S120 Residual Oil Sensor

S 120 residual oil sensor

The new residual oil sensor S 120 monitors oil contents of compressed air and gases permanently or for spot checks when used as portable unit in conjunction with S 551. The simple installation and the outstanding performance makes S 120 the ideal choice when residual oil contents needs 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.


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

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

Product features

  • 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 CS-iTEC displays and data loggers as well as third parties displays and control units


Technical data

Technical data S 120
Measuring range 0.003 … 10.00 mg/m³
Sensor type PID (photoionization detector)
Detection limit 0.003 mg/m³
Accuracy 5% of reading +- 0.003 mg/m³
Operating pressure 3 … 15 barg (higher pressure on request)
Gas humidity < 40% rel. humidity, no condensation
Sample flow rate < 2 l/min, measuring gas is released to ambient
Gas connection 6 mm quick connect
Electrical connection M12 connector
Sensor life time 6000 operating hours. Will be indicated. Sensor exchange by service
Gas temperature -20 … 50 ºC (at inlet)
Ambient conditions -20 … 50 ºC
Transport temperature -30 … +70 °C
Output signal 4…20 mA (0 … 10 mg/m³)
RS-485, Modbus/RTU
Relay: NO, 32 VDC / 500 mA
Power supply 24 VDC ± 5%, 8 W
Display & data logger 5” touch screen, 100 million values (option)
Application Downstream of activated carbon filters
Downstream of oil-free compressors
Wherever upstream drying and filtration is applied
Casing/dimensions PC, Al alloy, 271 X 205 X 91 mm
Classification IP65
EMC According to IEC 61326-1
Settings Various sensor settings can be performed
through SUTO-iTEC display units or through the
related service software
Weight 2400 g
Sample rate 1 s