Fast, Reliable, Longterm Stability
When you purchase a SHAW dew point sensor, you are purchasing over 60 years of proven technical experience. Alumina sensor technology, used to measure trace moisture in dry compressed air and process gases, is a great example of why you can always trust Shaw moisture meters.
Quality alumina sensor construction is critical to the performance and reliability of systems in the field. However, the design varies from manufacturer to manufacturer. Shaw moisture meters use tried and tested methods. Methods in which high-quality components are layered and treated to control the speed, sensitivity and base capacity of the sensor.
Shaw Moisture Meters manufacture the sensor base layer with a high level of precision. This precision results in a stable, reliable and drift-free trace moisture sensor. Our continuous research and development has enabled the creation of uniform and water vapor specific pores, ensuring a fast and predictable response.
The total measurement range covered by the dew point sensor is -100 °C to +20 °C (-148 °F to +68 °F) dew point, which corresponds to 0.001 ppm to 0.2 percent by volume. All areas are color coded for easy reference.
- P (Purple): -100 °C to 0 °C (-148 °F to +32 °F) DP, 0 – 6,000 ppm
- S (Silver): -100 °C to -20 °C (-148 °F to -4 °F) DP, 0 – 1,000 ppm
- G (Grey): -80 °C to 0 °C (-112 °F to +32 °F) DP, 0 – 6,000 ppm
- R (Red): -80 °C to -20 °C (-112 °F to -4 °F) DP, 0 – 1,000 ppm
- B (Blue): -80 °C to +20 °C (-112 °F to +68 °F) DP, 0 – 23,000 ppm
Key facts and unique features of SHAW dew point meters
- Flow independent
- AutoCal
- Certificate of Calibration traceable to National Physical Laboratory (NPL)
- Stability, low hysteresis and temperature coefficients
- Wide dynamic range from 0.001 ppm to 0.2 percent by volume
- Requires little or no maintenance
- Can operate over a wide range of temperature and pressure
- High selectivity for moisture
- Intrinsically safe to ATEX and IECEx (when used in conjunction with barrier or isolator)
Shaw Moisture Meters Sensor Technology
The general principle of operation of an aluminium oxide sensor, for the measurement of moisture in air and gases, is well documented but the actual construction of this type of sensor, which varies widely from manufacturer to manufacturer, is critical to the performance and reliability of systems in field operation. Certain manufacturers have resorted to catchy marketing phrases such as Hyper Thin Film Technology, Ceramic and Silicon Sensing Technology (which are simply aluminium oxide sensors on a substrate) and Thin Film technology, to demonstrate their technical competence. However, in the final analysis the performance and stability in the field of the end product is the key test.
The basic construction of the sensor consists of a high purity aluminium wire, the surface of which is chemically oxidised to produce a pore filled insulating layer of partially hydrated aluminium oxide. A porous but conductive gold film is then deposited on the oxide layer with the gold film and aluminium wire forming the two plates of a capacitor (see diagram below). The oxide layer that forms the dielectric separating layer of the capacitor, is in the form of a mass of tubular pores running up from the aluminium core to the exposed surface. Because a dynamic equilibrium is maintained between the water vapour outside the sensor and the absorbed water within it, the water absorbed into these pores is directly related to the moisture content of the gas surrounding the sensor. The general arrangement of an Aluminium oxide sensor is usually shown as below:
Specifications
- Certification: II 1G, Ex ia IIC T6 Ga
- Calibration: National Physical Laboratory (NPL); traceable calibration available
- Accuracy: Better than ± 2°C over full range
- Operating Temperature: -20°C to + 50°C
- Storage Temperature: -50°C to +70°C
- Operating Humidity: 0-90% RH non-condensing
- Mechanical Connections: M14 x 1.25mm pitch
- Electrical Connection: Male coaxial plug
- Approvals: CE and UKCA certified
- Dimensions: Overall length: 141 mm, protruding 68 mm
- Weight: Approximately 100 g
- Sensor Materials: High purity aluminium, gold, nylon,
- silver and stainless steel
Order informations
- P (Purple): -100 °C to 0 °C (-148 °F to +32 °F) DP, 0 – 6,000 pp
- S (Silver): -100 °C to -20 °C (-148 °F to -4 °F) DP, 0 – 1,000 ppm
- G (Grey): -80 °C to 0 °C (-112 °F to +32 °F) DP, 0 – 6,000 ppm
- R (Red): -80 °C to -20 °C (-112 °F to -4 °F) DP, 0 – 1,000 ppm
- B (Blue): -80 °C to +20 °C (-112 °F to +68 °F) DP, 0 – 23,000 ppm
How to order:
To order a sensor with a measuring range of -80 to 0 °C
(-112 to +32 °F) dewpoint (grey sensor) please order SE-G.
All sensors are supplied with universal guards.
NOTE:
This is the range of SHAW moisture sensors. All SHAW moisture
sensors must be used in conjunction with a SHAW hygrometer.