action can be performed under all weather conditions and in an NBC environment. Under these
tactical conditions you must demonstrate your ability to properly purge the viewer infrared
The body of the AN/PAS-7A is filled with dry nitrogen and sealed to prevent dirt and
moisture from degrading the optical performance during use. The purge procedure was
developed so this dry nitrogen environment can be maintained throughout the useful life of this
device, and ensure good optical performance which the user must have to prevent personnel
injury or damage to equipment.
Before any attempt to purge any night vision device is made, there are some specific
actions you, the 39E maintainer should take:
Review all maintenance forms prior to doing any work.
Observe all safety precautions, with particular attention to all warnings and
cautions outlined in TMs .
Ensure all required special tools are available and in good working order.
Ensure purge station is assembled IAW TM 750-116.
Maintenance Request DA Form 2407 or 5504 and Equipment Inspection and
Maintenance Worksheet DA Form 2404 must be completed IAW TM 738-750 and local SOPs.
These documents provide critical information on non-mission-capable (NMC) time on-night
vision devices, as well as, capturing the man-hours you expend on the maintenance of these
When performing maintenance task on night vision devices, observe the special handling
requirements for nickel-cadmium batteries that contain sulphur dioxide gas under pressure.
There is an explosive danger with these types of batteries. The image intensifier tube in each
monocular contains toxic materials. If tube breaks guard against inhaling or swallowing
phosphor screen material. Ensure that nitrogen tank is secure to prevent personnel injury prior to
installing the purge kit. Prior to purging and filling any night vision device, an operational check
and troubleshooting procedure should be performed on the purge device IAW TM 11-5855-262-
24-1, Annex A, page A-2.