FORM 160.72-O1 (810)
JOHNSON CONTROLS
10
SECTION 2 - PRINCIPLES OF OPERATION
subcooler section. This is a precaution against tube
freezing, by ensuring that liquid refrigerant is not pres-
ent in the subcooler during chiller pump down opera-
tions or if a major leak occurs.
oM inTerCooling
description
There may be one or two stages of liquid intercooling
furnished with the OM Titan chiller in the primary re-
frigeration circuit between the condenser and the evap-
orator. The intercooler performs several functions. The
primary function is to flash the high pressure condensed
refrigerant to an intermediate pressure corresponding
to the M series multistage compressor’s inter-stage
pressure. Flashing the high pressure liquid at the inter-
mediate pressure reduces the horsepower required to
compress the flash gas. This portion of the flash gas is
only compressed from an intermediate pressure (inter-
stage) to condensing pressure rather than from evapo-
rator (low pressure) to condensing pressure. Secondary
functions are the separation of the flash gas from the
liquid refrigerant and providing a liquid seal between
the high and low sides of the system.
The intercooler consists of a pressure vessel with in-
ternally mounted mesh eliminators, a float assembly,
and baffles. The eliminators, located in the top of the
vessel, separate droplets of liquid refrigerant from the
flash gas before it flows to the compressor inter-stage
port. A low pressure rectangular vane type float valve
assembly maintains a liquid seal between the high and
low side of the system. The pressure drop across the
float valve causes the refrigerant to flash to an interme-
diate pressure lowering the refrigerant’s temperature to
the corresponding temperature. A baffle is installed in
the intermediate chamber over the float ball to mini-
mize the effect of turbulence on the float ball and to aid
in maintaining steady float operation.
Sight glasses and a hand operating device are provided
to permit visual float valve inspection and manual float
valve operation. A thermometer well, located near the
float valve, is used for checking liquid temperatures.
A manway with sight glasses allows for access to the
float valve assembly and adjusting arm.
operation
Liquid refrigerant leaving the level control valve flash-
es to the intercooler pressure (and temperature). Upon
entering the intercooler the liquid refrigerant sepa-
rates from the flash gas. The flash gas returns to the
compressor inter-stage port after passing through the
mist eliminators. The liquid refrigerant, at intermedi-
ate pressure, flows to the float valve. The float valve
will open, maintaining a liquid level in the intercooler,
and allowing refrigerant flow to the evaporator. As the
liquid refrigerant flows through the float valve it is ex-
posed to evaporator pressure and flashes to the corre-
sponding pressure and temperature.
If the OM Titan chiller is equipped with a second stage
intercooler then the liquid leaving first stage intercool-
er is supplied to the second stage intercooler before al-
lowing refrigerant to flow to the evaporator.
Maintenance and service
Maintenance on intercooler consists primarily of keep-
ing the float valve free to assure steady valve opera-
tion. Service consists of replacing an occasional float
ball and arm assembly.
If the system capacity suddenly decreases as indicated
by an increase in secondary refrigerant temperature,
check float valve operation as follows:
If the low pressure float valve sticks in the open posi-
tion, the liquid seal between the compressor interme-
diate pressure and evaporator pressure will be broken
and gas at intermediate pressure, will flow directly into
the evaporator. This will cause a reduction in capacity
with possible increase in suction pressure and possible
refrigerant carryover back to the compressor and in-
creased current (amperage) readings.
If the float valve sticks, move the float up and down by
means of the hand operation device. If this does not cor-
rect the condition it will be necessary to remove system
refrigerant charge before removing the float through
the manway opening to check the working parts and
mechanisms. Inspect the float ball to be sure it is not
collapsed or leaking. A collapsed or leaking ball (filled
with refrigerant) will cause the valve to remain closed.
Содержание YORK OM Titan
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