9
6.3 Operating Sequence Description
(Refer to P&ID drawing in back of manual)
6.3.1 Fixed Cycle and Standard Cycle
1. Left Tower Regenerating – Right Tower Drying
Valves Opened:
• Left Purge Inlet Valve (V2)
• Left Purge Outlet Valve (V4)
• Right Drying Inlet Valve (V5)
• Right Drying Outlet Valve (V7)
Valves Closed:
• Right Purge Inlet Valve (V1)
• Right Purge Outlet Valve (V3)
• Left Drying Inlet Valve (V6)
• Left Drying Outlet Valve (V8)
Flow:
Hot compressed air flow:
a. Left Purge Inlet Valve (V2)
b. Left Tower – flowing downward as previously
adsorbed moisture is removed from the desic-
cant.
c. Left Tower Purge Outlet Valve (V4)
d. Purge Air Cooler – The compressed air flow
is cooled before being dried.
Cool compressed air flow:
e. Purge Air Separator – removes condensed
water from the air to be dried
f. Right Tower Drying Inlet Valve (V5)
g. Right Tower – flowing upward as the air is
dried
h. Right Tower Drying Outlet Valve (V7) - Dry
air exits the dryer
Fixed Cycle:
The towers switch after the minimum
drying time has expired.
Standard Cycle:
When the Left Tower has heated
through it is fully regenerated and ready for another
drying period. The Left Tower continues to heat until
heated through as detected by the temperature sen-
sor in the lower pipe manifold. Once the Left Tower is
heated through the towers switch once the Minimum
Drying Time expires.
2. Right Tower Drying – Left Tower Regenerating
Operation is as described above except all valves
positions are opposite.
State Transition Conditions
ID
State
Description
Fixed
Cycle
Standard
Cycle
Dew Point Control
Cycle
Manual
Cycle
0
Left Heat (1)
Transition to:
Left Heat (2)
State Timer >
Fixed Heat (1) Time
LT Temperature >
Heat (1) Complete Temperature
LT Temperature >
Heat (1) Complete Temperature
Manual Advance
Button Pressed
1
Left Heat (2)
Transition to:
Left Standby
Drying Timer >
Minimum Drying Time
LT Temperature >
Heat (2) Complete Temperature
LT Temperature >
Heat (2) Complete Temperature
Manual Advance
Button Pressed
2
Left Standby
Transition to:
Right Heat (1)
Drying Timer >
Minimum Drying Time
State Timer > Standby Time
AND
Drying Timer > Minimum Drying Time
Dew Point > Dew Point Control Set Point
AND
Drying Timer > Minimum Drying Time
Manual Advance
Button Pressed
3
Right Heat (1)
Transition to:
Right Heat (2)
State Timer >
Fixed Heat (1) Time
RT Temperature >
Heat (1) Complete Temperature
RT Temp >
Heat (1) Complete Temperature
Manual Advance
Button Pressed
4
Right Heat (2)
Transition to:
Right Standby
Drying Timer >
Minimum Drying Time
RT Temperature >
Heat (2) Complete Temperature
RT Temperature >
Heat (2) Complete Temperature
Manual Advance
Button Pressed
5
Right Standby
Transition to:
Left Heat (1)
Drying Timer >
Minimum Drying Time
State Timer > Standby Time
AND
Drying Timer > Minimum Drying Time
Dew Point > Dew Point Control Set Point
AND
Drying Timer > Minimum Drying Time
Manual Advance
Button Pressed
TABLE 4
State Transition Conditions