Teledyne 701 Manuel D’Utilisation
Teledyne API Model M701 Zero Air Generator
OPERATION
01671H (DCN6051)
5-9
5.12 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 a little higher, say 33 psig. It
will move to the correct reading when the air flow is increased. If the pressure drops
below 30 psig, it may be because too much air is being commanded. At maximum air
flow, 20 SLPM, you may notice that the pressure drops to 29 psig. This is normal.
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 a little higher, say 33 psig. It
will move to the correct reading when the air flow is increased. If the pressure drops
below 30 psig, it may be because too much air is being commanded. At maximum air
flow, 20 SLPM, you may notice that the pressure drops to 29 psig. This is normal.
5.13 Hydrocarbon Scrubber (option)
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 M701 control PCB. The controller reads the thermocouple voltage, compensates for
cold-junction temperature and modulates the heater to maintain a constant cartridge
temperature. (See Appendix, drawing 00257).
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 M701 control PCB. The controller reads the thermocouple voltage, compensates for
cold-junction temperature and modulates the heater to maintain a constant cartridge
temperature. (See Appendix, drawing 00257).
The operating temperature of the cartridge is 300ºC. The temperature can be verified by
measuring the thermocouple voltage at J12, the terminal block at the edge of the board
nearest the Hydrocarbon Scrubber. The positive pin is clearly marked. 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. Pot R3, near the top right corner of the PCB,
controls the temperature set-point. (Clockwise to increase.) LED DS1 blinks when the
temperature is at the set-point. LED DS2 is an alarm and will be ON if the thermocouple
is OPEN. Pot R4 has no effect in this application.
measuring the thermocouple voltage at J12, the terminal block at the edge of the board
nearest the Hydrocarbon Scrubber. The positive pin is clearly marked. 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. Pot R3, near the top right corner of the PCB,
controls the temperature set-point. (Clockwise to increase.) LED DS1 blinks when the
temperature is at the set-point. LED DS2 is an alarm and will be ON if the thermocouple
is OPEN. Pot R4 has no effect in this application.
CAUTION
The air exiting the scrubber is at 300
C (575F). This hot air is
cooled in the copper tubing before it enters the NO scrubber.
This 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.
become contaminated or poisoned over time so we recommend that the scrubber be
replaced once per year or sooner.