Detcon TP-624D - Manual (Page 11)

Model TP-624D
TP-624D Instruction Manual Rev. 0.4 Page 7 of 40
The more common materials that potentially cause problems with the sensors are as follows:
Silicone vapors such as those found in greases and lubricants
Halide Compounds containing Chlorine, Chlorine Dioxide, Fluorine, HF, HCl, and Bromine
Caustic and Acid liquids and concentrated vapors
Heavy metals such as tetraethyl lead
Heavy and complex VOC gasses
The presence of such contaminants in an area does not preclude the use of this H
2
S sensor technology,
although it is likely that the sensor lifetime will be shorter as a result. Use of this sensor in these environments
may require more frequent calibration checks to ensure safe system performance.
Solid State H
2
S sensors require O
2
in the background gas and the reading is affected by changing O
2
levels.
Interference Data
There are some gases typically found in industrial environments that can cause a cross-interference response
on the sensor. See the Table below for some examples.
Table 1 Cross Interference Gases
GAS PPM GAS PPM
Methane 25,000 = 0 Ammonia 500 = 1
Ethane 5,000 = 0 Diesel Fuel 1000 = 0
Hexane 5,000 = 0 Dimethyl Sulfide 4.4 = 0
Propane 5,000 = 0 Ethylene 200 = 0
Butane 5,000 = 0 Freon 12 1,000 = 0
Carbon Monoxide 1% = 0 Hydrogen 5% = 0
Carbon Dioxide 5,000 = 0 Methyl Mercaptan 10 = 0
Carbon Disulfide 14 = 0 Sulfur Dioxide 300 = 0
Methanol 500 = 5 Toluene 32 = 0
Isopropanol 500 = 3 Ethanol 500 = 5
NOTE: The Detcon MOS Sensor Cell can be damaged to the point of non-functioning if the
unit is left off power and in the presence normal air levels of moisture for periods exceeding 8
hours.
NOTE: Always protect the sensor cell with the Detcon Sealing Cap and a fresh desiccant
packet when the sensor is powered off, this will avoid permanent sensor cell damage and help
preserve the span calibration.
2.4 Mounting Installation
The TP-624D should be vertically oriented so that the sensor points straight downward. The explosion-proof
enclosure or junction box would then typically be mounted on a wall or pole (See Figure 7). Detcon provides
a selection of standard junction boxes in both Aluminum and Stainless Steel.
NOTE: Do not use Teflon Tape or any other type of Pipe Thread material on the ¾” threads
unless the unit is mounted in a severe or harsh environment. Metal-on-metal contact must be