Pneumatic Controller (PC)
#619985 Shown
TROUBLESHOOTING SFD AIR DRYER SYSTEMS
MLT, PLC and Pneumatically Controlled Operation/Cycle & Problem Scenarios
Micro Logic Timer
(MLT) manages regeneration cycles by energizing and de-
energizing the air control valve at two-minute intervals. However,
when the air dryer is initially powered on, the MLT begins a startup
sequence of four ten-second cycle intervals, and when completed, MLT
begins cycling every two minutes.
An LED on the MLT will be "on" during energized (charge) cycle and "off" during de-energized
(regeneration) cycle. When LED is on, the left desiccant cartridge receives wet air and the right desiccant
cartridge regenerates. After two minutes MLT (dryer) switches, LED is off as left canister now begins
regeneration process and right desiccant cartridge receives wet air. A light flow of air from the desiccant
cartridge through dryer’s exhaust port is normal during regeneration cycle. There should be no venting of
air from desiccant cartridge when receiving wet air.
When an SFD cycles, there will be a momentary burst of air from one SFD exhaust port (muffler). This is
normal and will occur each time dryer cycles. Four cartridge MLT systems will have two cartridges
regenerating one from each dryer unit, e.g., cartridges 1, 3 charge cycle, cartridges 2, 4 regeneration cycle
Programmable Control Box
(PLC) controls regeneration cycles by
energizing and de-energizing air control valves at 45-second intervals.
A flow rate of approximately 3.5 cfm (99.1 lpm) air from ONE
exhaust port (muffler) per dryer row occurs as normal regeneration air
flow for desiccant bed drying. This air flow will alter in 45 second
intervals from one exhaust port(s) to other in conjunction with PLC
cycles. With dryer cycles (switching from one cartridge to other), a
momentary burst of air expels from one exhaust port as remaining cartridges continue to receives wet
contaminated air. This short burst of air is normal occurring each time dryer cycles.
Pneumatically Controlled (PC)
SFD dryer systems regenerate by
energizing and de-energizing air control valves at approximately one
(1)-min intervals.
A continuous flow rate of approximately 3.5 cfm (99.1 lpm) air from
ONE exhaust port (muffler) per dryer row occurs as normal
regeneration air flow for desiccant bed drying. This air flow will alter
in 60-second intervals from one exhaust port(s) to other in
conjunction with Pneumatic cycles. When dryer cycles (switching
from one cartridge to other) a short burst of air expels from one
exhaust port as remaining cartridges continue to receive wet contaminated air. This short burst of air is
normal occurring each time dryer cycles.
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