Models 590 To 5400 W/ Check Valves - Gardner Denver DGH Series Instruction Manual

3.3.2 Models 590 to 5400 w/ Check Valves

(Refer to Fig. 3-2a.) Compressed air flows through inlet
switching valve (3A) (normally open) to tower (4A) where the air
is dried. After the air is dried it flows through outlet check valve
(5A) and then to the dryer outlet. A portion of the dry air, the
purge stream, branches off from the main air stream prior to the
outlet. The purge stream flow rate is controlled by the
adjustable purge rate valve (6) and the single purge orifice (7).
The purge flow, which has been throttled to near atmospheric
pressure, is directed through purge check valve (5D) to tower
(4B). As the purge flow passes over the desiccant in tower
(4B), it removes the water vapor which was deposited while the
tower was on-line drying. The purge air then passes through
purge and repressurization valve (9B) (normally closed) and
purge muffler (10B) to the atmosphere.
After regeneration, purge and repressurization valve (9B)
(normally closed) closes allowing tower (4B) to re-pressurize
slowly. Adequate repressurization time is allowed so that tower
(4B) is fully re-pressurized before switchover. After a controlled
time period, air inlet switching valve (3B) (normally open) opens
and inlet-switching valve (3A) (normally open) closes, purge
and repressurization valve (9A) (normally closed) then opens.
(Refer to Fig. 3-2b.) Tower (4B) is now drying the main air
stream while tower (4A) is being regenerated by the purge air
stream. The operation of the inlet switching (normally open) and
purge and repressurization (normally closed) valves is
sequenced by the control system located in the electrical
enclosure.
9A
10A
TOWER
9A
10A
1. Tower Pressure Gauges
2. Purge Pressure Gauge
3. Inlet Switching Valves
4. Desiccant Drying Towers
5. Check Valves
6. Adjustable Purge Rate Valve
7. Purge Orifice
Process Stream
Purge Stream
- 5 –
3. Description
OUTLET
5A 5B
8 8
11
6
2
5C 5D
1 1
7
TOWER TOWER
4A 4B
3A 3B 9B
INLET
FIGURE 3-2a
TOWER 4A DRYING
TOWER 4B REGENERATING
OUTLET
5A 5B
8 8
11
6
2
5C 5D
1 1
7
TOWER
4A 4B
3A 3B 9B
INLET
FIGURE 3-2b
TOWER 4A REGENERATING
TOWER 4B DRYING
8. Safety Valves
9. Purge and Repres-
surization Valves
10. Purge Mufflers
11. Moisture Indicator
A & C Left Tower Suffixes
B & D Right Tower Suffixes
3. Description
10B
10B