Head Pressure Control Valves

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Kathleen Gaines
5 years ago
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Head ontrol s High and Low mbient Stability The design of air conditioning systems utilizing air cooled condensing units involves two main

If the condensing unit is properly sized, it will operate satisfactorily during extremely high ambient temperatures.

the solution to low ambient operation is more complex.

Since the pressure differential across the thermostatic expansion valve port affects the rate of refrigerant flow, low head pressure

Failure to have sufficient head pressure will result in low suction pressure and/or iced evaporator coils.

Insufficient flow through the TEV will cause a low suction pressure.

liquid flow from the condenser to the receiver, and at the same time divert hot gas to the inlet of the receiver.

1 Head ontrol s High and Low mbient Stability The design of air conditioning systems utilizing air cooled condensing units involves two main problems that must be solved if the system is to operate reliably and economically high ambient and low ambient operation. If the condensing unit is properly sized, it will operate satisfactorily during extremely high ambient temperatures. However, some units will be required to operate at ambient temperatures below their design dry bulb temperature during most of the year, the solution to low ambient operation is more complex. Without good head pressure control during low ambient operation, the system can experience both running cycle and off-cycle problems. Since the pressure differential across the thermostatic expansion valve port affects the rate of refrigerant flow, low head pressure generally causes insufficient refrigerant to be fed to the evaporator. Failure to have sufficient head pressure will result in low suction pressure and/or iced evaporator coils. The primary off-cycle problem is refrigerant migration to the condenser. Insufficient flow through the TEV will cause a low suction pressure. The typical method of maintaining normal head pressure in a refrigeration system during periods of low ambient temperature is to restrict liquid flow from the condenser to the receiver, and at the same time divert hot gas to the inlet of the receiver. This backs liquid refrigerant up into the condenser reducing its capacity which in turn increases the condensing pressure. t the same time the hot gas raises liquid pressure in the receiver, allowing the system to operate normally. Head ontrol for systems with air cooled condensers can be accomplished using one of several valve options; the non-adjustable ORO-5, the adjustable ORI/ORD combination, or the economical L series. For all requests, consult your nearest Wholesaler or contact us on: 148 RE atalogue R & / gal-1/uk - Ed. November 2011

2 Nomenclature/Ordering Instructions L L DS - 100/80-3/8 " X 3/8 " X 3/8 " Low mbient ontrol Size Dual Setting Omit for standard dome element Setting (s) (psig) - Specify one setting for ondensed L /8" X 5/8" X 3/8 " ODF Low mbient ontrol Size Setting(s) (psig) ondensed Solder s ORI ORI /225-7/8" ODF - With Strainer - H Open on rise of Inlet Port Size Eighths of an Inch Nominal djustment Range (psig) Solder Inlet Strainer (Optional) Designates High ellows ORO ORO /8" ODF - With Strainer Open on rise of Outlet Port Size Eighths of an Inch Setting (psig) Solder Inlet Strainer (Optional) ORD-4 ORD Open on rise of Differential Port Size Eighths of an Inch Opening Differential (psi) Materials and onstruction Details L-4,-5, ORI-6, ORD-4 ORO 6 ody Material rass rass opper rass Seat Metal to Metal Metal to Metal Metal to Metal Metal to Metal Element Type and Material Type of Joints Domed Steel Remote ulb only for R410 L-5-HP, -HP valves Knife Edge, Metal to Metal ellows - rass Hermetic onstruction ellows - rass Hermetic onstruction Diaphragm Stainless Stee Hermetic onstruction s ODF opper ODF opper ODF opper ODF opper MRP Max External Leakage UL ompatibility 46.9 barg (680 psig) R410 only L-4 =34.5 barg (500 psig) L-5, = 31 barg (450 psig) 31 barg (450psig) 31 barg (450psig) 31 barg (450psig) psig ( bar) S-5460 ll HF, HF, Refrigerants and blends 149 RE atalogue R & / gal-1/uk - Ed. November 2011

3 Selection Tables Low mbient apacities - kw of Refrigeration apacities are based on evaporator temperature, 35 condenser, 6 subcooled liquid. Refrigerant Setting (bar) (12.4 bar) 134a (6.9 bar) R-410 (20.3 bar) Minimum mbient Design Temp. Drop ccross (bar) For all requests, consult your nearest Wholesaler or contact us on: L-4 L-5 L ORO-5 ORD RE atalogue R & / gal-1/uk - Ed. November 2011

4 Selection Tables Low mbient WINTER apacities - kw of Refrigeration apacities are based on evaporator temperature, 35 condenser, 6 subcooled liquid. Refrigerant Setting (bar) Minimum mbient Design Temp. Drop ccross (bar) L-4 L-5 L ORO-5 ORD (14.5 bar) 507 (14.5 bar) For all requests, consult your nearest Wholesaler or contact us on: 151 RE atalogue R & / gal-1/uk - Ed. November 2011

5 Selection Tables High mbient SUMMER apacities - kw of Refrigeration apacities are based on evaporator temperature, 43 condenser, 6 subcooled liquid. Refrigerant Setting (bar) (12.4 bar) 134a (6.9 bar) 410 (20.3 bar) Drop ccross (bar) L-4 L-5 L ORO-5 ORI-6 ORI ORD High mbient SUMMER apacities - kw of Refrigeration apacities are based on evaporator temperature, 43 condenser, 6 subcooled liquid. Refrigerant Setting (bar) 404 (14.5 bar) 507 (14.5 bar) Drop ccross (bar) L-4 L-5 L ORO-5 ORI-6 ORI ORD '7.2 3' '5.4 6' ' For all requests, consult your nearest Wholesaler or contact us on: 152 RE atalogue R & / gal-1/uk - Ed. November 2011

6 Dimensions Specifications and Dimensions Type (1) (2) Standard Factory Setting bar ORI-6-65/225-H 8.3 s ODF Solder (Inches) Dimensions - mm Weight kg Inlet(s) Outlet D E F G I Net Ship Replacement Parts 5/8 5/ /8 7/ /8 1-1/ ORI-65/225-H /8 1-3/ ORD /8 5/ ORO-5 6.9, 12.4 or /8 1-1/ (1) 5/8 (2) 5/8 (1) 5/8 (2) 7/8 5/ Inlet Strainer / ORI ORO ORD-4 92 mm D 6 For all requests, consult your nearest Wholesaler or contact us on: 153 RE atalogue R & / gal-1/uk - Ed. November 2011

7 Dimensions Specifications and Dimensions Type L-4 L-4-DS L-5 L Standard Factory Setting bar 6.9, 12.4 or 14.5 s ODF Solder (Inches) Dimensions - mm Weight kg Inlet(s) Outlet D E F G I Net Ship 1/4 1/ /8 3/ /2 1/ /8 3/ /2 1/ /2 1/ /8 5/ Dome Element 155 ulb Element /8 7/ /8 1-1/ (1) 1-3/8 (2) 7/8 (1) 1-3/8 (2) 1-1/8 7/ / (1) (2) L-4 L-4-DS L-5 & mm 92 mm 49.3 mm 92 mm R3L E D D E E D3L D 102 mm 19 mm For all requests, consult your nearest Wholesaler or contact us on: 154 RE atalogue R & / gal-1/uk - Ed. November 2011

8 Order Selection Guide Head ontrol s Type onncetions - Inches / Standard Factory Setting (PSI) Standard Factory Setting (bar) Part Number L-4 3/8 ODF 3/8 ODF /2 ODF 1/2 ODF /8 ODF 3/8 ODF /2 ODF 1/2 ODF L-4-DS 3/8 ODF 3/8 ODF / /12.4 1/2 ODF 1/2 ODF L-4-HP 1/2 ODF 1/2 ODF 295HP /8 ODF 7/8 ODF /2 x 1/2 ODF, L-5 5/8 x 5/8 ODF, 100, /12.4 Special order valve 7/8 x 7/8 ODF, 1-1/8 x 1-1/8 ODF L-5-HP 295HP L 7/8 x 7/8 ODF, 1-3/8 x 1-3/8 ODF 100, /12.4 Special order valve L-HP 1-3/8 ODF 7/8 ODF HP /8 ODF 1-1/8 ODF ORI-6-65/225H 7/8 ODF 7/8 ODF /8 ODF 1-1/8 ODF ORI-65/225H 1-1/8 ODF 1-1/8 ODF /8 ODF 1-3/8 ODF ORD ORO /8 ODF 7/8 ODF /8 ODF 7/8 ODF ORO /8 ODF 7/8 ODF /8 ODF 7/8 ODF ORO-5 OROD-5 5/8 x 5/8 ODF, 5/8 x 7/8 ODF Special order valve 6 Maximum Drop etween ompressor and - bar elow Head omponent Selection ORO-50 or -180 ORD-4 & ORI ORO-50 or -180 ORD-4-25 & ORI ORO-50 or -180 ORD-4 & ORI OROD-50 or -180 ORD-4-35 & ORI 155 RE atalogue R & / gal-1/uk - Ed. November 2011

These valves can also be ordered as a bidirectional valve, allowing control of flow in both directions for use on heat pump applications.

These valves can also be ordered as a bidirectional valve, allowing control of flow in both directions for use on heat pump applications. Type EBS/O Type EBS and O valve is a brass bar body, externally adjustable valve with ODF solder connections. The thermostatic element is replaceable, and the inlet connection has a permanent 12 mesh strainer.