6 Maintenance
6-3. Replacement parts
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6-3. Replacement parts
<Sensor Replacement>
Replace the gas sensor according to the following procedure.
(1) Turn off the indicator/alarm unit power.
(2) If drip-proof cover (round, square) and direct insertion unit is used, remove a detector head.
Loosen the two hexagon socket head bolts on the sensor guard of the detector head and remove the
sensor guard. (The hexagon socket head bolts on the sensor guard do not drop off even when they are
loosened.)
(3) Pick the top (sintered metal part) of the gas sensor with deteriorated sensitivity with fingers and pull it
out. A rubber seal is attached to the sensor guard. (A rubber seal without deformation or damage will
be used again. Be careful not to lose it.)
(4) One of the five pins of the gas sensor is longer than the others. With this long pin positioned farthest
from the cable inlet (see figure below), insert it lightly (shallowly) to the socket in the hole of the main
unit. Then push the gas sensor to insert it deep in the socket.
(5) Put the sensor guard over the gas sensor and tighten the two hexagon socket head bolts securely.
(6) When the replacement of gas sensor is completed, turn on the indicator/alarm unit power to check the
gas sensor voltage or current. (See the operating manual of the indicator/alarm unit.)
(7) Warm up the unit for one hour or so (guide value) after power-on. After that, perform the zero and span
adjustments according to "6-2. Calibration method".
NOTE
After the sensor is replaced, the voltage, zero and span adjustments must be performed.
We recommend the sensor replacement be performed by RIKEN KEIKI.
Long pin
Bottom view of
gas sensor
Cable inlet
Hole of main unit
WARNING
Do not replace the sensor while it is energized.
Doing so may cause ignition, thus leading to dangers.
Before replacing the sensor, be sure to turn off the sensor power (indicator/alarm unit power) .
