Semi-Conductor NH₃
SB-NH₃-2%(20,000 pm)-N1

The SB-NH₃ gas sensor incorporates a conductive oxide that does NOT utilize a catalyst and is supplied with a matched pre-amp. Even though the sensor output is non-linear, the pre-amp converts this to a linear 4/20 mA output. The SB is recommended for high trip level engine room applications only. Room must be well ventilated.

Characteristics

• Sensor life is typically 2-3 years plus. Continuous exposure of the sensor to NH₃ does NOT harm the SB.
• This sensor is minimally affected by moisture or temperature changes, but must be located in well-ventilated areas.
• The SB sensor is minimally affected by hydrogen, methane, ethylene, chlorine, ozone, carbon monoxide, carbon dioxide, propane, and butane.
• Short-term exposure to alcohols, vinegars and solvents is not a problem in smaller concentrations and where the exposure is not continuous, but be cautious in applying these sensors if there is a possibility of exposure to alcohol-based floor cleaning solutions, some spray cleaners, contact cleaners, degreasers, or paints. (Even latex paints contain alcohol.)
• The sensor is still sensitive to H₂S.
• Range is 20,000 ppm (2%), with trip levels of 1% and 2%.
• The SB sensor has an enhanced sensitivity as it ages, i.e., it becomes more sensitive, not less.

Where to apply

• The SB should be applied only in highly ventilated engine rooms where ventilation air comes directly from the outside.
• The SB sensor should be ideal for machine rooms or vessel rooms, but only for high level trips. The key for long term success is fresh air. This sensor should not be used for electrical shutdown subsequent to high ammonia concentrations.
• The most common damage to SB sensors is in new machine rooms during application of piping insulation. Solvents and silicone sealers used in this process damage the sensor beyond repair.