Teledyne API M751H High Performance Zero Air Generator Operation
07773A DCN6833 23
4.2.6 Pressure Relief Valve The pressure relief valve is a safety device designed to limit the maximum pressure
to which the 751H can be subjected. It is set to open at 75-80 psig. This can be quite
loud when the valve opens and sounds like steam escaping. This is normal operation
and does not mean there is a problem with the unit.
CAUTION – SAFETY HAZARD
DO NOT ADJUST THE RELIEF VALVE!
(Contact TAPI Technical Support if there is any concern about proper function).
The Regenerative Dryer consists primarily of two parallel column s of molecular sieve,
in which alternately one column is scrubbing the air while the other is being
regenerated.
The Regenerative Dryer needs no warm-up and operates at full efficiency as soon as
the 751H is turned on. The molecular sieve is not co nsumed and is good for the life
of the instrument.
When the 751H is turned on, a four -way solenoid-operated valve directs high
pressure air to one of the two columns and vents the other column to atmosphere.
Virtually all the water in the high-pressure air is trapped by the molecular sieve. A
portion of the dried air is expanded to atmospheric pressure through a flow controller
and passes in reverse through the second column. By expanding the air, the volume
increases, thus enabling a small amount of dry purge air to evaporate the entrained
water in the second column. The wet purge air leaving the column is routed through a
stainless steel solenoid -operated valve and exhausted through the drain fitting. This
valve will periodically close when the four-way valve switches columns to maintain
system pressure. The majority of the dry air from the first column is conducted on to
the pressure regulator.
The controller toggles the four-way valve at a predetermined interval and the columns
alternate their function. This cycling rate has been selected to provide the optimum
balance of scrubbing efficiency and air usage and is not adjustable.
4.2.8 Pressure Sensor The pressure sensor senses the system pressure directly following the regenerative
dryer and controls four-way valve action through the control board.