Brochure

Catalog CIC-2003-1/US
Parker Hannifin Corporation
Climate & Industrial Controls Group
Cleveland, OH
167
Service
& Check
Valves
Thermostatic and Constant Pressure (Automatic) Expansion Valves
TXVs & AXVs
Valve Selection Procedure Thermostatic Expansion Valves
Selection of charge
• Refer to pages 159 and 160 for a full explanation
of charge selection.
• Select a charge which is best suited for the
application. Type “W” charges are good all-purpose
charges, “Z” charges are meant for low temperature
applications, and “X” charges are for applications
requiring a pressure limit.
3. Choose the valve configuration which best suits
the application.
• Select a model which best suits the needs of the
application based on fitting type, size, and orienta-
tion. Consider physical size and type of adjustment
available for each model.
• Determine whether an external equalizer is
necessary. Combined pressure drops of the
distributor and evaporator which exceed 3 psi will
require an externally equalized valve for proper
operation.
• Determine the full model number by combining
the information.
Nomenclature
(Example)
XX
Outlet
Fitting Size
and Type
1/2"
SAE
Inlet
Fitting Size
and Type
3/8"r
SAE
Maximum
Operating
Pressure
(MOP)
100
Valve Charge
See pages
134 and 157.
W
Z
X
X
Refrigerant
See pages
134 and
157.
V
Nominal
Capacity
in Tons
3
External
Equalizer
Omit for
Internal
Equalizer
E
External
Equalizer
Size and Type
1/4"
SAE/ODF
Valve
Model
G
Example of Valve Selection Procedure
1. Determine application information. The following
information was obtained from system design con-
straints. The example application is an R-22 freezer
which operates continuously at a temperature of 15°F.
The evaporator is rated at a 10° TD, therefore the
evaporator temperature is approximately 5°F. There are
no special pressure constraints on the compressor.
• System refrigerant R-22
• System capacity 13,600 BTU/hr (1.13 tons)
• Evaporator temperature 5°F
Evaporator pressure 28 psig
• Evaporator pressure losses
Distributor pressure drop 15 psi (estimated)
Evaporator pressure drop 6 psi (estimated)
• Condenser pressure 225 psig
Liquid line pressure losses 4 psi (estimated)
Liquid temperature 90°F
• Connections required 3/8" SAE liquid line con.
1/2" SAE evaporator con.
• Valve adjustment
requirements Adjustable
• Bypass bleed requirements None
2. Determine the required nominal capacity and
charge for the valve.
Selection of nominal capacity
• Find the correct capacity
table Correct R-22 table on p. 154
• Find the correct evaporator Refer to 0° evaporator
section (closest to 5°F
design temp.)
• Determine available Condenser pressure 225 psig
pressure drop Evaporator pressure - 28 psig
Total pressure drop 197 psig
Subtract losses
Liquid line - 4 psi
Distributor - 15 psi
Evaporator - 6 psi
Net pressure drop 172 psi
• Find correct pressure Refer to 175 psi pressure drop
drop column column
• Find a capacity selection Find that there is a G(E)1
valve rated at 1.16 tons
• Correct table capacity Refer to the liquid temperature
for liquid temperature table for R-22 and find a factor
correction of 1.08
1.16 tons x 1.08 = 1.23 tons
This valve will be operating at
92% capacity
Selection of charge
• Select appropriate charge From evaporator temperature
range on page 135, choose VW
charge
3. Choose the valve configuration that's best for
the application
• Select valve model Choose the G(E)1 for this
example.
• Determine if there is an Pressure drop after the expan-
external eqaulizer sion valve is 11 psi (5 psi + 6
psi). It is necessary for the valve
to be externally equalized,
therefore the model number for
the valve will include the “E”.
• Determine the full model number; put the information together:
GE 1 VW 3/8"R SAE X 1/2" SAE X 1/4" SAE