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.