Differential pressure control AVP/AVP-F

Transcription

1 Application AVP is a self-acting differential pressure control that closes on rising differential pressure. AVP is primarily used in block and district heating systems. The control has external threads for heating system connection. Weld-on tailpieces and tailpieces with external threads are available as accessories. The control is supplied complete with compression fittings for connecting Ø6 mm copper impulse tube. Differential pressure control AVP-F with a fixed differential pressure of 0.2 or 0.3 bar are available on request. Principle Fig. 1 Direct-connected heating system Fig. 2 Indirectly connected heating system SIBC R&D VD.55.L4.02 Danfoss 6/98 1

2 Ordering Complete control with compression fittings for impulse tube connection Setting range: bar Setting range: bar External Typ DN thread 1) k v Code No. 2) k v Code No. ISO 228/1 m 3 /h m 3 /h AVP G ¾ A H H2021 AVP G ¾ A H H2022 AVP G 1 A H H2023 AVP G 1¼ A H H2024 AVP G 1½ A H H2025 1) X P = 0.15 bar 2) X P = 0.10 bar 1 set of accessories including 2 tailpieces, 2 union nuts and 2 seals Weld-on tailpieces Tailpieces with external threads DN Code No. Code No N N N N N N N N5073 Spare parts Spare parts Code No. 10 compression fittings for impulse tube 003H2300 Adjustment section bar and diaphragm 003H2301 Adjustment section bar and diaphragm 003H2302 Valve insert, k vs = 1.6 m 3 /h 003H2310 Valve insert, k vs = 2.5 m 3 /h 003H2311 Valve insert, k vs = 4.0 m 3 /h 003H2312 Valve insert, k vs = 6.3 m 3 /h 003H2313 Valve insert, k vs = 10.0 m 3 /h 003H2314 Design 1. Valve body 2. Type label 3. Valve insert 4. Spindle 5. Pressure relief cylinder 6. Union nut 7. Control diaphragm 8. Compression fittings for impulse tube 9. Diaphragm section 10. Setting spring 11. Handle 2 VD.55.L4.02 Danfoss 6/98 SIBC R&D

3 Materials, parts in contact with water Valve body:... RG 5, DIN 1705, W.no Valve insert:... Dezincing-free brass,... BS 2874 Valve cone:... Dezincing-free brass,... BS 2874 Valve plate:... EPDM Valve seat:... CrNi steel, DIN 17440, W.Nr Pressure reliefcylinder:... CrNi steel, DIN 17440, W.Nr O-rings:... EPDM Springs:... CrNi steel, DIN 17224, W.Nr Diaphragm body:zinc chromatic steel,... DIN 1624, W. Nr Diaphragm:... EPDM Data Pressure stage PN 16 Max. differential pressure 12 bar Max. water temperature 140 C Cavitation factor z 0,6 1) Water for district heating and central heating Medium systems, according to VDI Glyconic water resistant down to 30 C Medium ph Min. 7, Max. 10 1) k v k vs 0, 5inDN25andDN32 versions Adjustment Relation between scale figures and differential pressure. Values given are approximate Fitting The control must be mounted in the heating system return. The positive wire must be fitted in the mixing circuit flow of direct-connected heating systems (fig. 1) and in indirecly connected systems (fig. 2) ahead of the control valve in the direction of flow. The negative wire is integrated in the valve. The control can be fitted in any position. Further fitting details are described in the instruction accompanying the product. SIBC R&D VD.55.L4.02 Danfoss 6/98 3

4 Sizing Example 1 Motor valve for mixing circuit in directconnected heating systems requires differential pressure of 0.1 bar (fig. 1 and 3) Given: Q max p min p circuit p motor valve p AVP p AVP = 350 l/h (0.35 m 3 /h) = 0.7 bar (70 kpa) = 0.1 bar (10 kpa) = 0.1 bar (10 kpa) = p min p motor valve = = 0.6 bar (60 kpa) Possible pipe pressure losses are not included. k v value is calculated according to formula: Qmax 035. k v = = =. m / h pavp or read from sizing diagram by taking a line through Q-scale (0.35 m 3 /h) and p v scale (0.6 bar) to intersect k v -axis at 0.5 m 3 /h. Solution: The example selects AVP 15 with setting range bar, X p = 0.02 bar, k v = 1.6. At 0.1 bar control setting AVP varies from 0.1 bar at open valve and = 0.12 bar at closed valve. Q max p min p Circuit p avp p Motor valve Example 2 Motor valve for indirectly connected heating systems requires differential pressure of 0.5 bar (50 kpa) (fig. 2 and 4) Given: Q max = 1.25 m 3 /h p min = 1.0 bar (100 kpa) p exchanger = 0.05 bar (5 kpa) p motor valve = 0.5 bar (50 kpa) p AVP = p min p exchanger p motor valve p AVP = = 0.45 bar (45 kpa) k v value is calculated according to formula: Qmax 125. k v = = =. m / h pavp or read from sizing diagram by taking a line through Q-scale (1.25 m 3 /h) and p v scale (0.45 bar) to intersect k v axis at 1.9 m 3 /h. Solution: The example selects AVP 15 with setting range bar, X p = 0.07 bar, k v = 2.5. At 0.5 bar control setting AVP varies between 0.5 bar at open valve and = 0.57 bar at closed valve. Possible pipe pressure losses are not included. Q max p min p Exchanger p avp p Motor valve 4 VD.55.L4.02 Danfoss 6/98 SIBC R&D

5 Sizing Select suitable control size and P-band (X p ) not exceeding 50% of the set control differential pressure. SIBC R&D VD.55.L4.02 Danfoss 6/98 5

6 Dimensions H L 1 L 2 L 3 mm mm mm mm ISO 228/1 DN G ¾ A DN G 1 A DN G 1¼ A DN G 1½ A Nipple for impulse tube 6 VD.55.L4.02 Danfoss 6/98 SIBC R&D