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|  MIL-C- 18419 B(SHIPS)
designed to withstand the maximum operating pres-
3.3.22.2 Gage_ piping, - Gage piping shall be in
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sure of the final stage. The sight flow indicators
accordance with Drawing 810-1385850, except that
and the manual bypass valves shall be located at the
flared tubing fittings and tapered pipe threads will
designated operating side of the compressor in such
not be permitted, and except that root valves are
a manner as to be readily observed and manipulated
not required for any gage line connected to a sys-
by the operator. The mounting arrangement of these
tem which will be automatically depressuriz ed when
items shrill also be such that they can be readily re-
the compressor stops. Gage cocks may have test
located on the opposite side of the compressor to
plugs in the valve body or stem in lieu of separate
provide right or left hand installation (see 3.3. 7).
test plug fittings.
3.3.20.4 The condensate accumulator shall be
3.3.22.3 Temperature instrument. - A temper-
connected to a separate gage on the gage board.
ature indicating and alarm instrument similar to
This gage shall hav e a maximum scale reading no
that specified in MIL-T-15377 shall be provided on
higher than the maximum operating pressure (or the
each air compressor, A selector switch shall be
provided to read at least twelve temperatures, and
next available scale reading above) so significant
pressure indicating can be obtained at the lowest
suitable circuits to automatically shutdown the com-
stage pressure.
pressor in the event any one of the selected temper-
ature sensitive points (as many as five may be se-
3.3.20.5 The quantity of air lost as the result of
lected) exceeds a predetermined amount. The
shutdown temperatures shall be individually adjust-
opcration of the automatic drain system shall be
kept to a minimum, and shall not exceed 3 percent
able over a range of 200 F. to 500 F. An alarm
of the rated capacity of the compressor. This shall
indicating light shall be mounted on the face of the
instrument which will operate in conjunction with
not reduce the required output of the compressors as
the shutdown feature. The Instrument shall be lo-
required by 1.2.
cated with its instrument panel readily accessible
on the operating side of the compressor, and its
3.3.20.6 The Bureau of Ships will give consid-
mounting arrangement shall be such that it can be
eration to an automatic condensate drainage system
readily relocated to the opposite side of the com-
differing from that described in 3. 3.20.2 to 3.3.20.4
pressor to provide for right or left hand operation,
inclusive, provided it is demonstrated by actual test
that the same end result is accomplished. The test
3.3.22.3.1 Temperature sensing elements shall
shall be witnessed by a representative of the Bureau
be provided to detect the inlet and outlet tempera-
of Ships prior to class C drawing approval of the
system.
tures at each stage of compression, the final air
discharge temperature, the lubricating oil temper -
ature in the reservoir, the cooling water outlet
3.3.21 Unloading. - Each compressor shall be
temperature, and the temperature at any other
fitted with automatic unloading devices. These de-
points considered by the manufacturer to be critical.
vices shall discharge residual air pressure to
atmosphere immediately after the compressor is
3.3.22.3, 2 The sensing elements shall be in-
stopped, so that the compressor will always be un -
serted directly into the air, water or oil without the
loaded when starting.
use of separate wells. Elements inserted in ar
streams shall be capable of withstanding 5, 000
3.3.22 Fittings. -
p.s. i.g. pressure. Elements inserted in water
shall be corrosion resistant. The lead wires from
3. 3.22. 1 Pressure gages. - All pressure gages
the sensing elements to the indicating and alarm
shall be 3 1/2 inch dial size safety type gages in ac-
instrument case shall be two copper wires incased
cordance with MI L-G-18997, and shall be mounted
in suitable Navy type cable. Lead wires shall be
on a common gage board. The gage board and its
readily disconnected from the sensing elements
mounting brackets shall be designed so that the
without removal of the element from the compres-
board may be relocated from one side of the com-
sor, and may be grouped into a harness or bank for
pressor to the opposite side, or to a bulkhead. The
entry into the instrument case through a multiple,
brackets shall be readily removable from the board,
bayonet type connector.
3.3.22.1.1 Pressure gages shall be provided to
indicate the air-d elivery pressure from each stage
3.3.22.4 Final check valve. - The final air dis-
charge shall be provided with a check valve which
of Compression, the pressure in the condensate ac-
shall be sufficiently tight to permit unloading and
cumulator, the pressure in the circulating water
dcpressurizing of the compressor at shutdown.
system, and the lubricating oil pressure. All gages
on the gage board shall be suitably identified by the
3.3.22.5 Small manually operated valves such
adjacent attachment of identification plates on the
as gage cocks, separator drain valves, and simi-
gage board. Each gage shall be provided with
lar items shall be of the soft seat type or tapered
means to indicate the normal desired working pres-
needle type with replaceable packing. Such valves
sure, and such working pressures shall be indicated
on drawings and in manuals,
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