Riken Keiki GD-84D-EX Series, Operating Manual

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11. Product Specifications 11-2 Sensor specifications
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11-2-4 Hot-wire semiconductor type
Sensor model SHF
Detection target
gas
Combustible gas Toxic gas
Detection range Depends on detection target gas.
Detection method Pump suction type
Alarm setpoints Depends on detection target gas.
Alarm accuracy
(for identical
conditions)
Within ±25 % Within ±30 %
Alarm delay time
(for identical
conditions)
Within 30 seconds Within 60 seconds
Alarm type Two-stage alarm (H-HH)
Operating
temperature range
-10 - 40 °C (no sudden changes)
Operating humidity
range
20 - 90 % RH (No condensation) (moisture content 37 °C 95 % RH or less)
NOTE
 Sensor characteristics may degrade significantly in the presence of silicon gases (organic silicon
gases), the various types of halogen gases, sulfide gases, or acidic gases.
 Select the calibration gas after accounting for typical humidity in the operating environment.

When calibrating, allow a warmup time depending on the unpowered period in clean air before
proceeding with the zero calibration and span adjustment. Refer to <Warmup time for hot-wire
semiconductor type sensors> below for warmup times.
 Readings may be affected by combustible gases other than the detection target gas.

Readings may fluctuate in the presence of fluctuations (e.g., temperature and humidity) in the
installation location.

When oxygen concentrations fall, the readings may also fall.
 Some interference may occur in the presence of highly thermally conductive gases such as CO
2
, Ar,
and He in high concentrations as base gases.
 When low vapor pressure gases are detected by aspiration, the gas may condense when aspirated
from warmer areas and detected in cooler areas, or blockages may occur in sintered alloy. Keep
vapor pressure in mind when using the product.

Indication accuracy may degrade in situations in which temperatures fluctuate significantly (±40 °C
or greater) above or below the ambient temperature in which zero calibration or span adjustment
was performed. If this occurs, repeat zero calibration or span adjustment.
 There may be fluctuations in readings if the product receives strong shocks from outside or is
subjected to vibrations. 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.

Depending on the conditions and how long the device was off, the reading may oscillate when the
power is turned on. The reading should quickly stabilize at zero.

Regardless of the detection target gas, the warranty period for SHF sensors is 3 years.