Changing The Thermistors - Emerson Rosemount Model 500 Retrofit Instructions

Installation
September 2019
10. With valves 1-4 closed, open both cylinder valves and regulate both carriers to
11. Open V-2 and V-3 simultaneously; then turn both cylinder valves off and let the
12. Repeat
13. Leak check all the fittings carefully.
14. Let the GC run overnight before calibrating.
2.5

Changing the thermistors

Use this procedure to change the helium thermistors to hydrogen comparable
thermistors.
WARNING
EXPLOSION HAZARD
Failure to observe this warning may cause death or serious injury to personnel.
Hydrogen is potentially explosive. Use extreme caution when using hydrogen as the
gas chromatograph's carrier gas.
To prevent ignition of hazardous atmospheres, disconnect from supply circuit before
opening the enclosure. Keep tightly closed when circuits are alive. For division
installations using a conduit, a sealing device must be connected within 18 in. (460
mm).
Procedure
1. Turn off power to the gas chromatograph.
14
approximately 10 psig.
carrier gases bleed through the line to the GC until all gauges read 0 psig.
Step 8 and Step 9 twice to purge the line to the GC.
Retrofit Instructions
SK-07781
Emerson.com/Rosemount