TM 5-6640-212-14
CHAPTER 4
ORGANIZATIONAL MAINTENANCE INSTRUCTIONS
b. Replacement. Make sure replacement glass is of
4-1. Water Filters.
same diameter and length as original glass. Place the
a. There are two types of filters connected to the
two valve nuts on first with threads facing out to ends of
water tanks located in the front compartment of the
glass tube, install seal washers on both ends as shown
semitrailer petroleum laboratory. One is a dirt and rust
in figure 4-3. Install glass into upper valve seat as far as
filter and the other a taste and odor filter (2, fig. 2-3).
necessary for glass tube to clear bottom valve seat, then
CAUTION
carefully insert glass tube into bottom seat, adjust bottom
Do not overtighten pipe fitting, or use
seal washer, place teflon tape around treads of valve.
wicking or sealer. Teflon tape is
To obtain best seal, hand tighten bottom nut and repeat
recommended. Do not use torch near
above procedure for top seat, then tighten both nuts until
plastic. Do not use wrench to tighten
unit is free from any water leaks. Do not overtighten,
sump to head. This unit is designed
sight glass can break from stress due to overtightening.
to seal by hand tightening.
Open both valves to allow sight glass to fill. When full,
b. Cartridge Replacement. Original cartridge may
check for water leaks. If leak is noted, carefully tighten
have shorter than normal life due to disturbing pipes on
nut to stop leak. Turn on circuit breaker to water pump
installation. Replace cartridge when there is a decided
and check for leaks when system is under pressure.
drop in water flow at faucet or tap. To replace cartridge
4-3. Gas Analyzer.
proceed as follows:
a. Calibration.
(1) Close circuit breaker to water pump.
(1) Calibration consists of setting ZERO and GAIN
(2) Drop water level in water tank and depress
adjustments on the control module so that 0 to 100%
pressure relief button on top of filter head to relieve
Lower Explosive Limits (LEL) gas-air mixtures at the
pressure on filter.
detector drive the control module meter indicator
(3) Unscrew sump (fig. 4-1) from head of filter and
between 0 to 100% readings. Because each specific
remove used cartridge, taking care not to lose metal seal
combustible gas releases energy upon oxidation at a
plate located at bottom of cartridge.
different rate than another, different gases require
(4) Empty water and replace seal plate with
different calibrations.
After calibration has been
projection upward.
completed, control module WARN and ALARM
(5) Lubricate gasket (fig.
potentiometers may be adjusted to switch warning and
vasoline.
alarm relays in response to designated per cent LEL
(6) Place new cartridge on seal plate and screw
gas-air mixture levels at the detector. Then a RANGE
sump firmly onto head of filter but do not force. Sump
potentiometer is set to drive the meter indicator full-scale
must not be tight against flange of head. Do not use
when the TEST pushbutton is depressed, and a
wrench to tighten sump.
RECORD potentiometer may be adjusted to operate a
(7) Fill water tank and turn on circuit breaker for
recorder at desired voltage levels.
Calibration
water pump then depress pressure relief button until air
procedures are required for three different alarm system
is purged from filter. Release button and check water
applications:
flow at sink located in laboratory.
(a) Individual detectors.
4-2.
Water Tank Sight Glass Removal and
(b) Detectors paired with one control unit.
Replacement.
(c) One or two detectors per control unit sampling
a. Removal. Close both valves on top and below the
volatile hydrocarbons with flash points below 70 degrees
sight glass (5, fig. 2-3). Using a suitable wrench loosen
F.
nuts securing sight glass to upper and lower valves.
(d) Select and follow the procedure appropriate to
Carefully lift sight glass tubing up until bottom of sight
the existing system.
glass clears the bottom of the lower valve seat, and
remove sight glass. Refer to figure 4-3 and disassemble
sight glass assembly.
4-1
