Riken Keiki PT2-161, Руководство по эксплуатации

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10 Product Specifications 10-2. Detection principle
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10-2. Detection principle
[Catalytic Combustion Type]
When a combustible gas burns on the surface of a oxidation catalyst, the catalytic combustion type sensor
considers resultant combustion heat as temperature and resistance changes in the platinum wire coil, and
measures their gas concentrations.
This sensor detects any combustible gases. The detection range is from zero to the lower explosive limit.
When a highly-concentrated gas over the lower explosive limit comes into contact with the sensor, it may
cause a break.
[New Ceramic Type]
When a combustible gas burns on the surface of a highly active new ceramic oxidation catalyst in catalytic
combustion, the new ceramic-type sensor measures resultant temperature changes by measuring the
resistance changes in the heat-resistant alloy wire coil.
The sensor consists of two elements: A detecting element having a heat-resistant alloy wire coil with an
ultrafine particle (new ceramic) oxidation catalyst sintered on it together with a carrier and a
temperature-compensating element with a mixture of gas-inert alumina and glass sintered on it.
When a combustible gas comes into contact with the surface of the detecting element with new ceramic
oxidation catalyst sintered on it, the gas burns, causing the temperature to rise. In accordance with this
temperature change, there occurs a change in the resistance of a heat-resistant alloy wire coil that
constitutes the element. These resistance values are approximately proportional to gas concentrations.
From the changes in the resistance values, potential differences are obtained using a bridge circuit and
displayed as gas concentrations on the meter.
Oxidation catalyst
0.5~0.7mm
Structure diagram
Alumina
Platinum wire coil
0.8~1.0mm
Basic circuit
D: Detecting element
Variable resistor for bridge
equilibrium adjustment
C: Compensating
element
Fixed
resistance
Fixed
resistance
Power supply
Variable resistor for
bridge voltage adjustment
Switch
Heat-resistant material
(ceramic)
New ceramic
oxidation catalyst
1.4~1.6mm
Alumina
1.3~1.8mm
Heat-resistant alloy wire coil
Basic circuit
D: Detecting element
Variable resistor for bridge
equilibrium adjustment
C: Compensating
element
Fixed
resistance
Fixed
resistance
Power supply
Variable resistor for
bridge voltage adjustment
Switch
Structure diagram