compressed air installations oil & oil dew continuous compliance monitoring & control systems

Sigma Compressed Air Oil Supervisor

Continuous oil content measurement in flowing air
Continuous oil content measurement in flowing air

Compressed Air Oil Content Quality to ISO 8573 class 1 and class 0 On-Line Compliance?


Having an oil free compressor does not necessarily mean that your compressed air is oil free as the term “oil-free compressor”  refers only to the compression chamber, not the compressor system as a whole, or the resulting compressed air quality.

Contaminants in the compressed air system generally can be attributed to:
  The quality of the air drawn into the compressor
  The operation of the air compressor
  Compressed air storage devices and distribution systems


Keep in mind that most of the millions of particles in normal urban ambient air your compressor sucks in, are below the pore size of the compressor inlet filters.
Hydrocarbon content in ambient air varies from area to area (typically contains between 0.05mg/m3 and 0.5mg/m3 of oil vapor from sources such as car exhausts and industrial processes) but is often sufficient to contaminate the compressed air of your system. Ofcourse, the answer to that, is an air treatment system downstream, but how do you know that your air quality complies with the requirements of oil free air 24hours/day 365 days/year?

Many industrial processes are very sensitive to oil contamination, as this can lead to tremendous risks, downtime, product spoilage & recall, damage the company's reputation, harmed consumers & product liability, but up to now the only method for measuring the in-pipe oil content involved specialist equipment and  a time-consuming laboratory analysis.

Online measuring and monitoring device for compressed air oil content


Sigma 120 Series air Oil Monitor

with 5" touch screen, 0.001 mg/m³, 4...20 mA output, RS-485, alarm output, 24 VDC,


The new residual oil monitor Sigma 120 monitors oil contents of compressed air and gases and can also be used as portable. The simple installation and the outstanding performance makes Sigma 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 contamination 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 contamination 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 0.001 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
  • Pharmaceuticals
  • 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:         -0.001...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






A "must"  compressed air quality continuous monitoring system for facilities that need clean air without contaminants, at all times, and regulatory compliance validation with ISO 8573:2010 Part 2+5, HTM 02/01 , HEDIS, NCQA accreditation 24/7,Level 1 NFPA Medical Compressed Air Systems, GMP-Facility and Manufacturing Excellence.فى الامتثال لاين؟