Brochure

Catalog CIC-2003-1/US
Parker Hannifin Corporation
Climate & Industrial Controls Group
Cleveland, OH
187
Service
& Check
Valves
Thermostatic and Constant Pressure (Automatic) Expansion Valves
TXVs & AXVs
Thermal Electric ValvesInstallation Information
If the line is at some angle other than vertical, the
lower or gravity side is preferable (see the illustration
at the right).
5. Thermistor location on horizontal suction lines is
more common and in some cases (large diameter
low velocity suction lines) permits adjustments to be
made in suction gas saturation (see illustration in
the right column). The best thermistor sensing
positions in horizontal suction lines are generally
between 4 o'clock and 8 o'clock in the lower half of
the suction line, although successful applications
have been made with the thermistor in all axial
locations. As a rule, the thermistor should be
located as high axially in the 4 to 8 o'clock range
as possible on horizontal suction lines using
tolerable suction gas wetness as the limiting
factor.
6. The most important rule regarding the location of
the liquid sensing thermistor on any applications is
simply this; make sure that liquid or wet refrigerant
gas can come into good contact with the thermistor
at all loads. Once a location has been established
on a given application, subsequent units will show
excellent repeatability.
Effects of Ambients and Blowers During Running
Periods – Exposure to fan or blower air movement has
almost no effect on the valve. It will operate properly in
all ambients from -40°F (-40°C) to +150°F (+66°C).
The valve has a normal tendency to lose capacity at
lower ambients and gain capacity at high ambients.
The thermistor, however, generally compensates for
these changes automatically.
Effect of Ambient During Off-Cycle Periods – During
off-cycle periods, the valve will bleed off refrigerant if
exposed to ambients above 70°F (21°C) and will close
off relatively tight if exposed to ambients of less than
70°F. In short, the valve is simply calibrated to close at
70°F with no electrical energy applied.
Off-Cycle System Unloading – The valve can be left
energized 100% of the time, in which case it will com-
pletely and rapidly unload the system during off-cycle
periods.
The valve can be de-energized during off-cycle periods
with the compressor, in which case it will partially
unload the system, depending upon the amount of
charge and the ambient. (See Effect of Ambient
During Off-Cycle Periods above).
Best Thermistor Sensing Positions on Horizontal
Suction Lines
Preferable Location for Thermistor Assembly on
Angled Line
Note: Do not install in vertical lines.