Operation Teledyne API M701H High Performance Zero Air Generator
5-8 06712B (DCN5875)
5.2.11 Pressure Gauge
The front panel-mounted pressure gauge shows approximately the regulated air
pressure available to a calibrator. The gauge will usually indicate 30 psig. If the flow is
very low, as in a standby condition, the gauge may read slightly higher. It will move to
the correct reading when the air flow is increased. When the demand on air increases
dramatically, the pressure may drop below 30 psig. At maximum air flow, 30 SLPM, you
may notice that the pressure drops to 29 psig for a standard operation.
5.2.12 Hydrocarbon Scrubber
The High Purity Hydrocarbon Scrubber includes the CO Scrubber.
The optional Hydrocarbon scrubber catalytically converts hydrocarbons to carbon
dioxide and water. The scrubber consists of a cylindrical cartridge which contains a
preheat chamber and the pelletized precious-metal catalyst. The canister is heated by a
band heater with an integral type-K thermocouple and is housed in a stainless steel
casing with appropriate thermal insulation. The cartridge temperature is controlled by
the instruments printed circuit assembly. The controller reads the thermocouple voltage,
compensates for cold-junction temperature and modulates the heater to maintain a
constant cartridge temperature.
(Refer to Appendix B, P/N )
The operating temperature of the cartridge is 300ºC. The temperature can be verified by
measuring the thermocouple voltage at the two terminal blocks of J12 (labeled “Thermal
Couple” in Figure 5-3). At 300ºC, the thermocouple voltage is 11.2 mV in an ambient
temperature of 25ºC (11.4 mV at 20º and 11.0 mV at 30º). While the controller
compensates for cold-junction temperature in controlling the heater, the thermocouple
voltage at the terminal block is not compensated, so allowance must be made for
ambient temperature when converting the voltage to cartridge temperature.
CAUTION
THE AIR LEAVING THE SCRUBBER IS AT 300C (575F).
THE AIR IS COOLED IN THE COPPER COIL AND CASINGEXIT
TUBING BEFORE IT ENTERS THE NO SCRUBBER.
THIS COPPER COIL AND THE CASING CAN BE VERY HOT.
The catalyst is proprietary. It theoretically should never need changing. However, it may
become contaminated or poisoned over time so we recommend that the scrubber be
replaced once per year or sooner.