Riken Keiki GD-3EC, Technical Manual

Page: 156 / 177

10. Product Specifications 10-3 Detection target gases for individual detection principles
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10-3-3 Semiconductor type
Sensor
model
Gas name
Gas
symbol
F.S. 1 digit
First
Alarm
setpoint
Second
Alarm
setpoint
Calibration
gas
Operating
temperature
range
Operating
humidity
range
Years of
warranty
SGF-8581 Methane CH
4
2,000 ppm 10 ppm 500 ppm 1,000 ppm CH
4
−20 °C - 65 °C
20 %RH -
95 %RH*
(no
condensation)
3 years
SGF-8562
Carbon
disulfide
CS
2
200 ppm 1 ppm 50 ppm 100 ppm CS
2
SGF-8563
Ethylene
oxide
EO 100 ppm 1 ppm 25 ppm 50 ppm EO
SGF-8562
Hydrogen
sulfide
H
2
S 100 ppm 1 ppm 25 ppm 50 ppm H
2
S
*Absolute humidity not exceeding 46 g/m
3
(equivalent to 37 °C, 95 %RH)
NOTE
 The sensor characteristics may deteriorate significantly if silicone gases (organic silicone gases), halogen
gases, sulfide gases, or acid gases are present.

A silicone removal filter and activated carbon filter are available as options.

Prepare the calibration gas to suit the humidity of the environment in which it will be used.
 When calibrating, allow the product to warm up for a period of time corresponding to the length of time
turned off in clean air before performing zero calibration and span adjustment. For information on
appropriate warmup times, refer to the <Semiconductor type sensor warmup times> table below.

The reading may change even for combustible gases other than the detection target gas.
 The reading may change even for ambient fluctuations (e.g., temperature and humidity) in the installation
location.
 The reading may fall as the oxygen concentration decreases.

Interference may occur if gases with high thermal conductivity, such as high-concentration CO
2
, Ar, or He,
are present as the base gas.
 In detecting gases with low vapor pressure by the suction method, the gas may form a mist when drawn in
from the high-temperature side and detected at the low-temperature side, possibly forming condensation
inside the sensor or causing clogging due to sintering. Keep vapor pressure in mind during use.
 Perform maintenance if a warning appears while the life assessment or self-diagnostic function is active.
 Use the combustible gas sensor adapter when calibrating. Calibration accuracy may be reduced without
the combustible gas sensor adapter.

Reading accuracy may be reduced if temperature fluctuations exceed ±20 °C with respect to ambient
temperature following zero calibration or span calibration. If this occurs, repeat zero calibration or span
adjustment.
 Readings may fluctuate if the product is subjected to strong external impact or vibration. If this occurs,
perform zero calibration and span adjustment.
 The zero point may fluctuate if the sensor comes into contact with high-concentration gas continuously
for extended periods. If this occurs, perform zero calibration and span adjustment.

Readings may fall in environments where gas is continuously present.

The sensor may be hot during replacement. Be careful to avoid burns when replacing the sensor. If the
sensor is hot, turn off the power and wait for it to cool.
 The top of the sensor has a Teflon coating. Sensor characteristics may be affected if the Teflon coating is
damaged. Take care to avoid pressing on the Teflon coating with excessive force or damaging it with
sharp implements.
 Calibration is not possible if the reading during calibration does not exceed the zero suppression value.
If the reading is below the zero suppression value when the desired calibration gas is introduced for
calibration, first calibrate using a gas that gives a reading higher than the zero suppression value, then
calibrate using the desired calibration gas.
 Regardless of the detection target gas, the warranty period for SGF sensors is 3 years.