APC UCCS Temperature Control - Manual (Page 18)

JANUARY 2008 UCCS STANDARDS 15950-18
2. Sizing Criteria:
a. Two-position service: Line size.
b. Two-way modulating service: Pressure drop across the valve in a wide-open
position, with full flow through the valve, shall be equal to 50% of the available
pressure differential between the mains, with a minimum of 4 psi.
c. Three-way Modulating Service: Pressure drop across the valve in a wide-open
position, with full flow through the valve, shall be equal to twice the pressure
drop through the heat exchanger (load), with a 3 psi minimum..
3. Construction:
a. Valves 1/2" through 2" shall be bronze body or cast brass ANSI Class 250,
spring loaded, Teflon or ring packing, and stainless steel stems. Two-way valves
to have replaceable composition disc.
b. 2-1/2" valves and larger shall be cast iron ANSI Class 125 with guided plug,
stainless steel stems and Teflon or ring packing.
4. Water valves shall fail as specified in the Control Sequences section .
5. Evaporative Cooler Drain and Fill Valves:
a. Valve normal position shall be as shown on the drawings.
6. For systems with glycol solutions, provide documentation that the valve components
in contact with the fluid are compatible with it.
2.04 CONTROL DAMPERS [NOTE TO CONSULTANT: INCLUDE WORDING IN THE
AIR-HANDLING UNIT SECTION OF THE SPECIFICATION STATING THAT
D A M P E R S P R O V I D E D W I T H E Q U I P M E N T S H A L L M E E T T H E
REQUIREMENTS LISTED BELOW]
A. Motorized dampers, unless specified elsewhere, shall be as follows:
1. Damper frames shall be 13 gauge galvanized steel channel or 1/8" extruded aluminum
with reinforced corner bracing.
2. Damper blades shall not exceed 8" in width or 48" in length. Blades are to be suitable
for medium-velocity performance (2,000 fpm). Blades shall be not less than 16
gauge.
3. Damper shaft bearings shall be as recommended by manufacturer for application.
4. All blade edges and top and bottom of the frame shall be provided with replaceable
butyl rubber or neoprene seals. Side seals shall be spring-loaded stainless steel. The
blade seals shall provide for a maximum leakage rate of 10 CFM per square foot at 4"
w.c. differential pressure. Pressure drop shall not exceed 0.04" w.c. for airfoil blades,
or 0.10"w.c. for regular blades, at a wide open face velocity of 1,500 FPM.