Thermostatic element RAVV for 2-way valves

Transcription

1 Description / Application RAVV is a self-acting thermostatic element which can be combined with 2-way valve bodies RAV-/8, VMT-/8 or VMA 15. RAVV is used to control temperatures in small hot water cylinders and to control flow temperatures in central heating systems. There is a special version with a section of the capillary tube coiled up to function as minimum temperature sensor. This version can be used to control air heating coils. RAVV-RAV and RAVV-VMT - closes on rising sensor temperature - must be installed in the flow pipe - is dimensioned for pressure stage (PN) 10, max.120 C RAVV-VMA - closes on rising sensor temperature - must be installed in the flow pipe - is dimensioned for pressure stage (PN) 16, max.130 C Principles Hot water cylinder Air heating coil Ordering Setting Capillary tube Max. Type range lenght sensor temperature Code No. C m C U1255 1) RAVV ) U U1252 1) U1251 1) 1) Incl. R 1 p / 2 capillary tube gland 2) Effektive lenght including minimum temperature sensor Accessories Material Code No. Brass 993N3568 Sensor pocket Stainless steel 993N3615 SIBC VD.52.O2.02 Danfoss 05/02 1

2 Valve bodies Type Connection 1) k v Inlet Outlet m 3 /h Code No. RAV 10/8 R 3 p /8 3) R 3 /8 3) U0012 RAV 15/8 R 1 p / 3) 2 R 1 / 3) U0017 RAV 20/8 R 3 p / 3) 4 R 3 / 3) U0022 RAV 25/8 R p 1 3) R 1 3) U0027 VMT 15/8 2) G 3 / 4 A 4) G 3 / 4 A 4) F0115 VMT 20/8 2) G 1 A 4) G 1 A 4) F0120 VMT 25/8 2) G 1 1 / 4 A 4) G 1 1 / 4 A 4) F0125 VMA F2031 VMA F2032 VMA 15 G 3 / 4 A 4) G 3 / 4 A 4) F2033 VMA F2034 VMA F2035 1) The capacity (k v ) iapplies to a P-band of 6 C. Other P-band, see "Data". 2) Ordering cooper fittings, see "Accessories" 3) According to ISO 7/1 4) According to ISO 228/1 Accessories VMT Type Copper fittings (delivered in boxes of 10) Code No G4125 VMT G G4128 VMT U U0135 VMT U0140 Accessories VMA Typ Nipple sets Code No. VMA 15 Set of weld-on nipples 003N5090 VMA 15 Set of nipples with external threads 003N5070 Data k v (m 3 /h) Max. Max. Max. Max. Type for a P-band in C of working differential test flow pressure pressure pressure temperature RAVV bar bar bar C RAV 10/ RAV or VMT 15/ RAV or VMT 20/ RAV or VMT 25/ VMA 15 (k vs = 0.4) ) VMA 15 (k vs = 0.63) VMA 15 (k vs = 1.0) ) VMA 15 (k vs = 1.6) VMA 15 (k vs = 2.5) ) 1) In installations requiring a low-noise function the differential pressure is not to exceed 1 bar. 2 VD.52.O2.02 Danfoss 05/02 SIBC

3 Design Materials, parts in contact with water Valve body: Ms 58, nickel plated Valve cone: NBR-rubber Pressure pin: Stainless steel 18/8 O-ring: EPDM-rubber Sensor: Cu, nickel plated Sensor pocket: Brass or stainless steel 1. Setting knob 2. Setting spring 3. Bellows element 4. Gland 5. Bottom screw 6. Valve body 7. Valve cone 8. Remote sensor 9. Capillary tube gland Setting Relation between scale figures and closing temperature. The values given are approximate. Installation The valve body must be fitted in the flow pipe with the flow in direction of the cast-in arrow. The flow temperature must be min. 15 C higher than the set closing temperature. The sensor must be fitted in position from horizontal to vercally down. The sensor must always be placed in a pocket when the temperature is to be measured directly in a medium. SIBC VD.52.O2.02 Danfoss 05/02 3

4 Sizing Example: Temperature control for hot water service Given Load: Cooling (flow - return): 20 C 14 kw (12000 kcal/h) Flow volume: = 0.6 m 3 /h Differential pressure p across the valve: 0.12 bar Required Correct valve size Method From the flow volume (0.6 m 3 /h) and the differential pressure (0.12 bar) read off the necessary k v -value in the diagram = In this example, a P-band of 6 C is required. From the k v -columns in the table, under 6 C, find the appropriate valve body. Here, the most suitable valve body is RAV 25/8 or VMT 25/8 with a k v -value of VD.52.O2.02 Danfoss 05/02 SIBC

5 Dimensions RAVV-RAV/8 RAVV-RAV/8 d d Widths 2 across flats L L 2 L 3 L 4 L 5 H 1 H 2 S 1 S 2 DN ISO 7/1 mm mm mm mm mm mm mm mm mm 10 R 3 p /8 R 3 / R 1 p / 2 R 1 / R 3 p / 4 R 3 / R p 1 R RAVV-VMT 15/8 Widths a b L 1 L 2 H 1 across flats DN mm ISO 228/1 mm mm mm S mm 15 15/ 16/ 18 G 3 / 4 A / 22 G 1 A G 1 1 / 4 A RAVV-VMT RAVV-VMA a L L 1 L 2 S DN ISO 228/1 mm mm mm mm 15 G 3 / 4 A RAVV-VMA Pocket sensor SIBC VD.52.O2.02 Danfoss 05/02 5

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