Siemens SKP55.011U1 is an Air & Gas Ratio Controlling Gas Valve Actuator with Safety Shutoff.

The compact Siemens SKP55 Pressure Regulating Actuators are designed for industrial and commercial burner applications.  In a combination of an SKP55 actuator and a single valve, the SKP55 can regulate or maintain constant pressure, safety shut-off function, and air/gas ratio control.  A gas valve with a small diameter can be utilized. 

Regardless of volume changes, the SKP55 actuator sustains the air to gas ratio in the gas supply line by controlling the pressure difference.  Having an upstream constant pressure regulator is not necessary when using the SKP55.  The SKP55 is applicable to any VG Series as long as the valve body is within 1/2"-6" in size.  Opening time is up to 14-seconds for maximum stroke and when power is interrupted it promptly closes <0.8 seconds.  At the transparent portion of the terminal cover, the actuator's stroke range is displayed, and a visible power-on indicator on the lower left side.

Note: VG Gas Valves are not included and must be ordered separately.