The Powerseat family is an electro-hydraulically operated range of gas safety shut-off valves with ultra high flow rates and a range of associated accessories. Their primary function is the on-off control of low pressure combustible gases, air and oil and may be used for both control and safety shutoff purposes. The valves are suitable for the three families of combustible gas as follows, 1st, town gas; 2nd, natural gas and 3rd, Liquefied Petroleum Gases. They are suitable for oil with a viscosity of up to 200 seconds Redwood. The valves are normally closed, i.e. energise to open, and are operated from a.c. mains at 230 or 110 volts. Electrohydraulic operation ensures a smooth, controlled opening at low speed whilst closure time is less than 1 sec. Powerseats are available in connection sizes from 1½” (DN40) to 3” (DN80) screwed, and from DN65 (2½”) to DN250 (10”) Flanged, thereby covering an extremely wide range of commercial and industrial applications. Complementary high quality solenoid valves are available to cover smaller sizes, where the ultra high flow rate of the Powerseat is not so important Valve construction consists of a die cast aluminium body, a removable stainless steel strainer and an actuator having the valve closure head as an integral part. The actuator may be removed from the body for servicing and access to the strainer without removal of the body from the line. The actuator consists of a pump and motor, a relief valve, operating cylinder, piston and push rod, valve head and seals, hydraulic fluid and electrical switchgear. When the valve is energised the relief valve closes, the motor starts and the pump forces fluid into the cylinder driving the valve open. At this point the closed position switch contacts change state (this does not affect the operation of the valve as they would typically be connected to an external burner sequence control). When the fully open position is reached a limit switch (adjustable) changes state, switches off the pump motor and illuminates an amber neon indicator on the case to show that the valve is fully open. Where a factory fitted optional open position switch is fitted this will also change state, again without affecting the valve operation as it will be connected to an external control system. The relief valve remains closed and will do so until power is removed. Removal of power causes the relief valve to open and the safety shut off valve to close. Manual reset switches, either integral or remote mounting, are available as accessories for on site fitting. When wired in, manual intervention is required to operate the valve after mains interruption, i.e. after a power cut or when the valve is first energised. To facilitate this, the ‘reset button’ is momentarily depressed latching the reset switch in the ‘on’ position allowing the valve to operate. Additional features of the 200 and 250mm Powerseat These valves feature a membrane covered control panel on the actuator. Upon energising the valve a red LED illuminates on the control panel and remains illuminated whilst power is ‘on’ to the valve. Whilst the pump is running an amber LED on the control panel flashes to indicate that the valve is opening. This goes out when the valve is fully open and is replaced with a green ‘open’ LED. The valves feature an integral ‘manual reset switch’ as standard which can be wired out at any time. Operation of the switch is otherwise identical to the optional switches on the smaller valves.