Page 38 - igem-g-4 edition 2_Neat

IGEM/G/4 Edition 2
promoter
Persons, firm, company or authority for whom a new service or other work is being carried out
(includes “contractor”).

proof of closure (POC) switch
Switch fitted to a safety shut-off valve (SSOV) with mechanical over-travel, which proves the
SSOV to be in the fully closed position.

proof stress (R)
For materials which do not exhibit a sudden clear yield point, stress at which a non-
proportional elongation, equal to a specified percentage of the original gauge length, occurs.

protected shaft
Shaft that passes directly from one compartment to another, enclosed within a fire resistant
construction.

protective device or system
Device that limits the amount of energy passing into a hazardous area from a non-hazardous
(safe) area.

protective multiple earth (PME)
Earthing arrangement, found in TN-C-S systems, in which the supply neutral conductor is used
to connect to the earthing conductor of an installation with earth.

proving
Sensing of a system parameter, for example a gas pressure, a valve position or shaft speed
which, either directly or indirectly, ascertains unambiguously that it is within a prescribed
range.

proximity distance
Minimum distance permissible between a pipeline or installation and any normally-occupied
building or traffic route.

public highway
Way over which all members of the public have a right to pass and re-pass provided that the
use of the way is of right and not by permission.

pull-back
That part of a guided boring or directional drilling process in which the drill string is pulled
back through the bore into the entry pit, usually installing the product pipe at the same time.

pulsation vessel
Vessel provided for damping out flow and pressure pulsations produced by a gas compressor.

pup
Short make-up piece of pipe.

purge velocity
Velocity of purge gas in a vent pipe.

purge/purging
Displacement of one type of gas/fluid with another gas/fluid.

purge end-point
Pre-specified mixture of components, chosen so that hazardous mixtures cannot be formed at
any stage of the purging operation.

purge pressure
Pressure in a pipe during purging.

34
©IGEM, IGEM House, High Street, Kegworth, Derbyshire, DE74 2DA. Website: www.igem.org.uk