TM 5-4520-208-15
(4) Attach a 12-inch flexible air hose to
temperature indicated is within 10F
plus or minus of the thermometer
duct adapter at discharge end of heat-
in the air hose, temperature gage may
er. Make a small hole in the air hose
approximately two feet from the
be considered accurate at high end of
scale. If varation is greater than
adapter. Insert a thermometer in the
10F, note difference and take into
hole, with a sensing element of the
thermometer located at the center of
account when operating heater.
(10)
the air hose. Anchor the thermometer
After setting temperature selector
is this position.
valve to maintain the 280F. range,
set temperature selector indicator knob
(5) Loosen the setscrew on temperature
to the HIGH position with the pointer
indicator knob. Turn temperature se-
on the knob touching the pin. Tighten
lector knob clockwise as far as iii will
the setscrew to hold knob on shaft
go to close temperature selector valve.
(11)
Turn temperature selector valve knob
(6) Turn the temperature selector valve
counterclockwise to have temperature
knob counterclockwise three turns.
indicator knob pointer set at "l" on
Start the heater (para 32).
scale. After discharge air temperature
(7) When the reading on the discharge
appears to be stable, wait five minutes
temperature gage (fig. 11) appears
and read duct thermometer, A reading
stable, allow heater to run five more
of 150 10F. is desired.
minutes. Read thermometer in air
If reading is high, turn temperature
(12)
hose. A reading of 280 10F is
selector valve knob counterclockwise
desired.
until desired reading is obtained. This
( 8 ) If required temperature is not ob-
check is to determine if heater will
tained, turn temperature selector valve
operate at this low discharge temper-
knob one-quarter turn clockwise to in-
ature. If a lower temperature is ob-
crease temperature, or counterclock-
tained it is of little consequence.
wise to decrease. Wait five minutes
(13)
Check discharge temperature gage
after temperature stabilizes, read the
against temperature on air hose ther-
Repeat one-quarter
thermometer.
mometer as in step (9) above.
turns until desired range is obtained.
(14)
Recheck maximum temperature and
adj ust temperature selector valve in-
Note. The initial test setting of the tem-
dicator knob if necessary.
perature selector valve knob should be made
(15)
Stop the heater (para 34).
to maintain a lower temperature, so that
all subsequent adjustment will be made
(16)
Remove thermometer from hole in air
clockwise to prevent overheating.
hose and patch inside of air hose using
adhesive tape conforming to Specifica-
(9) When desired range is reached, check
tion PPP-T-60, Type III, Class I.
discharge temperature gage. If the
Section XVI. TIME TOTALIZING METER (BT400-40)
102. Time Totalizing Meter
101. General
a. General. The meter is mounted on a flange
The time totalizing meter is a direct-reading
which is part of the mounting bracket
indicator, driven by a belt (preformed packing)
b. Removal.
from the magneto pulley. Mounted above the
(1) Remove the power unit (para 12).
magneto, the time totalizing meter records the
(2) Remove magneto pulley and time
operating time of the heater in hours.
totalizing meter drive belt (para 82).
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