3.2.5 Selection of Materials. - Specifications and standards for all
materials, parts, and Government certification and approval of processes and
equipment, which are not specifically designated herein and which are necessary
for the execution of this specification, shall be selected in accordance with
ANA Bulletin No. 143, except as provided in the following paragraph.
126.96.36.199 Standard Parts. - Standard parts (MS, AN, or JAN) shall be used
wherever they are suitable for the purpose, and shall be identified on the
drawing by their part numbers. Commercial utility parts such as screws, bolts,
nuts, cotter pins, etc., may be used, provided they possess suitable Properties
and are replaceable by the standard parts (MS, AN, or JAN) without alteration,
and provided the corresponding standard part numbers are referenced in the
parts list and, if practicable, on the contractor's drawings. In the event
there is not suitable corresponding standard part in effect on date of invitation
for bids, commercial parts may be used provided they conform to all requirements
of this specification.
3.3 Design and Construction.- The regulator shall be so designed and
constructed that no parts will work loose in service. It shall be built to
withstand the strains, jars, vibrations, and other conditions incident to
shipping, installation, and service.
3.3.1 The regulator shall be so constructed that adjustments and repairs
can easily be made by the personnel of operating units and overhaul bases
without the use of special tools.
3.3.2 The regulator shall be designed and constructed to reduce pressure
from an initial source at pressures up to 3750 psi to any delivery pressure
between 0 and 3500 psi, with a delivery rate of not less then 25 CFM of
air at any combination of inlet and outlet pressures within the design limits.
The pressure-adjustment control shall consist of a thread screw provided with
a suitable knob type handle which will require a maximum of 30 inch pounds of
torque to turn. The final delivery pressure shall not vary more than three
percent from the preset value.
3.3.3 Inlet Screen. - A suitable filter, equivalent to a 200 -mesh
screen, shall be provided in the inlet connection to prevent foreign particles
from entering the regulator, and shall be removable for inspection and cleaning
3.3.4 Pressure Gages.- The regulator shall be provided with two commercial-
type 2 1/2 inch pressure gages. One gage shall indicate inlet pressures from
0 to 4000 psi, and the other shall indicate delivery pressures from 0 to 4000
psi. The accuracy for each gage shall be within the commercial tolerances
established for this type of equipment, however, the tolerance shall not exceed
2 percent of the delivery pressure indicated.
3.3.5 Safety Valve. - A resealing-type safety valve shall be provided
in the delivery side of the regulator to prevent excessive build-up of pressure
in this chamber. The safety valve shall be preset and sealed to prevent
alteration of venting pressure. Venting shall begin at a delivery pressure in
excess of 3600 psi, and the safety valve shall reseal at a pressure of not
less than 3400 psi.