D-160TS-7-E
40
(
2
)
Insulation Resistance Measurement
Remove sensor leads (2 white, 1 red (black)) inside the terminal box on the meter side and make a
resistance measurement against the housing.
(
3
)
Mist release from the sensor (See Fig. 20.2 Sensor assembly.)
If the sensor collects dust, mist or other foreign matter, good practice is to blow them off from the mist
release screw opening. When the mist release screw (206) on the sensor housing is opened, metered
gas escapes to the atmosphere from the blow hole on the filter housing. Be sure to open the mist
release screw carefully and check for dust, mist or other foreign matter.
(
4
)
Filter inspection (See Fig. 20.2 Sensor assembly.)
A lifter is provided upstream of the sensor to safeguard the sensor. A dusty line should be inspected
on a regular basis as follows:
①
Totally shut off the three block valves A, B and C (203) in the sensor housing.
②
Open the mist release screw (206) to allow residue gas in the sensor to escape.
③
Remove the filter housing (205) with monkey wrench or similar tool.
④
A filter (net: 204) is lightly pressed in at the tip of the filter housing.
Remove contaminants in the filter and filter housing with an air gun or similar instrument.
⑤
Make sure of the O-ring (216) in the filter housing and then reinstall it in place.
⑥
Open block valves (A, B, C) by 1.5 turns approx. (Be sure that the mist release screw is tight in
place before attempting to open block valves.)
(
5
)
Visual inspection of the sensor (See Fig. 20.2 Sensor assembly.)
Remove the sensor unit in the following steps and visually inspect the sensor for contamination. If
your meter has a pressuretight seal, the sensor is inseparable from the terminal box on the meter
side. If this is the case, disconnect together with the terminal box.
①
Disconnect wiring (cable, conduit, etc.) to the terminal box on the meter side.
②
Totally shut off the three block valves A, B and C (203) in the sensor housing.
③
Open the mist release screw (206) to allow residual gas in the sensor to escape.
Rating: Greater than 100M Ω at 25V DC across the sensor leads grouped
(3 leads) and the housing.
If an insulation resistance meter is not available, test with a general tester.
NOTE
:
A hex wrench (JIS B 4648, nominal size 4) is required to open and close the mist release
screw.
NOTE
:
Gas remaining in the sensor housing escapes into the atmosphere. Take
necessary safety measures if hazardous gas is being metered.
CAUTION:
The following hex wrench keys (JIS B 4648) are required for the job above:
Block valve (A, B, C) application: Nominal size 5
Mist release screw application: Nominal size 4
NOTE
:
Gas remaining in the sensor housing escapes into into the atmosphere. Take
necessary safety measures if hazardous gas is being metered.
CAUTION: