Siemens SKP25 Series Electro-hydraulic actuators can be used in combination with any VG Series gas valve. The SKP25 gas actuators provide safety shut‐off control for industrial and commercial burner applications.
Safety Shut-off function:
Moreover the Siemens SKP25 electro‐hydraulic actuator consists of a cylinder filled with oil. In addition, it also consists of a piston containing an electric oscillating pump and a relief system. When power is supplied to the actuator, the relief system closes, and the pump moves oil from the reservoir into the pressure chamber. Therefore this action causes the piston to move downward in the cylinder, opening the gas valve. And when power to the actuator is interrupted, the relief system opens and the gas valve closes in less than 0.8 seconds.
A position indicator:
This is visible through the transparent window of the terminal box cover, shows the entire possible stroke range of the actuator. A light, which is visible through the lower left transparent window of the terminal box cover. In other words, this indicates when the actuator receives power. An optional, non‐ adjustable Single Pole, Double Throw (SPDT) proof of closure over travel switch signals the closed position after the gas valve has closed. An optional SPDT auxiliary switch is adjustable between 40% and 100% of the stroke. The adjustment screw and scale are located on the right side in the terminal box. These are visible through the transparent window of the terminal box cover.
The sealing gasket:
The AGA66 is between the actuator and the gas valve. This provides NEMA 3, 3R, and 4 protection rating for VGG10.xxxU / VGDxx.xxxU / VRD40.xxxU valves.
In addition, the SKP25.xxxUx controls the burner manifold gas pressure according to a fixed setpoint. In conclusion, the SKP25.xxxUx can also be applied as a 1:1 air/gas proportionator or zero governor.
AGA22 – yellow set point spring 6″ to 48″ w.c.
AGA23 – red set point spring 40″ to 100″ w.c.
AGA25.2 – damping orifice
AGA28 – black bias spring -0.4″ to 0.4″ w.c.
AGA29 – unpainted set point spring 0″ to 8.5″ w.c.
AGA66 – sealing gasket
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SIEMENS SKP25 SERIES:
US/Canada (UL Listed, FM Approved and CSA Certified only when assembled to series VG valves.)
SKP25.011U1 – 110 Vac, Safety Shut-off Actuator, Proof of Closure (POF) Switch
SKP25.012U1 – 110 Vac, Safety Shut-off Actuator, POF and Auxilliary Switches
SKP25.012U2– 220 Vac, Safety Shut-off Actuator, POF and Auxilliary Switches
SKP25.013U1 – 110 Vac, Safety Shut-off Actuator, no Switches
SKP25.411U1 – 110 Vac with POC Switch – High outlet pressure model for 1.5 to 20 psi outlet pressure regulation.
SKP25.611U1 – 110 Vac with POC Switch – High bias model for proportionator function with 0″ to -4″ w.c. bias.
The SKP20 has been replaced by SKP25 above.