WAC 296-36-155
Compressor plant. (1) Capacity. The
capacity, arrangement and number of compressors shall be
sufficient to maintain the necessary pressure without overloading
the equipment and to assure maintenance of such pressure in the
working chamber during periods of breakdown or other emergency. The compressor installation shall be capable of delivering not
less than 50 cubic feet per minute of ventilating air for each
man in the working chamber at the prevailing working chamber
pressure. Additional stand-by compressor units shall be
installed in accordance with the following tabulation:
Normal
installation
at 50
C.F./Man/Min.
units
Stand-by
units
Total
units
Percent
rated total
capacity of
stand-by
units
divided by
normal units
1
1
2
100
2
2
4
100
3
2
5
67
4
2
6
50
5
2
7
40
(2) Sources of power. Where the power is generated on the
job there shall be a sufficient number of power units to maintain
the necessary compressor operation.
(3) Power feeders. Where power is obtained from a public
utility there shall be at least two feeders to the compressor
plant. Each feeder shall have a capacity sufficient to carry the
entire load and normal overload. The feeders shall run over
separate routes in such a way that a breakdown of one feeder will
not cause any interruption of power from the other feeder. Each
feeder or service extension shall enter the compressor plant
through a separate and independent opening.
(4) Bus bar connections. There shall be duplicate feeder
bus bars at the compressor plant. Feeder connections to the bus
bar shall be such that either feeder can feed to each bus bar
separately or simultaneously to both bus bars. The electrical
connections from the bus bars to the compressor shall be arranged
in such a way as to insure continuous operation of the compressor
plant, in spite of any breakdown of an individual feeder, bus bar
or compressor unit.
(5) Alternate sources of power. Any combination of power
either generated at the job or generated off the job as set forth
above, and which complies with the above requirements is
permitted.
(6) Maintenance. All equipment including reserve sources of
power and reserve compressor equipment used to maintain pressure
in working areas shall at all times be maintained in good repair
and ready for use. All reserve equipment shall be periodically
inspected and shall be operated for a period of one hour or more
at least once in every week, except where there is danger of
sudden flooding, in which case reserve equipment shall be
operated at least one hour in every 24 hours. An ample supply of
spare parts shall be kept on hand.