DH Instruments PPC2 AF - Supply Pressure Relief Valve Removal and Replacement; Reloading Embedded Software into Flash Memory; Overhaul

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PPC2 AF OPERATION AND MAINTENANCE MANUAL

5.1.2.8 SUPPLY PRESSURE RELIEF VALVE REMOVAL AND

REPLACEMENT

See Figures 1, 2, 3 and 7.

Remove all power and pressure prior to any disassembly.

1. Remove top and bottom covers (fig. 7)

2. Disconnect fittings (102491, 101985 and bulk head nut).

3. Remove pressure relief valve from assembly.

3.1. Disconnect fittings on valve to use on new valve if part is to be

replaced.

4. Install new or repaired part.

5. Reassemble PPC2 AF.

Leak check unit prior to use.

5.1.2.9 RELOADING EMBEDDED SOFTWARE INTO FLASH

MEMORY

1. The PPC2 AF has flash memory, which means that when an upgrade is

required or for some reason the embedded software is corrupted it can be

reloaded with the help of a PC.

2. If new versions of software are to come DH Instruments will send the

FLASH instructions along with the new software.

3. If the embedded software is suspect of a problem, write down all symptoms

and call DH Instruments technical service. If indeed a new FLASH is

required instructions and all required software will be provided.

5.1.3 OVERHAUL

If calibration of the reference pressure transducers is included as part of the overhaul

procedure, the calibration procedure must be performed last as other overhaul procedures

may affect reference transducer calibration.

Any or all of the following items may be included as part of a system maintenance overhaul:

1. Verify operation of supply pressure relief valve.

2. Disassemble pneumatic module filters and clean filter elements. Replace if necessary.

3. Clean front panel.

4. Clean threads of rear panel fittings. Check for damage and replace if necessary.

5. Check that rear panel cooling fan operates when PPC2 AF is on.

6. Check that internal screws, bolts and nuts are tight.

7. Check that the gas flow through exhaust port when not controlling pressure is between

500 sccm (test port at atm) and 1.5 slm.

8. Verify that internal barometer reads atmospheric pressure within +/- 0.15 psi of reference

transducer range L1, L2 and/or L3.

9. Perform calibration of reference pressure transducers if necessary.

10. Perform system leak and operational check.