The S120 oil vapor sensor monitors the oil content of compressed air and gases permanently or for spot checks when used as a portable unit in conjunction with S551. For best accuracy and long term stability, the S120 sensor applies an automatic calibration. Sensor contaminations and sensor life time are monitored and indicated to the user. An ‘over range’ detection removes the sampling air from the sensor to protect it against contamination. The simple installation and outstanding performance makes the S120 the ideal choice when oil vapor content needs to be measured and monitored.