MIL-PRF-26139D
3.10.5.1 Pressure regulating valve. The pressure regulating valve shall be free from chatter and
of such capacity as to bypass the total output of the main blower at any pressure above 2 PSI
without creating more than 0.50 PSI pressure rise above the valve setting.
3.10.5.2 Valve control system. The valve control system shall be manually adjustable and will
remain fixed at any pressure set within the range of 2 through 12.5 PSI for all flow and
temperature conditions specified herein. The manual adjustment for the valve control system
shall be located on the instrument panel and calibrated in 0.25 PSI increments from 0 through
12.5 PSI (cabin pressure). The valve control system shall incorporate a sensitive means to adjust
flow and to correct for changes, and shall include a pilot control valve, air resistor, and
maximum pressure relief valve.
3.10.5.3 System dumping. A means shall be provided to dump the system at a minimum rate of
80 CFM with the unit running.
3.10.6 Air outlet connection. A 3 inch hose connection in accordance with SAE-AS5131 shall be
provided at the flowmeter discharge and shall extend 6 inches beyond the tester housing for hose
connection. The outlet shall be rigidly supported to prevent damage to the flowmeter in the event
the protruding section of the outlet is severely damaged, twisted, or sheared off. A protective
cap, attached in some manner, shall be provided to protect all air outlets.
3.10.7 Air ducts. The air ducts and passages between the components specified herein shall
provide a minimum of elbows, restrictions which would create an excessive pressure drop
through the system. Hose of proper temperature and pressure rating is allowed between blower
discharge and heat exchanger inlet.
3.11 Instrument control panel. The tester shall have a control panel on which all necessary
instruments, gages, switches, valves, and controls shall be mounted. The panel and its
accessories shall be readily accessible to operating personnel, and all items shall be so mounted
that they may be easily removed for replacement or servicing. Instruments subject to errors from
vibration shall be shock mounted. All items mounted on the panel shall be permanently and
legibly identified by nameplates. A 4 by 6 inch, engraved, permanent-type diagram plate,
showing the pneumatic circuit shall be securely fastened on or near the control panel. Voltages
greater than 110V shall not be used on the control panel. The panel shall be located at sufficient
height above the ground to accommodate a standing operator and inclined at an angle, 10°
minimum.
3.11.1. Flowmeter. The flowmeter shall be accurate to within at least 2 percent of scale and shall
measure the airflow to the aircraft being pressurized. The flowmeter shall provide a range of
from 10 through 400 CFM standard air at pressures from 2.0 through 14.0 PSI . The pressure
lines on the flowmeter shall be graduated in 2 PSI increments throughout the pressure range.
Protective covering shall be provided over the flowmeter to protect the operator from injury in
case the flowmeter should break or explode.
3.11.2 Temperature correction curve. A legible, waterproof, pressure, temperature correction
curve shall be provided and mounted on the panel adjacent to the flowmeter for correcting
8
For Parts Inquires submit RFQ to Parts Hangar, Inc.
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business