Stationary
Humidity in gases
FL 510
Industrial humidity and temperature transmitter for gases up to 300 bar.
- Measuring range
- 0…100 % RH, 0…125 °C
- Accuracy
- ± 1.8 % RH
- Pressure
- 300 bar
- Outputs
- 2 × 4…20 mA, Modbus-RTU
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- Humidity in gases and oil
Humidity measurement
Humidity meters for gases, oil and rooms
Too much moisture in oil shortens machine life, too much moisture in process gases spoils the process. FL 510 and FO 510 measure humidity and temperature directly in the process – up to 300 bar and 125 °C.
- FL 510 in gases
- 0…100 % RH
- FO 510 in oil
- 0…1 aw
- pressure resistance
- 300 bar
Why measure humidity
Capacitive sensor – stable and media-independent
The FL 510 measures relative humidity and temperature in non-corrosive gases – in gas pipelines and storage tanks, evaporation processes, inert nitrogen or argon atmospheres, electronics production and laboratories. The capacitive sensor is long-term stable and independent of the gas type.
The FO 510 measures moisture in oil as water activity aw – independent of oil type and age – in transformer, engine, lubricating and hydraulic oil and diesel fuel. For transformer oil it also calculates the water content in ppm.
- Two 4…20 mA outputsFreely configurable outputs and Modbus-RTU for humidity, temperature or dew point.
- Up to 300 bar and 125 °CInstalled directly in the process, without taking a sample.
- Water activity awMeasurement in oil does not depend on oil type or age.
- IP 66Robust housing for industrial environments.
CS Instruments models
CS Instruments humidity meters
Sensors for humidity in gases and oil and an ambient sensor for the compressor room. For very dry compressed air, use a dew point sensor.
Stationary
Moisture in oil
FO 510
Industrial oil moisture sensor (water activity aw), independent of oil type and age.
- Measuring range
- 0…1 aw, 0…125 °C
- Accuracy
- ± 0.02 aw
- Pressure
- 300 bar
- Outputs
- 2 × 4…20 mA, Modbus-RTU
Stationary
3-in-1 ambient sensor
IAC 500
Absolute pressure, temperature and humidity in the compressor room – for accurate compressor performance assessment.
- Temperature
- -20…+60 °C, ± 1 K
- Relative humidity
- 5…95 % RH, ± 3 %
- Absolute pressure
- 300…1100 hPa, ± 4 hPa
- Outputs
- Modbus-RTU, PoE
Stationary
Stationary dew point sensor
FA 510 / FA 515
Pressure dew point sensor for refrigeration, membrane and adsorption dryers, with Modbus-RTU and IO-Link.
- Measuring range
- -80…+20 / -20…+50 °Ctd
- Accuracy
- ± 1 °Ctd (+50…-20 °Ctd)
- Pressure
- -1…50 bar (500 bar)
- Outputs
- 4…20 mA, Modbus-RTU, IO-Link
Comparison
Humidity meter comparison
| Model | Version | Measuring range | Accuracy | Pressure | Outputs |
|---|---|---|---|---|---|
| FL 510 | Stationary | 0…100 % RH, 0…125 °C | ± 1.8 % RH | 300 bar | 2 × 4…20 mA, Modbus-RTU |
| FO 510 | Stationary | 0…1 aw, 0…125 °C | ± 0.02 aw | 300 bar | 2 × 4…20 mA, Modbus-RTU |
| IAC 500 | Stationary | – | – | – | Modbus-RTU, PoE |
| FA 510 / FA 515 | Stationary | -80…+20 / -20…+50 °Ctd | ± 1 °Ctd (+50…-20 °Ctd) | -1…50 bar (500 bar) | 4…20 mA, Modbus-RTU, IO-Link |
Humidity or dew point?
Which humidity parameter to choose
Relative humidity and dew point describe the same water in a gas – they differ in where each makes sense.
% RH
Relative humidity
For gases in pipelines and tanks, inert atmospheres and rooms. FL 510 or IAC 500 sensor.
°Ctd
Pressure dew point
For dried compressed air after the dryer – here relative humidity is too low for a meaningful measurement. FA 510 sensor.
aw
Water activity in oil
For hydraulic and lubricating oils. The FO 510 sensor shows how close the oil is to water saturation.
How to choose
How to choose a humidity meter
Medium
Gas or air: FL 510. Oil: FO 510. Compressor room: IAC 500.
Dryness level
Below about 0 °Ctd choose the FA 510 dew point sensor.
Pressure and temperature
FL 510 and FO 510 withstand up to 300 bar and 125 °C.
Signal
2 × 4…20 mA for a PLC or Modbus-RTU for the DS 500 data logger.
FAQ
Humidity measurement questions
What is the difference between relative humidity and dew point?
Relative humidity tells you how much water is in a gas compared with the maximum possible amount at the same temperature. The dew point is the temperature at which this water would start to condense. For dry compressed air, the dew point is the more accurate parameter.
What does water activity aw in oil mean?
Water activity from 0 to 1 tells you how close the oil is to water saturation. At 1, free water starts to separate. The measurement is independent of oil type and age.
Can the FL 510 measure in compressed air?
Yes, the FL 510 is pressure-resistant up to 300 bar. For very dry air after an adsorption dryer, however, we recommend the FA 510 dew point sensor with a range down to -80 °Ctd.
Related measurements
What else we measure in a compressed air system
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