ALLWEILER. Pressure-relief valves, indirectly pilot-controlled. Series DVI

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1 Pressure-relief valves, indirectly pilot-controlled Series DVI Range of application The pressure-relief valves of Series DVI can be applied for maximum operating temperatures up to 150 C (higher temperatures on request). The pressure-relief valves can be applied for mineral and synthetic hydraulic oils, lube oils and fuel oils. They are not to be used for corrosive, abrasive and contaminated fluids. The exact operating data of the pressure-relief valve such as pressures, maximum rate of flow and viscosity range can be taken from the data sheet. Types/Structural Design Together with the valve casing, the pressure-relief valve forms a control block. Structural design of the main control valve The valve casing (1) has a pressure-side connection (A) and a suction-side connection (B) or connection (T) to the tank. The valve cone (8) with nozzle (19) is guided in the valve seat bush (3). The O-rings (15) and (34) seal the spaces (A) and (L) off from space (B) or (T) in the valve casing (1). Sealing of the valve cone (8) with nozzle (19) is effected via the valve spring (30) through the valve seat (i) in the valve seat bush (3). Structural design of the pilot control unit The pilot control unit consists of the control bush (10), the control cone (11), the nozzle (57), the valve spring plates (6) and (7), the O-rings (16) and (20) and the valve spring (29). The control cone (11) is guided in the control bush (10) and, via the valve spring (29), pressed onto the valve seat (e), thus sealing it. The control casing (2) with screw plug (5) doses the hydraulic pilot control unit via the gasket (14) and the O-ring (20), sealing it off from the outside. By means of the adjusting screw (17) and the valve spring (29), the opening pressure is adjusted. The adjusting screw (17) is fixed in its position, checked by the hexagon nut (31). Mode of operation The fluid to be pumped enters space (A) of the valve casing (1), where it is under a specific operating pressure pressing against the valve cone (8). In pressurerelief valves without control liquid filter, the fluid to be pumped flows through the bore hole (H) in nozzle (19), transferring the operating pressure onto both the space (L) in the valve cone (8) and the control cone (11). As the guide diameter of the valve cone (8) is greater than the effective diameter of the valve seat (i), the valve cone (8) is kept closed hydraulically. In addition the valve spring (30), at zero pressure, presses the valve cone (8) in any mounting position onto the valve seat (i). The closing force of the valve spring (30) corresponds to the relief pressure. By means of the adjusting screw (17) the valve spring (29) is set to the required opening pressure, pressing the control cone (11) onto the valve seat (e). If the operating pressure increases above the set opening pressure, the control cone (11) overcomes the spring tension of the valve spring (29) and opens the valve seat (e). As a result, the space (L) in the valve cone (8) is connected with the space (B) or (T) via the valve seat (e) through the space (K), the bore hole (F). The fluid to be pumped which is in space (L) in the valve cone (8) commences to flow off through the space (B) or (T). As a result of the throttling effect of the bore hole (H) in the nozzle (19) or (104) as appropriate, the pressure in the space (L) of the valve cone (8) is reduced. The hydraulic closing force decreases so that the valve cone (8) is lifted off its valve seat (i). Now the fluid to be pumped commences to flow from space (A) into space (B) or (T). If the operating pressure falls below the set opening pressure, the control cone (11) doses the valve seat (e). No more fluid can escape from the space (L). In space (L) of the valve cone (8) the operating pressure is built up again as in space (A). The valve cone (8) is hydraulically kept closed. 1

2 Pressure-relief valves which are equipped with an additional valve spindle (52) and a spindle nut (50) serve for pressureless starting of the pump. It is moreover possible, during operation, to constantly branch off a certain delivery quantity from space (A) to space (B) or (T) with valve seat (i) open. Switching diagram according to DIN/ISO 1219 Operation Operation with adjusting screw By means of the adjusting screw (17), the respective opening pressure is adjusted. Clockwise rotation: Pressure build-up Counterclockwise rotation: Pressure reduction. Actuation of the hand relief system (HE) By opening the relief valve via the regulating screw (13), the pressure-relief valve can be depressurized by hand. For these purposes, turn regulating screw by 1 to 2 counterclockwise rotations. Thus, an almost pressureless circulation is possible, for example when starting the pump or during a short-time standstill of the plant. The relief valve being closed via the regulating screw, the pressure in space (L) increases. At the same time, the valve cone (8) closes and the system and/or opening pressure set at the adjusting screw (17) is built up again. For these purposes, turn regulating screw (13) clockwise against the stop. Operation with spindle nut (only size 38) With turning clockwise of the spindle nut (50), the valve spindle is pressed against the valve cone (8) lifting same from valve seat (i). Thus, a rated current can be carried off with the adjustment of the valve spring (29) not being changed. Actuation of the external control (FS) Instead of the screw plug (42), a piped 2/2 way solenoid valve can be connected to the control casing (2) for pressure relief. By actuating the solenoid valve, the pressure-relief valve can be released for pressure relief. Thus, an almost pressureless circulation is possible, for example when starting the pump or during a short-time standstill of the plant. 2

3 Abbreviation * max. flow with pipeline valves Characteristics Type of construction Cone seat valve Flow range [l/min] 10 to 3600 Fluids Lube, hydraulic, fuel oils, oil-in-water emulsions Temperature range [ C] -20 to +150 Viscosity range [mm 2 /s] 10 to 1000 Standard materials: Casing: Valve cone: O-rings: GG/GGG/GS/ST ST NBR/Viton 3

4 Types Type A Type B Type C Type D Type E Type F 4

5 Valve characteristic Increase of pressure depending on rate of flow Graphs refer to average values for viscosities of 10 to 150 mm 2 /s 5

6 Valve characteristic Increase of pressure depending on rate of flow Graphs refer to average values for viscosities of 10 to 150 mm 2 /s 6

7 Sectional drawing with parts list Pressure-relief valve Series DVI, type C (built-on, return to tank). (A) Space with inlet opening (F) Bore hole from space (K) to (T) (H) Bore hole in the nozzle (K) Space in control casing (L) Space in valve cone (T) Space with outlet opening (e) Valve seat (i) Valve seat Pressure relief by hand (HE) from size 44 Pressure relief by external control from size 44 Pressure relief by spindle nut Size 38 This sectional drawing only relates to a specific size and type of construction. Sectional drawings for further sizes and types of construction on request. Part No. Denomination Part No. Denomination Part No. Denomination 1 2 Valve casing Control casing Adjusting screw Nozzle Socket-head cap screw O-ring Valve seat bush Cover O-ring Joint ring Spindle nut Guide bush 6 7 Valve spring plate Valve spring plate Joint ring Spring dowel Valve spindle O-ring Valve cone Control bush Joint ring Valve spring Key Nozzle or grub screw Control cone O-ring Valve spring Hexagon nut Name plate Rivet 13 Regulating screw 33 Socket-head cap screw 14 1 Gasket 39 Screw plug 15 1 O-ring 42 Screw plug 1 Spare parts/replacement parts 16 1 O-ring 43 Socket-head cap screw 2 not represented 7

8 Valve dimensions and connections Type F, casing material GG/GGG/GS Design with DVI 44 Size Inlet- Flange Outlet- Flange Dimensions DN1 PN D1 K1 J1 d1 z1 b1 DN2 PN D2 K2 J2 d2 z2 b2 a1 a2 r l DVI44F R2" DVI47F DVI50F

9 Valve dimensions and connections Type F, casing material welded steel Size Inlet- Flange Outlet- Flange Dimensions DN1 PN D1 K1 J1 d1 z1 b1 DN2 PN D2 K2 J2 d2 z2 b2 a1 a2 r l h DVK4F R2" DVK7F DVI50F DVI56F

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12 Subject to technical alterations. The stated performance data are to be understood oniy as an outline of performance of our products. For exact limits of application please refer to the quotation and acceptance of oder. AG Postfach Radolfzell Allweilerstr Radolfzell Germany Tel. +49 (0) Fax (0) service@allweiler.de Internet: VM 774 GB/ Ident-Nr