MIL-DTL-68G
4.6.1.2 Hot. The insulation resistance of the fan shall be measured at the conclusion of the 4-hour operation
test (see 4.6.7) to determine compliance with 3.20.2.
4.6.2 Speed. The actual speed shall be determined by any convenient means to determine compliance
with 3.12 and 3.15.
4.6.3 Power input. The power input at full load shall be measured by any convenient means to determine
compliance with 3.8 and 3.11.
4.6.4 Dielectric strength. Following the examination and tests specified in 4.5 through 4.6.3, the fan shall be
subjected to an a.c. potential of 1000 volts for 1 minute applied between current carrying parts and the frame.
4.6.5 Effect of variations in power supply. All types except SD8-24, SD8-24NM, SD8-12, and SD8-12NM shall
operate satisfactorily between the limits of 105 and 125 volts.
4.6.6 Output. The thrust shall be measured in the following manner: the fan shall be suspended by two small
wires 150 inches long in the form of a swing with the upper ends of the wires at the ceiling, spread about 30 inches.
The fan shall fit into a cradle at the lower end, with the base of the fan about ½ inch from the floor and a sheet of
cross-section paper under the fan. The cross-sections shall be 1 inch square with 1/10-inch graduations allowing
readings to 1/10 inch. For long suspensions and small angles of deflection up to 5 degrees, the thrust shall be
calculated as follows:
defection, inches
Thrust in pounds =
times weight of fan, pounds
length of suspension, inches
Note Length of suspension shall be measured from the point of suspension to base of fan.
4.6.6.1 Methods other than that specified in 4.6.6, for making thrust measurements will be permissible, provided
calibration can be made so that thrust readings will agree with the procedure specified in 4.6.6.
4.6.7 Operation for 4 hours. Operation for 4 hours at rated voltage shall be conducted to ascertain satisfactory
operation of the following:
(a)
Bearings.
(b)
Input.
(c)
Speed.
(d)
Temperature rise.
(e)
Voltage.
(f)
Directional adjustment.
(g)
Speed control (two speed fans).
4.6.8
Airborne noise.
4.6.8.1 First article inspection. sound level measurements shall be made on the fans when operating at
full speed to determine compliance with 3.10.
4.6.8.1.1
Instrumentation. Measurements shall be made with a sound level meter conforming to type 2
of ANSI S1.4.
9
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business