Fast, Reliable, Longterm Stability
The SHAW AcuDew high performance dewpoint transmitter. A robust and reliable, 2 wire, 4-20 mA loop powered transmitter.
Utilising the ultra high capacitance SHAW moisture sensing technology, the AcuDew offers superior sensitivity, accuracy, repeatability and speed of response.
This dewpoint transmitter incorporates the SHAW AutoCal feature. AutoCal allows users to check the span of the instrument and correct for any deviation between annual laboratory calibrations. Notably, you can AutoCal dewpoint instruments in situ and without the need for skilled personnel or special equipment.
Various dewpoint ranges are available covering an overall range from -120 °C to +20 °C (-184 °F to +68 °F) dewpoint and output units are configurable in °C dewpoint, °F dewpoint, ppm(V), ppb(v), g/m³ and lb/MMSCF.
Built of stainless-steel, its strong construction includes an industrial M12 connector. SHAW designed the dewpoint transmitter to withstand extreme environmental conditions and harsh environments, manufacturing the AcuDew with a protection rating of IP66 (NEMA 4X). The M12 connector reduces the setup time, saving you time when installing and maintaining wiring systems.
The AcuDew dewpoint transmitter provides a linear, 4 – 20 mA signal over the chosen measurement range and is loop powered by a 7-28 V DC source (24 V option is available). If your requirement includes installation in a remote location, the 4-20 mA signal is ideal for data transmission over long distances (up to 1,000 metres (3,280 feet)) without signal degradation. Additional benefits of a 4-20 mA current loop include: resilience against any background electrical noise and easy fault detection if the loop is broken.
Whether you wish to install the dewpoint transmitter directly in to the process line or combine as part of a sample conditioning system, the AcuDew is easy to operate and requires little or no maintenance.
Our dewpoint transmitter is tested to withstand pressures up to 35,000kPA (350 bar) and can be connected directly into pipelines. Another key point is the absence of controls to operate during use, this is because we designed the AcuDew for long term unattended operation.
The AcuDew is supplied ready to use with a Certificate of Calibration traceable to National and International Humidity Standards, instruction manual and two metres of cable.
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
Dew Point Sensor
- Sensing Element: Shaw Ultra High Capacitance - Aluminium Oxide Sensor
- Ranges: Dewpoint = 0.1 °C/0.2 °F resolution via the potentiometer on the transmitter body
- ZD: -100 °C to +20 °C (-148 °F to +68 °F) dewpoint
- HD: -65 °C to +20 °C (-85 °F to +68 °F) dewpoint to National Physical Laboratory (NPL)
- Go (Gold) -120 to -20 °C (-184 to -4 °F) dewpoint 0.1 ppb - 1,000 ppm(V)
- P (Purple): -100 to 0 °C (-148 to +32 °F) dewpoint 0 - 6,000 ppm(V) (-130 °F to +68 °F)
- S (Silver): -100 to -20 °C (-148 to -4 °F) dewpoint 0 - 1,000 ppm(V)
- G (Grey): -80 to 0 °C (-112 to +32 °F) dewpoint 0 - 6,000 ppm(V)
- R (Red): -80 to -20 °C (-112 to -4 °F) dewpoint 0 - 1,000 ppm(V)
- B (Blue): -80 to +20 °C (-112 to +68 °F) dewpoint 0 - 23,000 ppm(V)
- MP: 0.1 to 100.0 ppm(V) 0.1 ppm resolution
- LP: 0.01 to 10.00 ppm(V) 0.01 ppm resolution
- GH: 0.01 to 10.00 g/m³ 0.01 g/m³ resolution Dry to wet: -100 °C to -20 °C - less than 20 secs
- LB: 0.1 to 100.0 lb/MMSCF 0.1 lb/MMSCF resolution
- AutoCal: Field calibration/span check facility. Activated and operated
- Factory Calibration: Supplied with Certificate of Calibration traceable
- Accuracy: ± 2 °C (±3.6 °F) dewpoint NPL traceable -90 °C to +20 °C
- Temperature Coefficient: Temperature compensated for operating range
- Resolution: 0.005 mA
- Repeatability: Better than ±0.3 °C (±0.54 °F) dewpoint
- Operating Temperature: -20 °C to +60 °C (-4 °F to +140 °F)
- Storage Temperature: -20 °C to +70 °C (-4 °F to +158 °F)
- Response Times: Wet to dry: -20 °C to -60 °C - less than 120 secs
- Sample Flow Rate: Flow independent but ideally 2 to 5 litres per minute. max: 25 litres/min
- Calibration Warranty: 12 months from date of dispatch
Electrical
- Electromagnetic Compatibility (EMC): Immunity: complies with
- Isolation: Sensing element connected to the 4-20 mA loop but isolated EN 61326-1:2013 Emissions: complies with EN 61010-1:2010 from transmitter body
- Warm Up Time: 10 seconds
- Output Signal: 4-20 mA Linear
- Fault Conditions: Open circuit/under range: output drives to 20.5 mA
- Operating Voltage: 7-28 V DC reverse polarity protected Short circuit/over range: output drives to 20.75 mA
- Approvals: CE, UKCA
- Maximum Series Resistance: = {40 x (Supply Voltage – 7)} Ω
Mechanical
- Operating Pressure: From 1kPa (0.01 barA) to maximum 35,000kPa (350 barA)
- Operating Humidity (External): Maximum - 95% RH non-condensing
- Cable Terminations: IP66/NEMA 4X rated, M12 five pin cable connector at the transmitter and the other end terminated with bootlace ferrules
- Cable: Supplied with 2m standard cable. Nominal diameter 3.4mm, 92 Ω/km at 20°C
- Transmitter Enclosure: 316 stainless steel body with five pin integrated cable plug
- Sensor Protection: 316 sintered stainless steel filter - 50 micron
- Probe Material (Wetted Parts): 316 stainless steel
- Weatherproof Classification: IP66 (NEMA 4X) when connector mated to transmitter
- Mechanical Connection: 3/4” UNF (16tpi) with integral Viton “O” ring seal
- Mechanical Warranty: 24 months in case of faulty workmanship and defective parts
- Weight: 215 grams (0.474 lb) includes connector
Dimensions
How to order AcuDew?
AcuDew - (Range)
R - Choose the required range:
ZD: -100 °C to +20 °C (-148 °F to +68 °F) dewpoint
HD: -65 °C to +20 °C (-85 °F to +68 °F) dewpoint
Go (Gold) -120 to -20 °C (-184 to -4 °F) dewpoint 0.1 ppb - 1,000 ppm(V)
P (Purple) -100 to 0 °C (-148 to +32 °F) dewpoint 0 - 6,000 ppm(V)
S (Silver) -100 to -20 °C (-148 to -4 °F) dewpoint 0 - 1,000 ppm(V)
G (Grey)G (Grey) -80 to 0 °C (-112 to +32 °F) dewpoint 0 - 6,000 ppm(V)
R (Red) -80 to -20 °C (-112 to -4 °F) dewpoint 0 - 1,000 ppm(V)
B (Blue) -80 to +20 °C (-112 to +68 °F) dewpoint 0 - 23,000 ppm(V)
MP: 0.1 to 100.0 ppm(V)
LP: 0.01 to 10.00 ppm(V)
GH: 0.01 to 10.00 g/m3
LB: 0.1 to 100.0 lb/MMSCF
Example:
To order an AcuDew with a measuring range of -80 °C to 0 °C
(-112 °F to +32 °F) dewpoint (grey sensor), please order as
AcuDew-G