Parker Sporlan B5D Series Installation And Servicing Instructions

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Parker Sporlan B5D Series Installation And Servicing Instructions Manual pdf 10 page image

Page 10 – Bulletin 30-21Upon re-energizing the solenoid coil, the low pressure portof the 180 opens and allows instantaneous relief of pressureunder the thermostatic expansion valve diaphragm and nor-mal operation of the thermostatic expansion valve.APPLICATIONThe Type 180 Solenoid Pilot Control may be connected to anynumber of thermostatic expansion valves as large as thosenominally rated at 132 tons on Refrigerant 134a and 180 tonson 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 TypesV and W have an extended neck between the thermo-static element and the valve body, a relatively largequantity of liquid refrigerant resides at this point duringthe off-cycle (Type 180 de-energized). Upon re-energiz-ing the Type 180 control this liquid must boil off if theTEV is installed so that the “neck” volume is NOT freedraining. The consequence of such an arrangement ischilling of the thermostatic element and possible gascharge 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 180solenoid pilot control, be placed in an upright positionand at a point above the suction line so that the volumeunder the diaphragm is free draining.The Solenoid Pilot Control is actuated in the same manneras a liquid line solenoid valve, e.g. with a thermostat, a pres-sure switch, or by manual control. Since the Type 180 designrequires that the liquid line pressure during the off-cycle beslightly higher than the expansion valve bulb pressure, certaintypes of applications require special precautions.Comfort Cooling ApplicationsSporlan thermostatic expansion valves for comfort coolingapplications are generally supplied with Type P air condition-ing charged thermostatic elements. These charges limit themaximum 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 MaximumOperating Pressure12, 134a 50 psig (3.5 bar)22 90 psig (6.2 bar)External EqualizerConnectionFigure 11Therefore, during the off-cycle the receiver ambient tempera-ture needs to be only slightly higher, 65°F (18°C) or more, tomaintain a higher liquid line pressure and to ensure satisfac-tory Solenoid Pilot Control operation.Commercial or Low TemperatureRefrigeration ApplicationsThis type of application requires that the expansion valve andsensor bulb be installed within the refrigerated space, so thebulb temperature will be the same as the evaporator duringthe off-cycle. Not only will this prevent compressor flood-backon start-up, but it will help ensure a liquid line pressure high-er than the bulb pressure to keep the expansion valve closedtight during the off-cycle.Comfort Cooling Application (Intermittent Operation)In certain locales during mild weather, wide variationsbetween night and day temperatures can create unusual sys-tem pressure conditions. This occurs when the receiver, hencethe liquid line pressure, falls below the maximum thermo-static expansion valve operating pressures listed above. Thisis liable to occur when the receiver is located on the outsideof the building or is subjected to unusually low ambient tem-peratures. Proper attention to receiver location can minimizethe possibility.Other ApplicationsOn other applications where the Solenoid Pilot control may beapplied, care must be exercised to maintain the correct liquidline – expansion bulb pressure relationship. If the expansionvalve bulb is located near heating coils or any other locationwarmer than the receiver location, trouble may occur. Duringthe off-cycle, the bulb pressure for expansion valves withthermostatic charges other than the Type P air conditioningcharge will rise and open the valve.This will tend to flood the evaporator; and, if the compressoris on pressure control, cause it to run for a short period of timewhen cooling is not required. Therefore, proper attention tocomponent location is important to ensure correct operationof the Type 180 Solenoid Pilot Control.RecommendationsWhere 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 PilotControl.All refrigeration and air conditioning systems should beprotected from moisture and other system contaminants bythe Sporlan Catch-All® Filter Drier. When using the Type 180Solenoid Pilot Control, the expansion valve is used to shut offthe 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 expansionvalve from seating tight.