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The sizing of the purge orifice is also important to the performance of a PSA system.
The orifice must be large enough to admit sufficient air to purge the off-line tower, but
not too large to be wasteful of the dry or purified air. Please note that the operating
pressure is closely associated with the orifice sizing, since both the orifice aperture
dimension and pressure determine the quantity of purge air.
The purge orifice size of a particular unit is indicated by the last 2-3 digits of the model
number (found on the product label). The orifice number for the
PHF, PCDA, PHCA
and
PCME
models is also stamped on the top of the purge orifice itself. For the
PCR,
PMD,
and
TOC
models, the orifice size is stamped on the outlet shuttle valve body.
The outlet flow should be regulated with a throttle valve and measured with a flow meter
to ensure the capacity of the dryer or adsorber is not being exceeded. PUREGAS offers
flow meters with built-in flow control valves for this purpose.
IMPORTANT!
Each compressed air dryer and adsorber is sized for specific operating conditions. If
additional flow is required or the operating pressure decreases, the output performance
will be negatively affected unless the orifice diameter is changed appropriately.
Depending on the magnitude of the change, the size of the desiccant chambers may
also need to be increased. Please consult the product sizing charts or contact the
factory for more information.
Other Operating Issues
At the beginning of each purge cycle, there will be an audible exhaust through the
solenoid valve. This sound can be made quieter by the use of purge mufflers (standard
on most models) or a sound suppression kit for virtually noiseless operation. Please
contact PUREGAS for more information on this option.
The exhaust stream may also be piped to a remote location. If this is done, it is
important that the exhaust piping is oversized to prevent back-pressure on the purge
stream; restricting the purge flow will prevent full regeneration of the desiccant chamber
and lead to reduced performance.
The heat of adsorption and the operation of the solenoid valves will cause the unit to
become warm to the touch. This is normal.
To prevent potential electrical shock, the timer cover should not be removed for
maintenance until power is disconnected from the unit. Likewise, the unit should be
completely depressurized prior to service.
