7
The purge adjustment manifold consists of the Purge Adjustment Valve, the Purge
Pressure Gauge and the Purge Orifice. When the right tower is the drying tower
(pressurized) and the left tower is depressurized (0 PSIG), manually adjust the
Purge Adjustment Valve until the gauge reading on the purge pressure gauge
matches the Purge Pressure Gauge setting listed on the laminated tag affixed to
the Orifice Plate Assembly.
6.5
TOWER REPRESSURIZATION
Upon completion of tower regeneration, and prior to the Inlet Flow Valves changing
position to switch towers, the regenerated tower must be repressurized.
Repressurization is accomplished by closing the appropriate Purge Valve. Closing
the Purge Valve allows the regeneration air to begin to pressurize the tower. In
addition to the regeneration air, the Repressurization Valve, (standard on -80°F and
-100°F dew point and high pressure dryers; optional on -40°F dew point dryers)
opens allowing some additional air from the outlet of the dryer to ensure adequate
pressurization. During normal tower regeneration, the Repressurization Valve is
held closed so that the only source of air for regeneration passes through the purge
adjustment assembly.
6.6
VALVES
Solenoid valves are electrically actuated valves used as the Inlet Flow Valves and
the Purge Valves for 150 psig units. These valves are normally closed valves.
When the valves are de-energized, they default to a closed position. In the de-
energized state, the Inlet Flow Valves keep the air from entering the towers and the
Purge Valves keep air from being purged from the system. For dryers rated for 300
psig, the Inlet Flow Valves and Purge Valves are replaced by actuated ball valves.
Outlet Check Valves are single-direction check valves that will allow flow in the
direction shown on the P&ID, but not allow flow in the opposite direction.
6.7
TIMER OPERATION
All timing functions are performed by the Solid State Timer (SST). The SST does
not require any adjustment. In the event of any SST malfunction consult factory.
Failure to re-pressurize prior to tower switchover will result in shocking the
desiccant material and cause premature desiccant dusting.
The right tower must be the drying tower for proper purge adjustment setting.
When the left tower is the drying tower, the Purge Adjustment Gauge will read
close to line pressure.
NOTICE
NOTICE
