Page 28 - igem-g-4 edition 2

IGEM/G/4 Edition 2
live run
Verification of the correct operation of interlocks and the establishment of operating levels
with fuel available to a combustion space.

livesey seal
Attachment to the crown of some watersealed gasholders which isolates the inlet or outlet
main from any gas remaining in the gasholder.

load, relating to metering
Flow rate of gas required, which may be supplied in units of energy by a shipper or supplier to
a consumer and then converted into actual volume per hour, or corrected volume per hour.

load, relating to pipelines
Forces acting on a pipeline or other components.

locator (walkover system)
Electronic instrument used to determine the position and strength of electromagnetic signal
emitted from a transmitter sonde in the pilot head of a boring system, in an impact moling
tool or from existing underground services which have been energised.

lockout
Safety shut-down condition of a control system such that re-start cannot be accomplished
without manual intervention.

lockout – non-volatile
Safety shut-down condition of a control system, such that re-start can only be accomplished
by a manual re-set of the system and by no other means.

lockout – volatile
Safety shut-down condition of a control system, such that re-start can only be accomplished
by either a manual re-set of the system or an interruption of the main power and its
subsequent restoration.

lock-shut valve
Valve that, when closed, will not re-open unless a special tool and/or key is used.

lock-up
Complete closure of a regulator when gas demand falls to zero.

lock-up pressure
Outlet pressure at which a regulator locks up.

long range thermal stresses
Stresses induced from axial thermal expansion of a long straight pipeline from a uniform
temperature rise.

loss prevention
Systematic approach to preventing accidents or minimising their effects.

lowest operating pressure (LOP)
Minimum pressure which a system is designed to experience under normal operating
conditions.

low frequency (LF) transmitter
Device connected to a gas meter that provides electrical pulse outputs directly proportional to
the actual volume passed by a gas meter.

low level knock-off
Control which prevents gasholder (low pressure) discharge below a specified safe working
level.

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