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QTS - 1710
QTS - 1710 COMBUSTIBLE TRANSMITTER/SENSORS

The QTS - 1710 Series utilizes catalytic pellistor bead technology for the measurement of combustible gases. The standard sensor is resistant to poisoning substances such as silicones, sulfur compounds, and chlorinated compounds. It is mounted in an explosion-proof housing rated Class 1, Division 1, Groups A, B, C, D. The transmitter provides a 4-20 mA DC output linear to the LEL (Lower Explosive Limit) of the calibrated combustible gas. The analog transmitter operates on a power supply of 12-30 VDC in a three wire configuration and is mounted in an explosion-proof housing rated Class 1, Division 1, Groups B, C and D. Test jacks are provided to monitor the transmitter signal without interrupting the output.

GAS SELECTION TABLE

GAS TYPES

# 100% LEL
IN % VOLUME
DETECTION
CONSTANT
Methane 0 5.0% 112
Acetylene 1 2.5% 63
Ethane 2 3.0% 76
Propane 3 2.1% 62
n-Butane 4 1.6% 66
n-Pentane 5 1.5% 51
n-Octane 6 1.0% 42
Hydrogen 7 4.0% 86
Gasoline 8 1.3% 44
Other 9 Advise Advise

 

PRINCIPLE OF OPERATION

Sensor assemblies consist of two matched pellistor beads, each encasing a coiled platinum wire. One of the beads is coated with platinum as a catalyst. Both elements are exposed to the same environmental conditions and heated with the platinum wire. The elements are connected to two nodes of a Wheatstone Bridge on the transmitter electronics, measuring the resistance of each element. When combustible gas is introduced to the elements, the catalyst coating on one bead will cause oxidation. This will raise the temperature of the element, increasing the resistance. This oxidation does not appear on the bead without the coating. The resultant difference in resistance is proportional to the concentration of combustible gas. The electronics provides a null adjustment to balance the resistance of the two elements in clean air conditions. The resistance differential is linearized and converted into a 4-20 mA DC signal proportional to a 0-100% LEL concentration of the target combustible gas. Zero and span adjustments are provided to calibrate the transmitter for a specific combustible gas.

SPECIFICATIONS

Input Power: 12 to 30 VDC, 125 mA maximum
Output Signal: 4 to 20 mA DC into 700 ohms at 24 VDC, Three-wire configuration
Enclosure Rating: S-NEMA Type 4x Weatherproof, Type 7 and 9 Explosion Proof;
Class 1, Div. 1, Groups B, C,   D 316 Stainless Steel Sensor
Housing is also Group A rated
Enclosure Materials: S-Cast Aluminum, Epoxy Coated
Sensor Technology: Dual element poison resistant catalytic pellistor bead
Sensor Gas Types: Hydrocarbon combustible gases
Response Time: Less than 10 seconds to register 50% of a full scale step change
Less than 30 seconds to register 90% of a full scale step change
Sensor Life: Typical 3 to 5 years
Temperature: -40 to +104 F (-40 to +40 C)
Humidity: 0 to 99% RH, non-condensing
Pressure: Atmospheric 10%
Accuracy: 1 % LEL Methane
Repeatability: 1 % LEL Methane
Zero Drift: <2% of range/month at 68 F (20 C)
Shipping Weight: 5 lb. (2.3 Kg)
Approvals: CSA

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Last Updated 03/18/10