Condensing pressure regulator, type KVR Differential pressure valve, type NRD

Transcription

1 MAKING MODERN LIVING POSSIBLE Data sheet Condensing pressure regulator, type KVR Differential pressure valve, type NRD The condensing pressure regulator, type KVR can be mounted in either the gas or liquid side of the condenser in refrigeration and air conditioning systems. They are used to maintain a constant and sufficiently high condensing pressure with systems using air-cooled condensers. They can also be used with valve types NRD or KVD to assure that adequate pressure is maintained on the receiver. Features y Accurate, adjustable pressure regulation y Wide capacity and operating range y Pulsation damping design y Stainless steel bellows y Compact angle design for easy installation in any position y Hermetic brazed construction y ¼ in. Schrader valve for pressure gauge connection y Available with flare or ODF solder connections y Can be used as a relief valve from high pressure to suction side y KVR 12-22: Compliant with ATEX hazard zone 2 y NRD: for use with HCFC, HFC and HC refrigerants Approvals UL LISTED, file SA7200 GOST AN30 DKRCC.PD.HC0.B3.22 / 20H8762

2 Technical data 1 psi = 0.07 bar / 9 (t 1 F -32) = t 2 C HCFC, HFC and HC: KVR Refrigerants HCFC and non-flammable HFC: KVR 28-3 Pe = psig Regulation range Factory setting = 14 psig KVR: PS/MWP = 406 psig Maximum working pressure NRD: PS/MWP = 667 psig KVR: Pe = 40 psig Maximum test pressure NRD: Pe = 870 psig Medium temperature range KVR: F KVR 12 22: 90 psi P band (full valve stroke) KVR 28 3: 72. psi Start opening: Δp= 20 psi Opening differential pressure for NRD Fully open: Δp = 43 psi Ordering KVR 12, KVR 1, KVR 22, KVR 28, KVR 3, NRD Type Rated liquid capacity 1) [TR] Rated hot gas 1) [TR] Flare connection 2) Code no. Solder connection Code no. R22 R134a R404A/ R07 R407C R22 R134a R404A/ R07 R407C [in.] [in.] KVR / 2 034L / 2 034L0093 KVR / 8 034L0092 / 8 034L0097 KVR / 8 034L0094 KVR / 8 034L009 KVR / 8 034L0100 NRD 1 / ) Rated capacity is based on: evaporating temperature t e = 40 F condensing temperature t c = 110 F pressure drop across the valve p = 3 psi for liquid capacity p = 6 psi for hot gas capacity 2) KVR are delivered without flare nuts. Separate flare nuts can be supplied: 1 / 2 in. code no. 011L1103 / 8 in. code no. 011L1167 The connection dimensions chosen must not be too small, as gas velocities in excess of 130 ft/s at the inlet of the regulator can result in flow noise. 2 DKRCC.PD.HC0.B3.22 / 20H8762

3 Liquid capacity Max. regulator capacity Q e 1) Type Condensing temperature t c Liquid capacity [TR] Offset 4 psi Hot gas capacity [TR] Offset 4 psi Pressure drop p [psi] Pressure drop p [psi] [ F] R22 KVR 12 KVR 1 KVR 22 R KVR 28 KVR R134a KVR 12 KVR 1 KVR 22 R134a psi = 0.07 bar / 9 (t 1 F -32) = t 2 C 1 TR = 3. kw 1 in. = 2.4 mm KVR 28 KVR ) The capacities are based on: Evaporating temperature t e = 40 F. For other evaporating temperatures see table below. Correction factors (evaporating temperature) t e [ F] R R134a System capacity x correction factor = table capacity. DKRCC.PD.HC0.B3.22 / 20H8762 3

4 Liquid capacity (continued) Maximum regulator capacity Q e 1) Type Condensing temperature t c Liquid capacity [TR] Offset 4 psi Hot gas capacity [TR] Offset 4 psi Pressure drop p [psi] Pressure drop p [psi] [ F] R404A/R07 R404A/R KVR 12 KVR 1 KVR KVR 28 KVR R407C KVR 12 KVR 1 KVR 22 R407C psi = 0.07 bar / 9 (t 1 F -32) = t 2 C 1 TR = 3. kw 1 in. = 2.4 mm KVR 28 KVR ) The capacities are based on: Evaporating temperature t e = 40 F. For other evaporating temperatures see table below. Correction factors (evaporating temperature) t e [ F] R404A/R R407C System capacity x correction factor = table capacity. 4 DKRCC.PD.HC0.B3.22 / 20H8762

5 Sizing Valve selection For optimum performance, it is important to select a KVR valve according to system conditions and application. Example When selecting the appropriate valve it may be necessary to convert the actual evaporator capacity using a correction factors. This is required when your system conditions are different than the table conditions. The selection is also dependant on the acceptable pressure drop across the valve. The following example illustrates how this is done. The following data must be used when sizing a KVR valve: y Refrigerant: HCFC, HFC and HC:KVR 12-22, HCFC and non-flammable HFC: KVR 28-3 y Evaporator capacity Q e in [TR] y Evaporating temperature t e in [ F] y Condensing temperature t c in [ F] y Connection type: flare or solder y Connection size in [in.] KVR in a liquid capacity application y Refrigerant: R22 y Evaporator capacity: Q e = 28.7 TR y Evaporating temperature: t e = -40 F ~ 21 psig y Condensing temperature: t c = 90 F ~ 170 psig y Connection type: Solder y Connection size: / 8 in. Application example Liquid capacity application Hot gas capacity application DKRCC.PD.HC0.B3.22 / 20H8762

6 Valve selection (continued) Step 1 Determine the correction factor for evaporating temperature t e. Correction factors (evaporating temperature) From the correction factors table an evaporating temperature of -40 F, R22 corresponds to a factor of t e [ F] R R134a R404A/R R407C Step 2 Corrected evaporator capacity is Q e = 28.7 x 1.12 = TR Step 3 Now select the appropriate capacity table and choose the line for a condensing temperature t c = 90 F. Using the corrected evaporator capacity, select a valve that provides an equivalent or greater capacity at an acceptable pressure drop. KVR 12, KVR 1, KVR 22 delivers 38.2 TR at a 2 psi pressure drop across the valve. Based on the required connection size of / 8 in. ODF, the KVR 1 is the proper selection for this example. Step 4 KVR 1, / 8 in. solder connection: code no. 034L DKRCC.PD.HC0.B3.22 / 20H8762

7 Design / Function KVR NRD Danfoss 34L KVR 1. Seal cap 2. Gasket 3. Setting screw 4. Main spring. Valve body 6. Equalizing bellows 7. Valve plate 8. Valve seat 9. Damping device 10. Manometer connection 11. Cap 12. Gasket 13. Insert NRD 1. Piston 2. Valve plate 3. Piston guide 4. Valve body. Spring Danfoss 34L The condensing pressure regulator, type KVR opens upon a rise in pressure on the inlet side, i.e. when the pressure in the condenser reaches the set value. KVR regulates on the inlet pressure only. Pressure variations on the outlet side of the regulator do not affect the degree of opening, as the valve is equipped with equalization bellows (6). The bellows has an effective area corresponding to that of the valve seat neutralizing any changes to the setting. The valve is also equipped with a damping device (9) providing protection against pulsations which can normally arise in a refrigeration system. The damping device helps to ensure long life for the regulator without impairing regulation accuracy. Differential valve type NRD begins to open when the pressure drop in the valve is 20 psig, and is fully open when the pressure drop is 43 psig. DKRCC.PD.HC0.B3.22 / 20H8762 7

8 P-band and Offset Principle diagram Capacity Setting [psi] Offset 1 psi = 0.07 bar / 9 (t 1 F -32) = t 2 C P-band Proportional band The proportional band or P-band is defined as the amount of pressure required to move the valve plate from closed to full open position. Example: If the valve is set to open at 120 psig and the valve P-band is 90 psi, the valve will give maximum capacity when the inlet pressure reaches 210 psig. Offset The offset is defined as the permissible pressure variation in condenser pressure (temperature). It is calculated as the difference between the required working pressure and the minimum allowable pressure. The offset is always a part of the P-band. Example with R22: A working temperature of 110 F ~ 230 psig is required, and the temperature must not drop below 100 C ~ 200 psig (set point). The offset will then be 30 psi. 8 DKRCC.PD.HC0.B3.22 / 20H8762

9 Dimensions [mm] and weights [kg] KVR NRD KVR, NRD Type Connection Flare Solder ODF NV 1 NV 2 H 1 H 2 H 3 L L 1 B 1 B 2 C Solder ød Net weight KVR 12 1 / 2 1 / KVR 1 / 8 / KVR 22 7 / KVR / in. = 2.4 mm 1 lb = 0.44 kg KVR / NRD 1 / DKRCC.PD.HC0.B3.22 / 20H8762 9