APC UCCS Temperature Control - Manual (Page 21)

JANUARY 2008 UCCS STANDARDS 15950-21
3. Refrigerant for the dryer shall be R-134A, or approved, non-CFC, alternate.
4. Dryers Shall be adjusted for 6,400 feet above sea level.
C. Filter and PRV Station:
1. Provide a two-stage, aerosol, coalescing autodrain, submicron type air filter assembly
with replaceable element, 99.99% efficient for solids and oil droplets 0.01 micron and
larger at rated capacity. Sized for maximum of 1 psi drop at 80 psig inlet and rated
system capacity, 10 SCFM minimum. Rated working pressure: 150 psig minimum.
Furnish each stage with manual filter bypass and shutoff valves, differential pressure
gauges with color-coded indications for clean/dirty filter conditions, and one spare
filter element. Install with a Grade DX cartridge in the first stage and a Grade BX
cartridge in the second stage. Mount the first stage upstream of the refrigerated air
dryer and the second stage downstream of the dryer.
2. Provide relieving-type pressure-reducing valve suitable for temperature control
service sized for rated system capacity (10 SCFM minimum). Furnish 0-30 psig
control pressure gauge and a 0-50 psig pressure transmitter to be connected
to Delta, on low pressure side of regulator.
3. Filter and/or PRV shall not be integral to, or mounted inside, the refrigerated air dryer.
D. Desiccant Compressed Air Dryer: Where control air lines run outside and are exposed to
ambient temperatures, provide a desiccant air dryer on the lines to take the dewpoint
temperature down to -20°F. Provide with a color-change dessicant and a clear bowl, or
other means of determining when the dessicant is spent. Provide and install isolation valves
on both sides of the dryer, a bypass loop with a shutoff valve, and a manual blowdown
valve adjacent to or incorporated into the cylinder.
2.07 ACTUATORS AND POSITIONERS – PNEUMATIC
A. Low-pressure pneumatic actuators shall be piston-rolling diaphragm type or diaphragm
type.
1. Actuator housings may be molded or die-cast zinc or aluminum. Exception: Actuator
housings for control dampers or control valves may be of high impact plastic construction
with ambient temperature rating of 50 to 140F minimum.
2. Actuator size and spring ranges selected shall be suitable for intended application.
a. Damper actuators shall be selected per manufacturer's recommendations to provide
sufficient closeoff force and to provide smooth modulating control under design
flow and pressure conditions. Furnish a separate actuator for each damper section.
b. On sequencing applications, valve and damper actuators shall be sized for a maximum
of a 2 p.s.i. shift in nominal spring range with ranges selected to prevent overlap.
B. Rack-and-pinion type butterfly-valve actuator shall be totally enclosed with no external
moving parts. The actuator shall be rack and pinion type, self-draining body with spring-
return to provide fail-open or fail-closed action as required. Actuators shall be sized to