20
Purge Tank
The purge tank consists of a refrigerated cooling coil, liquid level switch, liquid level sight
glass, water bleed-off valve, and a non-condensables exhaust port. The non-condensables
are removed from the purge tank via pumpout solenoid valve L4 and the pumpout
compressor. The condensed refrigerant accumulates in the bottom of the purge tank (see
Figure 5 on page 18).
Purge and Refrigerant Drain Back Function
Purge activity is continuous while the purge condensing unit is operating. The purge
condensing unit provides the cooling source to condense the refrigerant vapor as it enters the
purge tank. Accumulation of non-condensables in the purge tank is dependent upon the
presence or absence of air in the chiller condenser. If there is no air in the chiller condenser,
non-condensables will not accumulate in the purge tank. All condensed refrigerant falls to the
bottom of the purge tank where a level of liquid refrigerant is maintained during purge
operation. When the purge condensing unit is operating, liquid is visible in the purge tank
sight glass. The liquid refrigerant level is controlled by liquid level switch LS1 and liq uid return
solenoid valve L3 (see Figure 5 on page 18).
Pumpout System
The pumpout system consists of a 1/20 H.P. diaphragm pumpout compressor, two pumpout
solenoid valves and a flow restrictor device. When sufficient air has accumulated in the purge
tank the purge control energizes and opens the pumpout solenoid valves and starts the
pumpout compressor. Air is slowly pumped from the purge tank through the flow restrictor and
discharged to an emission collection canister, vent line, or the atmosphere. Removing the air
slowly via the restrictor device improves the efficiency of the purge cycle.
Security-Lock
The purge unit is equipped with a simple security lock system that prevents unauthorized
personnel from tampering with certain functions. The pu rge unit comes from the factory
with the security lock enabled (see Dip switch S1 settings starting on page 28).
One example of why the operator may wish to use the “Security Lock” function is that the
purge unit in the ADAPTIVE mode acquires a certain amount of historical data in it’s LOGs
which it then uses to determine when and how often the purge needs to run to purge non -
condensables from the system efficiently. If an unauthorized person were to inadvertently
clear the LOGs the purge unit would then h ave to run many days to re-acquire historical
data. When the “Security Lock” is activated unauthorized entry cannot be made.
Содержание Redi-Purge PRG-113-C3
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