The VG... gas valves with their electrohydraulic SKP... actuators are designed for gas families I, II, III and air. They are used primarily in gas-fired combustion plant. The valves open slowly and close rapidly. All types of VG... gas valves can be combined with the available types of actuators. The actuator is fitted to the valve body by means of the 4 screws contained in the terminal compartment. The square flange can be turned in steps of 90°, thus providing 4 different mounting positions. The actuator can be fitted or replaced while the valve is under pressure. Sealing materials are not required.
Actuator type SKP2... is equipped with an integrated precision gas pressure governor. This type of actuator with gas pressure governor not only reduces the length of the gas train, but usually also permits selection of a smaller valve size. For detailed information about valve sizing, refer to ?Flow chart?. The actuator is also available with limit and auxiliary changeover switches, e.g. for indicating the fully closed position or for stroke limitation in connection with 2-stage gas release, etc.
The SKP20.130... operates as a balanced gas pressure governor and controls the gas pressure according to the pressure of the combustion air so that the gas / air ratio remains constant over the entire load range (shifting the setpoint by the static pressure of the combustion air).
Therefore – in contrast to conventional gas / air ratio control – air volume changes due to mains pressure variations, soiled fan wheel, etc., have no impact on the quality of the combustion process.
Mechanical design
Actuator SKP2... with gas pressure governor
The gas pressure governor consists of
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working diaphragm
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safety diaphragm
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setpoint spring
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lever system for actuating a ball valve located in the bypass between the suction and pressure side of the hydraulic system.
The setpoint adjustment can be sealed.
The impulse pipe connection is Rp?.
The housings of actuator and governor are made of die-cast aluminium and the seals are made of elastomer.