Evaporating Pressure Regulating Valve Type KVQ REFRIGERATION AND AIR CONDITIONING. Technical leaflet

Transcription

1 Evaporating Pressure Regulating Valve Type KVQ REFRIGERATION AND AIR CONDITIONING Technical leaflet

2 Contents Page Introduction...3 Features...3 Technical data...4 Ordering...4 Sizing...5 Valve selection...5 Extended capacity table...6 Design...7 Dimensions and weight USCO.PC.320.A1.22 Danfoss Inc. ( USCO / mks),

3 Introduction The Danfoss KVQ is an evaporating pressure regulating valve designed to be mounted in the suction line of commercial refrigeration and air conditioning systems. It is used to maintain a constant pressure corresponding to a desired evaporator temperature. It can also be used to provide different evaporating pressures in two or more evaporators served by one refrigeration circuit. When operated by a Danfoss EKC 367 or EKS 67 controller, the KVQ provides accurate temperature control under a wide range of load conditions. The Danfoss KVQ is similar in operation to a mechanical EPR valve; the difference is the KVQ's electronic actuator. The KVQ actuator uses a heat motor principle. A fluid-charged reservoir is heated, and as the vapor pressure increases, the bellows expands, moving a pin and valve plate. Changes in the suction pressure do not affect valve function because the area of the bellows is much larger than the orifice area. If the supply voltage cuts out, the valve opens. Features Capacity - Ranges up to 5.8 tons (R22) under nominal conditions to cover many applications Electronic Actuator - Receives a modulating voltage signal to ensure precise temperature control - Removable without system pump down for easier service Fail safe design - Opens immediately when actuator voltage is removed. Refrigerants - Use with all CFC, HCFC, and HFC refrigerants Electronic controls - Designed for use with the EKC 367 or EKS 67 electronic control which can provide special functions such as: Defrosting; External alarming; Remote setting of reference temperature; Temperature readout on external display; Limiting evaporating pressure; Approvals UL Listed, file SA 7200 Danfoss Inc. ( USCO / mks), USCO.PC.320.A1.22 3

4 Technical Data Actuator and valve, KVQ Regulating range p e = 0 to 100 psig Refrigerant temperature in regulating range Refrigerant p e = 0 psig p e = 100 psig R F 59 F R 134a 15 F 87 F R 404A 50 F 48 F R 407C 32 F 63 F R F 46 F Refrigerants CFC, HCFC and HFC Other fluorinated refrigerants can be used at the stated temperatures and pressures Maximum ambient temperature During operation: 50 to 105 F During transport: 60 to 150 F Max. working pressure MWP Max. test pressure p' Supply voltage Max. consumption 310 psig 400 psig 24 V pulsating a.c. from controller 30 VA / 24 V a.c. Enclosure NEMA; IP 54 to IEC 529 Cable entry Pg 13.5 During forced closing by hot-gas defrosting Max. closing pressure 250 psig Max. hot gas temperature 250 F Ordering Type Rated capacity 1 ) tons Valve Connection Code no. Actuator Code no. R 22 R 134a R 404A/R 507 R 407C in. KVQ / 8 034L L0105 KVQ / 8 034L L0105 KVQ / 8 034L L0106 KVQ / 8 034L L ) Rated capacity is the valve capacity at evaporating temperature t e = 40 F condensing temperature t c = 100 F pressure drop across valve p = 2 psi 4 USCO.PC.320.A1.22 Danfoss Inc. ( USCO / mks),

5 Valve selection For optimum performance, it is important to select a KVQ valve according to system conditions and application. The following data must be used: The selection table on page 6 assumes a liquid refrigerant temperature of 100 o F ahead of the evaporator. If the valve is being used in a system whose liquid temperature differs from 100 o F by more than 5 o F, a correction factor must be applied to the evaporator capacity (see example). The selection is also dependent on an acceptable pressure drop across the valve. The following example illustrates how selection is made. Refrigerant Evaporator capacity Q e in TR Evaporating temperature t e in F Liquid temperature ahead of expansion valve t l in F Connection size in inches. Example: Refrigerant: R22 Evaporating temp.: t e = 20 o F p e = 43 psig Evaporator pressure: p e = 43 psig Evaporator capacity: Q 0 = 2.0 TR Pressure, rack side of KVQ: P r = 37 psig Liquid temperature: T 1 = 80 o F (ahead of the expansion valve) Step 1 Find the pressure drop across the KVQ. The pressure drop, p, is calculated by the formula p = p e - p r where p e is evaporating pressure, and p r is the suction pressure on the rack side of the KVQ. In our example, the pressure drop across the valve will be: p = = 6 psig Step 2 If necessary, correct the evaporator capacity for the temperature of the liquid entering the evaporator. If liquid temperature is at or below 90 o F or at or above 110 o F, correct the evaporator capacity. Find the correction factor in the table of liquid temperature correction factors on page 6. For liquid temperature less than 80 F, use the factor in the 80 o F column; for liquid temperature greater than 120 o F, use the factor in the 120 F column. Correction factors for liquid temperature Refrigerant 80 o F 90 o F 100 o F 110 o F 120 o F R R R-134a R-404A R Contact Danfoss for information on other refrigerants. In our example, the liquid temperature is 80 F. From the subcooling correction factor table, the correction factor for R22 at 80 F is.90, so F LT = This factor will be used below when the final capacity range for valve selection is calculated. Corrected evaporator capacity = Q 0 F LT = 2.0 Tr 0.90 = 1.80 Tr (R 22) Step 3 From the capacity table for the appropriate refrigerant, select the FIRST valve whose capacity for the appropriate evaporator temperature is greater than 1.80 tons at the pressure drop calculated in step 1. For our example, the pressure drop, p, is 6 psig, and from that column of the R22 capacity table, the correctly sized valve is KVQ 15, with a maximum capacity of 3.39 tons. Danfoss Inc. ( USCO / mks), USCO.PC.320.A1.22 5

6 Extended Capacity Table Ref. R-22 R-134a R-404a / R-507 R-407C Evap. temp. T o e F Capacity in tons KVQ KVQ Pressure drop across KVQ (psi) Pressure drop across KVQ (psi) USCO.PC.320.A1.22 Danfoss Inc. ( USCO / mks),

7 Design 1. Cover 2. Connection terminals 3. NTC resistor 4. Heating element 5. Pressure reservoir 6. Bellows 7. Bellows capsule 8. Pressure pin 9. Gasket 10. Threaded connection 11. Guide pin 12. Valve plate 13. Orifice 14. Damping device 15. Inlet 16. Outlet Danfoss Inc. ( USCO / mks), USCO.PC.320.A1.22 7

8 Dimensions and weight KVQ actuator KVQ valve Complete KVQ KVQ actuator Type H 1 B C NV D dia. 1 dia. 2 Weight in. in. in. in. in. in. in. lbs KVQ M KVQ M KVQ valve Connect. H2 H 3 B 1 C D D 1 NV Weight Type in. in. in. in. in. in. in. in. kg KVQ 15 5 / KVQ 22 7 / KVQ / KVQ / Complete KVQ Type H 4 H 5 Weight in. in. lbs KVQ KVQ USCO.PC.320.A1.22 Danfoss Inc. ( USCO / mks),

9 Danfoss Inc. ( USCO / mks), USCO.PC.320.A1.22 9

10 Danfoss Inc., Air-Conditioning & Refrigeration Division, 7941 Corporate Drive, Baltimore, MD Tel , Fax , 10 USCO.PC.320.A1.22 Danfoss Inc. ( USCO / mks),