65-2443 PPM Hydrogen Transmitter • 7
PPM Hydrogen Detector
The ppm hydrogen detector is a MOS type (metal oxide semiconductor) detector packaged in a 1/2
NPT nipple with a sintered metal flame arrestor on one end allowing ambient air to diffuse into the
detector. The flame arrestor also contains any sparks which may occur within the detector. The 1/2
NPT mounting threads at the top of the detector allow you to mount it into the bottom conduit hub of
the junction box. A rainshield screws onto the bottom of the detector (flame arrestor end). The
rainshield helps protect the detector from rain and debris in the monitoring environment. Three color-
coded leads extend from the top of the detector. The leads allow you to connect the detector to the
amplifier.
The detector has a built in molecular sieve that only allows hydrogen to diffuse into the detector. The
output of the detector is non-linear and is linearized by the amplifier (see below).
Amplifier
The amplifier converts the non-linear electrical output from the detector to a linear 4 to 20 mA signal
that corresponds to the detection range and transmits the signal to a gas monitoring controller. The
amplifier includes the terminal strips, span pot, linearizing pot, and test points.
Figure 2: Amplifier Component Location
Controller Terminal Strip
The controller terminal strip is a three position plug-in style terminal strip located near the top of the
amplifier. Use the controller terminal strip to wire the transmitter to a controller.
Detector Terminal Strip
The detector terminal strip is a three position plug-in style terminal strip located below the controller
terminal strip. Use the detector terminal strip to connect the detector to the amplifier.
NOTE:
The detector is factory-wired to the detector terminal strip. See page 10 for all wiring
procedures related to the transmitter.
+ Test Point, Red
R
B
W
DE
T
E
CT
OR
- Test Point, Black
Mounting Screw
w/ flat and lock washer
SPAN
P
W
R
/ S
IG
S
LI
N
E
A
R
Factory Use Jumpers
Detector Terminal Strip
Span Pot
Controller Terminal Strip
Linearizing Pot
