shall have a storage capacity not less than 20 percent in excess of that
required for the fully-charged system. Each receiver shall be equipped
with inlet, outlet drop pipe, drain plug, purging valve, relief valves of
capacity and setting required by ASHRAE 15, and two bull's eye liquid-level
sight glasses. Sight glasses shall be in the same vertical plane, 90
degrees apart, perpendicular to the axis of the receiver, and not over 75
mm 3 inches horizontally from the drop pipe measured along the axis of the
receiver. In lieu of bull's eye sight glass, external gauge glass with
metal glass guard and automatic closing stop valves may be provided.
2.6.15
Chiller Purge System
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NOTE: Refrigeration systems which operate below
atmospheric pressure (i.e., R-123 machines) will
require a refrigerant purge piping system. Indicate
the routing of the piping on the drawings. Require
the Contractor to delete the piping if a purge
system is not required for the type of chiller that
is to be provided. Indicate that it will be the
Contractor's responsible to size the piping based
upon the chiller manufacturer's recommendations.
Purge discharge piping may be connected to the
pressure-relief piping on the chiller side of the
piping's vibration isolators.
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Chillers which operate at pressures below atmospheric pressure shall be
provided with a purge system. Purge system shall automatically remove air,
water vapor, and non-condensible gases from the chiller's refrigerant.
Purge system shall condense, separate, and return all refrigerant back to
the chiller. An oil separator shall be provided with the purge system if
required by the manufacturer. Purge system shall not discharge to occupied
areas, or create a potential hazard to personnel. Purge system shall
include a purge pressure gauge, number of starts counter, and an elapsed
time meter. Purge system shall include lights or an alarm which indicate
excessive purge or an abnormal air leakage into chiller.
2.6.16
Tools
One complete set of special tools, as recommended by the manufacturer for
field maintenance of the system, shall be provided. Tools shall be mounted
on a tool board in the equipment room or contained in a toolbox as directed
by the Contracting Officer.
2.7
ABSORPTION LIQUID CHILLER
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NOTE: Perform a life cycle cost analysis to
determine the most economical type (single- or
two-stage) of absorption unit to specify. The
initial cost of a two-stage chiller is typically
much higher than a single-stage machine, however a
two-stage chiller will provide a substantial amount
of energy savings over the life of the equipment.
Minimum efficiencies will either be presented in
this paragraph or on the design drawings. Delete
the efficiency ratings in this paragraph if
SECTION 15620A
Page 36
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