Page 10 – Bulletin 30-21
Upon re-energizing the solenoid coil, the low pressure port
of the 180 opens and allows instantaneous relief of pressure
under the thermostatic expansion valve diaphragm and nor-
mal operation of the thermostatic expansion valve.
APPLICATION
The Type 180 Solenoid Pilot Control may be connected to any
number of thermostatic expansion valves as large as those
nominally rated at 132 tons on Refrigerant 134a and 180 tons
on Refrigerant 22. Thus one Solenoid Pilot Control simultane-
ously controls the action of all expansion valves on one evap-
orator or system of evaporators. See Figure 11.
NOTE: Since the thermostatic expansion valve Types
V and W have an extended neck between the thermo-
static element and the valve body, a relatively large
quantity of liquid refrigerant resides at this point during
the off-cycle (Type 180 de-energized). Upon re-energiz-
ing the Type 180 control this liquid must boil off if the
TEV is installed so that the “neck” volume is NOT free
draining. The consequence of such an arrangement is
chilling of the thermostatic element and possible gas
charge condensation or migration.
Therefore, we recommend that Types V or W thermo-
static expansion valves (with gas or Type “P” ther-
mostatic charges), when installed with the Type 180
solenoid pilot control, be placed in an upright position
and at a point above the suction line so that the volume
under the diaphragm is free draining.
The Solenoid Pilot Control is actuated in the same manner
as a liquid line solenoid valve, e.g. with a thermostat, a pres-
sure switch, or by manual control. Since the Type 180 design
requires that the liquid line pressure during the off-cycle be
slightly higher than the expansion valve bulb pressure, certain
types of applications require special precautions.
Comfort Cooling Applications
Sporlan thermostatic expansion valves for comfort cooling
applications are generally supplied with Type P air condition-
ing charged thermostatic elements. These charges limit the
maximum operating or opening pressure during the off-cycle,
as well as during the running cycle. The table lists these stan-
dard maximum operating pressures at an approximate 60°F
(16°C) saturated evaporator temperature.
Refrigerant
Standard Maximum
Operating Pressure
12, 134a 50 psig (3.5 bar)
22 90 psig (6.2 bar)
External Equalizer
Connection
Figure 11
Therefore, during the off-cycle the receiver ambient tempera-
ture needs to be only slightly higher, 65°F (18°C) or more, to
maintain a higher liquid line pressure and to ensure satisfac-
tory Solenoid Pilot Control operation.
Commercial or Low Temperature
Refrigeration Applications
This type of application requires that the expansion valve and
sensor bulb be installed within the refrigerated space, so the
bulb temperature will be the same as the evaporator during
the off-cycle. Not only will this prevent compressor flood-back
on start-up, but it will help ensure a liquid line pressure high-
er than the bulb pressure to keep the expansion valve closed
tight during the off-cycle.
Comfort Cooling Application (Intermittent Operation)
In certain locales during mild weather, wide variations
between night and day temperatures can create unusual sys-
tem pressure conditions. This occurs when the receiver, hence
the liquid line pressure, falls below the maximum thermo-
static expansion valve operating pressures listed above. This
is liable to occur when the receiver is located on the outside
of the building or is subjected to unusually low ambient tem-
peratures. Proper attention to receiver location can minimize
the possibility.
Other Applications
On other applications where the Solenoid Pilot control may be
applied, care must be exercised to maintain the correct liquid
line – expansion bulb pressure relationship. If the expansion
valve bulb is located near heating coils or any other location
warmer than the receiver location, trouble may occur. During
the off-cycle, the bulb pressure for expansion valves with
thermostatic charges other than the Type P air conditioning
charge will rise and open the valve.
This will tend to flood the evaporator; and, if the compressor
is on pressure control, cause it to run for a short period of time
when cooling is not required. Therefore, proper attention to
component location is important to ensure correct operation
of the Type 180 Solenoid Pilot Control.
Recommendations
Where the unusual conditions exist as previously described,
and where normal location precautions are not feasible,
Sporlan recommends that a conventional liquid line sole-
noid valve be installed instead of the Type 180 Solenoid Pilot
Control.
All refrigeration and air conditioning systems should be
protected from moisture and other system contaminants by
the Sporlan Catch-All® Filter Drier. When using the Type 180
Solenoid Pilot Control, the expansion valve is used to shut off
the liquid line in place of a standard liquid line solenoid valve.
Therefore, it is essential that the system be free of these con-
taminants which might prevent the thermostatic expansion
valve from seating tight.
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