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4-20mA Transmitters

SL-Series Toxic 4-20mA Transmitter


Designed for World-Class Performance

The SL-series microprocessor-based 4-20mA toxic gas monitors were designed to work with Gastronics line of organic electrochemical type sensors. The design criteria were set by one of the worlds leading oil companies.

The criteria included a gas monitor with a hydrogen sulfide sensor that would not go to sleep if the sensor did not see it’s target gas for a period of time. Also, it was required that the sensor would not be temperature or humidity sensitive and as a result would not require compensating circuitry. Additionally, it was desired to have a calibration mode, whereas the monitor could be calibrated without triggering alarms. A Class I, Division 2 approval was required so intrinsically safe barriers would not have to be used. The problem with Class I, Division I approvals for a Division 2 application is that even in a Division 2 area, an intrinsically safe barrier must still be used since that was how the monitor was approved.

Gastronics, Inc. gave them what they asked for as well as added some additional features that set the SL-Series Transmitters apart from the competition. First, we added an analog filter setting to allow the user to set the desired second averaging. The Monitor was made to be completely de-sensitive to radio frequency interference in order to prevent unwanted false alarms from radios on passing ships, as well as interference from hand, held radios. As a result, the SL-Series Gas Transmitter offers excellent stability with no false alarms. The SL-Series gas transmitter comes standard with a display and splash shield. Zeroing and Calibration is quick and easy using a single magnetically operated calibration point beneath the display. The setup mode, which is performed prior to installation, allows the user to specify the target gas type, range, standard calibration gas level that will be used, and any desired analog filtering. The Configuration Setup Keypad is required for pre-configuring these settings.

Features and Benefits

  • 4 – 20mA Loop powered signal output
  • Approved for CL1, Div. 2 standards
  • Requires no intrinsically safe barriers for significant cost savings when used in hazardous locations
  • 2-Wire Microprocessor-based
  • Various toxic gas sensors available

SL Series Transmitter Specifications

Weight without sensor —————————————– 1 lb. 4 oz.
Weight with sensor ——————————————— 1 lb. 7.1 oz.
Dimensions (overall in inches) ——————————– 4.93 x 6.68 x 2.25
Case material ————————————————– Powder coated aluminum
Electronics temperature rating ——————————– 40° to + 85° C
Electronics humidity rating ———————————— 0 -100%
Power requirements ——————————————- 12 – 28 VDC
Signal output ————————————————— 4 – 20 mA, 2-Wire Loop Powered
Hazard rating ————————————————– UL – 1604 Class 1, Div. 2, Gr. A,B,C,D
Warranty (Electronics) —————————————- 2 years
Warranty (Sensor) ——————————————— 1 year


10’ Sensor Extension Cable – Use to place sensor away from the electronic transmitter

SL-Series Toxic 4-20mA Transmitters

Available Sensors
Carbon Monoxide
Chlorine Dioxide
Hydrogen Fluoride
Hydrogen Cyanide
Hydrogen Sulfide
Nitric Oxide
Nitrogen Dioxide
Sulfur Dioxide