Specifications

36 Catalog WSC/WDC-4
Pumpdown
Pumpout systems provide a means to collect and contain the refrigerant charge without loss,
when the access to internal chiller components is required for service.
McQuay condensers are sized to hold the entire unit refrigerant charge when not more than 90%
full at 90°F (32°C) ambient temperature. They are equipped with a tight-seating check valve at
the hot gas inlet and a manual shutoff valve in the liquid outlet. These valves, coupled with the
condenser design, satisfy the stringent requirements of the U.S. Department of Transportation for
refrigerant shipping containers, as well as ASME vessel codes. When service is required, the
refrigerant charge can be pumped down into the condenser by compressor operation and use of a
refrigerant transfer unit. All dual compressor units and single compressor units equipped with an
optional suction shutoff valve can also be pumped down to the evaporator. Elimination of the cost
and space requirements of an external pumpout system is a major McQuay advantage.
Electronic Expansion Valves
Controlled refrigerant flow over the entire capacity range saves energy and dollars.
Cooling loads and condenser water temperatures can change constantly. Refrigerant float valves
and orifices on competitive chillers are typically selected for peak load and peak condenser water
temperatures and offer only partial control of refrigerant flow at operating conditions experienced
over 95% of the time.
On McQuay chillers, modern, electronic or thermal expansion valves (depending on unit size)
meter refrigerant flow in direct response to load and unit conditions. In doing so, full utilization
of compressor, evaporator, and condenser efficiency over the entire operating range is achieved.
Intermittent refrigerant flood-back and excessive superheat characteristic of orifices and floats are
greatly reduced.
Factory Performance Test
Fast and trouble-free startup and operation.
All McQuay chillers are factory tested on ARI certified, microprocessor controlled, test stands.
The test stand microprocessors interface with the chiller MicroTech II controls, allowing
monitoring of all aspects of the test stand and chiller operation.
The test procedure starts with dehydration and evacuation of the refrigerant circuit and charging
with refrigerant and lubricant. This is followed by a run test at job conditions of flow and
temperature. Compressors must meet a stringent 0.14 in/sec vibration limit and the entire unit
must pass a moisture limit of 30 ppm. The testing helps ensure correct operation prior to
shipment, and allows factory calibration of chiller operating controls.