Sigma 120 Portable compressed air Oil Monitor

with 5″ touch screen, 0.003 mg/m³, 4…20 mA output, RS-485, alarm output, 24 VDC, transport case, connectable to S 551

The new residual oil monitor Sigma 120 monitors oil contents of compressed air and gases for spot checks, can also be used as a permanent installation unit. The simple installation and the outstanding performance makes Sigma 120 the ideal choice when residual oil contents need to be measured and monitored.

Oil free compressed air is not an easy task to be achieved. Monitoring is a must in many industries and applications to avoid contaminations in products and risks for health of humans. S 120 makes this monitoring task affordable and reliable.

For best accuracy and long term stability, the sensor applies an automatic calibration. Sensor contaminations and sensor life time are monitored and will be indicated to the user. An over range detection will remove the sampling air from the sensor to protect it against contamination.

Limits of oil vapor

Compressed air class 1 (EN ISO 8573-1): 0.01 mg/m³
Medical applications (EAB 407/1238): 0.1 mg/m³
Breathing apparatus (EN 12021): 0.5 mg/m³


Measures residual oil contents in compressed air and other gases
Can be used for permanent or in portable applications
Measures down to 0.003 mg/m3
Easy connection through sampling hose and quick connect
Output signals: – 4…20 mA
– RS-485 / Modbus / RTU
– Relay switch (NO)
PID sensor for highest accuracy
Service and Alarm indication through LED
Connectable to our displays and data loggers as well as third parties displays and control units


Medical air
Breathable air
Marine air
Food and beverage
Medical engineering
High speed trains
Semiconductor fabs
Conveyance of hygroscopic food
High tech processes
Electronics industry

Technical information

Measuring range: -0.003…10 mg/m3

Sensor type: PID (photoionization detector)

Medium: Clean dry compressed air

Operating pressure: 3…15 barg

Sample flow rate: < 2 l/min

Life time sensor: Requires service once a year

Gas temperature: -20…40 °C

Ambient temperature: -20…40 °C