HDK-MT350_EN_06
35
Shutting down and restarting the dryer
In the following cases, the dryer must be fully shut down and depressurised:
In the event of an emergency or malfunction
For maintenance
For disassembly
Warning - damage to dryer after power failure!
The two main valves (V1/V2) open in the event of the power failing. This
can cause sudden pressure equalisation if one tower is pressurised while
the other is regenerating. This pressure equalisation between the towers
can damage the valves and the desiccant bed.
The dryer may not be shut down correctly after the power supply has
been interrupted or in the case of emergency. In this case the two inlet
valves are open and both expansion valves are closed.
If malfunctions occur after power failure or an emergency (e.g. poor
dewpoint), a 12-month maintenance routine will be required. The
desiccant and the dust screen should also be checked.
Note:
If the unit is equipped with a compressor synchronisation system,
first switch off the compressor and then wait until the dryer has
reached the standby phase before switching it off with the ON/OFF
switch.
This ensures that the regeneration cycle is completed, and that the
pressure in both vessels is at the same level.
As soon as the dryer is switched on again, the programme continues
the cycle from the point at which it has been stopped.
Shutting down and depressurising the dryer
Disconnect dryer from the compressed air system.
► Close the pressure outlet valve installed by the operator.
► Close the pressure inlet valve installed by the operator.
Depressurise dryer
► Leave the dryer switched on until each vessel has run through an expansion
phase.
The vessels are relieved from pressure one-after another due to the expansion
phase.
► Check the pressure relief of the dryer on both pressure gages. They should
indicate "0" bar.
