Page 42 - igem-g-4 edition 2

IGEM/G/4 Edition 2
security-type valve
Valve that cannot be closed or opened without the use of a special tool and/or key.

Se-duct system
Shared/common flue system where a duct rises vertically through a building. The duct is open
at the extremities to draw combustion air into, and take combustion products from, room
sealed appliances (Type C appliances).

sense, sensing (gas)
Refers to the gas pressure sensed at a point.

sensing line
Pipe through which pressure from a sensing point is transmitted to a device.

sensitive location
Location at which it may be difficult for people to escape or which has concentrations of people
who would have difficulty in escaping and/or with an increased sensitivity to thermal radiation.

sensor
Device that detects a change of physical parameter and generates an electrical signal
corresponding to that change, for example a photodiode which detects changes in light
intensity or a reed switch which responds to change in magnetic field.

service (pipe)
Pipe for conveying gas to premises from a distribution main, being any pipe between a
distribution main and the outlet of an emergency control valve (ECV).

service excess flow valve (SEFV)
Valve installed in a service which will substantially shut off the flow of gas in the event that the
flow exceeds a defined limit.

service isolation valve (SIV)
Valve (other than an emergency control valve (ECV)) for controlling the supply of gas, being a
valve:
 incorporated in a service (pipe)
 intended for use by a gas transporter (GT)
 not situated inside a building.

service pipework
Pipe for distributing gas, for example liquefied petroleum gas (LPG), to premises from a
storage vessel to the outlet of an ECV.

service regulator
Apparatus for automatic regulation of pressure or of volume flow at a selected point within a
service (pipe).

set point
Value of pressure or flow rate which a regulator or other control device is set to maintain.

set pressure
Command value to a pressure regulating system.

shakedown
Condition of elastic system response once initial localised yielding has occurred under the
limits of coincident pressure and temperature.

shared/common flue system
Flue system serving two or more appliances.

38
©IGEM, IGEM House, High Street, Kegworth, Derbyshire, DE74 2DA. Website: www.igem.org.uk