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or flow variation, PUREGAS manufactures various tanks, which will completely
eliminate downstream pressure surges.
IMPORTANT!
For optimum performance, the maximum available operating pressure should be
maintained across the unit -- up to 150 psig for most models (the maximum operating
pressure for the PMD and TOC models is 125 psig). Any pressure reduction or flow
control should be done downstream of the unit.
Instrumentation
The primary purposes of instrumentation in the system are process control and
troubleshooting. The instruments shown in the Recommended Installation Diagram are
therefore in most cases optional, but their initial cost will be quickly justified through
improved process stability and problem analysis.
A simple, inexpensive means of measuring the moisture content of the outlet air stream
can be accomplished with a vial of color-changing crystals. PUREGAS offers such an
accessory, which can be mounted directly to the dryer or adsorber. The crystals will
change from a dark blue (dry) to pink (wet) depending on the moisture content in the air
stream.
For sensitive or remote applications, PUREGAS manufactures an electronic humidity
alarm, which continuously tracks moisture levels and helps prevent costly repairs
caused by moisture damage. It features simultaneous audible and visual alarms, as well
as open- and closed-circuit conditions for integration into a control system.
Electrical Connections and Timer
Before wiring, check the product label for electrical characteristics. Although standard
electrical characteristics are 115 Volts, 50/60 Hz or 230 Volts, 50/60 Hz, most products
are also available in 12 V
DC
and 24 V
DC
.
There is no electrical overload protection in the product and it should be wired into a
protected circuit. While standard on some units, an 8-foot, 3-wire grounded power cord
is available as an optional accessory for all products. The unit can be grounded by
attaching a wire to a timer assembly bracket screw. Please see the Wiring Diagrams
that follow.
As previously described, the solid state timer controls the switching of the solenoid
valves, which in turn direct the air through the unit. All timers are designed with a one-
hour memory; If power is interrupted, the dryer will resume operation at the same point
in the cycle when the power is restored.
The standard timer for the
PHF and PHCA models
simultaneously switches the
solenoid valves every 30 seconds (for a total cycle time of 1 minute). The timer used on
the
PHFR, PCDA and PCME models
maintains the same cycle, but allows a re-
pressurizing period of 3.75 seconds prior to switching chambers. Re-pressurizing helps
