Maintenance - SPX Hankinson HHE Series Instruction Manual

10. MAINTENANCE

WARNING - The heatless desiccant dryer is a pressure-containing
device. De-pressurize before servicing. (See Section 3.3)
NOTE: Level 1 and 2 Controllers are equipped with Service Reminder
functions for filters, desiccant and valves.
10.1 Desiccant Replacement
NOTE: The use of the correct replacement desiccant is necessary
for proper dryer operation. Never use hygroscopic salts of the type
commonly used in "deliquescent " type dryers.
10.1.1 Frequency Of Desiccant Replacement
Desiccant should be replaced whenever the required dew point
cannot be maintained while the dryer is being operated within its
design conditions and there are no mechanical malfunctions. Refer
to Section 11.0 for troubleshooting hints.
NOTE: Desiccant life is determined by the quality of the inlet air.
Proper filtering of the inlet air will extend the life of the desiccant.
Typically desiccant life is 3 to 5 years.
10.1.2 Procedure for Desiccant Charge Replacement
• De-pressurize and de-energize the dryer.
• Remove the fill and drain plugs from desiccant tower and drain
the spent desiccant. Place a container at the base of the vessel
to collect the desiccant. If necessary tap the sides of the vessels
with a rubber mallet to loosen desiccant.
NOTE: Use extreme care when inserting rods or other tools through
the desiccant fill or drain ports to loosen packed desiccant. Internal
flow diffusers at the ends of the desiccant beds can be damaged
or punctured by sharp instruments. These diffusers are necessary
to distribute the airflow and keep the desiccant beads within the
tower. Desiccant beads in exhaust mufflers, afterfilters, or the piping
connected to the desiccant towers may indicate a perforation of a
diffuser.
• Replace the drain plug using Teflon tape or another pipe thread
sealant suitable for compressed air service.
• Fill the desiccant tower as full as possible with dry desiccant. Do
not tamp or otherwise pack the desiccant.
• Replace the fill plug using Teflon tape or another pipe thread
sealant suitable for compressed air service.
• Repeat this procedure for the other tower.
10.1.3 Insuring Desiccant Dryness
Replacement desiccant is shipped in airtight containers. Keep the
covers on these containers tightly closed until use to avoid moisture
contamination. If desiccant is exposed to air it can be heated in an
oven at 400°F (204°C) for four hours before use. Alternatively, if the
dryer is not refilled with dry desiccant, it may be necessary to operate
the unit with an inlet flow rate of less than 50% of maximum rated inlet
capacity until the desiccant has regenerated fully.
10.2 Purge Mufflers
• Purge mufflers should be checked regularly, changed annually.
Muffler disseminator elements become clogged with desiccant dust
over time, creating back pressure and restricted purge flow.
• Refer to section 9.2.7.
10.3 Valves
• Process and pilot valves should be checked frequently for leaks
and proper operation.
• Purge pressure adjustment valve should be checked frequently
for proper adjustment.
• Refer to section 9.2.8.
10.4 Pilot Air Filter Element Replacement
10.4.1 Frequency of replacement
The pilot air filter contains a filter element that should be changed
yearly. Replacement may be required sooner if pressure drop across
cartridge prevents valves from actuating properly. Pilot air pressure
should be in the range of 60 - 120 psig (4.1 - 8.3 barg) and is controlled
by a pressure regulator that has been set and sealed at 120 psig
(8.3 barg).
WARNING – The pilot air filter housing is a pressure-containing
device, de-pressurize before servicing. Slowly open manual drain
valve on bottom of filter bowl by turning clockwise to verify that
the housing is de-pressurized before removing bowl.
10.4.2 Procedure for element replacement
10.4.2.1 Models 40 through 3000
• Isolate dryer from air supply
• De-pressurize dryer by running dryer and allowing system
pressure to purge to atmosphere. Loss of pilot pressure will
eventually prevent purge/repressurization valves from opening.
Remaining pressure can be vented to atmosphere through the
manual vent on the pilot air filter. The system must be fully de-
pressurized before removing the bowl.
• Remove the filter bowl by turning counterclockwise and then
pulling straight down.
• Clean the filter bowl.
• Replace the element. Reassemble in reverse order.
10.4.2.2 Models 4100 through 5400
• Isolate dryer from air supply
• De-pressurize dryer by running dryer and allowing system
pressure to purge to atmosphere. Loss of pilot pressure will
eventually prevent purge/repressurization valves from opening.
Remaining pressure can be vented to atmosphere through the
manual drain on the pilot air filter. The system must be fully de-
pressurized before removing the bowl.
• Remove the filter bowl by pushing up, turning counterclockwise
and then pulling straight down.
• Clean the filter bowl.
• Replace the element – Pull off the old element and discard. Make
certain O-ring inside top of replacement element is lubricated and
in place and then push element onto filter head.
• Clean and lubricate O-ring at top of bowl and reassemble in
reverse order.
NOTE: Wave spring ends should be pointed down to prevent the wave
spring from interfering with reassembly.
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