge flow rate is 6 liters/min. The volume change time is 344 min or 5.73 hours; three volume changes take 17.2 hours. This procedure calls for a minimum of 18 hours purge (a total of 6.48 m3 of gas. A standard supply cylinder contains 6.36 m3 (227 scf) of gas, so this procedure consumes slightly more than one cylinder of nitrogen.

Purge Procedure

This procedure assumes that both the main nitrogen supply and the reserve supply will be used, and sets the pressure on the nitrogen (PRV-03 and PRV-04) and system (PRV-05) pressure regulators.

Name

Date

Time

 

 

 

÷ 

Step

Action

 

Prepare the System

 

1.

Close these valves: MV-03, MV-06, MV-15, MV-16, PRV-03, PRV-04, and PRV-05.

 

2.

Open MV-017 and record the reading on PI-03:

PI-03 Magnehelic (in H2O)

 

 

3.

Verify that the bubblers, BUB-01 and BUB-02, contain oil, and that the oil level is not more than 1" above the bottom of the bubbler tube.

 

4.

Set the gas selector valve, MV-14, to the nitrogen supply, not the P10 supply.

 

Set Up the Nitrogen Reserve Manifold

 

5.

If the nitrogen reserve manifold has been exposed to air, perform the TPC Bottle Change Procedure to purge the manifold. (This step is necessary if this procedure is being used after flowing P10.)

 

6.

Set the nitrogen reserve manifold outlet, MV-12, to feed to the system, not the vent.

 

7.

Verify that the nitrogen reserve cylinder valves, MV-10 and MV-11, are open.

 

8.

Open the nitrogen reserve manifold regulator, PRV-04, until its outlet gage reads 10 psi.

 

9.

Open the nitrogen supply valve, MV-13, and verify that the system regulator inlet pressure, PI-01, reads 10 psi.

 

10.

Close the nitrogen supply valve, MV-13.

 

Set Up the Nitrogen Main Manifold

 

11.

If the nitrogen main manifold has been exposed to air, perform the TPC Bottle Change Procedure to purge the manifold. (This step is necessary if this procedure is being used after flowing P10.)

 

12.

Set the nitrogen main manifold outlet, MV-9, to feed the system, not the vent.

 

13.

Verify that the nitrogen main cylinder valves, MV-07 and MV-08, are open.

 

14.

Open the nitrogen main manifold regulator, PRV-03, until its outlet gage reads 15 psi.

 

15.

Open the nitrogen supply valve, MV-13, and verify that the system regulator inlet pressure, PI-01, reads 15 psi.

 

Set Up the System Regulator

 

16.

Open the system regulator, PRV-05, until its outlet pressure, PI-02, reads 1 psi.

 

Initiate Nitrogen Purge Flow

 

17.

Slowly open the low flow valve, MV-15, watching the chamber pressure on PI-03.

Do not let the chamber pressure exceed 0.8 in H2O on PI-03.

 

18.

Set the low flow meter, FI-01, to x.

Do not let the chamber pressure exceed 0.8 in H2O on PI-03.

 

19.

Record the full purge rate start time:

Purge Flow Start Time

 

Estimate Purge Complete
= Start Time + 18 h

 

 

20.

Record purge complete time:

Purge Complete Time