Det-Tronics PW9200x Pathwatch IR Gas Detection System - Manual (Page 12)

WARNING
If both conduit entrances to the junction box are
not used, the unused entrance must be fitted
with an explosion-proof pipe plug with at least
five full threads engaged.
4. Connect HYDROCARBON ALARM relay and STA-
TUS ALARM relay signal terminals (4, 5, 6 and 7)
to external readout devices (e.g., indicator lamps,
alarm buzzers, motors, computer interface, etc.).
The hydrocarbon alarm relay contacts open when
a preset concentration of hydrocarbon vapor is
exceeded. The status alarm relay contacts open
when an obstruction or instrument failure is
detected.
5. Connect transmitter and receiver to the power
source. DO NOT apply power.
6. Be sure that the cover bolts are tight. Check
tightness of junction boxes and window assem-
blies.
7. Remove protective window covers from both the
transmitter and the receiver. Do not discard.
8. As power is first applied to the instrument, the
transmitter lamp should light and a faint rotation
noise may be heard within the receiver housing.
9. Allow at least one hour warmup time with the
instrument operating continuously before proced-
ing to alignment.
NOTE
The instrument is designed for continuous opera-
tion. Excessive application and disconnection of
power to the transmitter will shorten the life of the
lamp.
OPTICAL ALIGNMENT/
SIGNAL STRENGTH
NOTE
The cross hairs of the alignment scopes have
been factory set for alignment of the transmitter
and receiver. If a mirror is used with the
PW9200, a special alignment procedure is pro-
vided in the APPENDIX.
IMPORTANT
Optimum alignment must be maintained to
ensure reliable operation of the instrument. If the
instrument is misaligned, the RATIO output will
be noisy and erratic.
After the instrument has been operating continuously
for at least one hour, alignment of the transmitter and
receiver is best accomplished as follows:
1. Adjust the locking knob assembly on the back
plate of each mount so that the end of the shaft is
at least 1-1/2 inch from the front plate. (See
Figure 4 for illustration of the pan-tilt mount.)
2. With the transmitter and receiver roughly facing
each other, view the alignment target attached to
the receiver mount through the alignment scope
attached to the transmitter mount. Adjust the pan
and tilt of the transmitter housing until the cross
hairs of the transmitter alignment scope are cen-
tered on the target attached to the receiver
mount.
3. Adjust the pan and tilt of the receiver housing until
the cross hairs of the receiver alignment scope
are centered on the target attached to the trans-
mitter mount.
4. Remove the receiver window assembly by rotat-
ing counterclockwise. Avoid touching the window
with bare hands. Move the window assembly to a
safe place, being careful not to scratch the win-
dow.
5. Set the MODE selector switch on the front panel
to the ALIGN position.
6. Using the test jacks on the front panel, connect a
digital voltmeter (with a resolution of at least 1
MVDC) between the NUMERATOR (blue) and
SIGNAL GROUND (green).
NOTE
All voltage readings must be taken with a dc
voltmeter with a 10 megohm input impe-
dence. Use of other devices will give inaccu-
rate readings.
If the NUMERATOR signal is greater than 100 mV,
proceed with fine alignment as described in Step
10.
7. If the NUMERATOR signal is less than 100 milli-
volts, gross alignment may be obtained by two
people working together. Replace the window
assembly. One person should remain at the
receiver to adjust the pan and tilt of the housing.
The second person should stand at a distance of
about six feet from and facing the receiver and
sight the reflection of the transmitter lamp in the
receiver window. (Be careful to stand slightly to
one side of the beam path, so that the beam is
unobstructed.) The first person should adjust the
pan and/or tilt of the receiver until the reflection of
the transmitter lamp is visible on the receiver win-
dow. The second person should gradually back
away from the receiver, keeping the reflection
centered through pan and tilt adjustments until
10