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MAS-1
MAS-1 4-20 Milliamp Soil Moisture Sensor
Affordable current-based soil moisture sensor
The MAS-1 4-20 milliamp soil moisture sensor is the first current-based sensor to use METER’s trademark 70 MHz technology. This sensor offers a standard 4-20 milliamp output that is common with PLCs and irrigation controllers. With the 4-20 mA interface, cable lengths over 250 feet are possible.
Research-grade accuracy
The MAS-1 soil moisture sensor determines volumetric water content (VWC ) by measuring the dielectric constant of the media using capacitance/frequency domain technology. The sensor uses a 70 MHz frequency, which minimizes salinity and textural effects, making the MAS-1 accurate in almost any soil or soil-less media. Factory calibrations are included for mineral soils, potting soils, and rockwool.
Low cost individual sensors for large sensor networks
The MAS-1 delivers research-grade soil moisture accuracy at a price that makes large sensor networks economically practical. You can adequately characterize your site with sensors at multiple depths and locations, even if you’re on a tight budget.
Specifications
| Interface | Standard 4-20 mA analog transmitter NOTE: Temperature measurement may not be accurate if sensor is not fully immersed in the medium of interest, due to excessively long equilibration time. |
|---|---|
| Supply Voltage | 12-32 VDC continuous |
| Output current | 4 – 20 mA |
| Overvoltage protection | Yes |
| Settling time | 4 seconds |
| Wiring | Red Wire: (+) supply Black Wire: (-) output Shield: not connected |
| Sensor type | Volumetric Water Content (VWC) |
| Range | 0-100% VWC typical |
| Resolution | Depends on current measurement (data acquisition) device |
| Accuracy | ±6% VWC with generic calibration for supported growing media up to 65% VWC, above which accuracy lessens. Increased accuracy can be achieved with a medium-specific calibration. |
| Output | 4-20 mA current proportional to VWC |
| Sensor measurement interval | 1 second |
| Operating environment temperature | -40 to 60 °C NOTE: Sensors can be used at higher temperatures under some conditions. Contact METER for more details. |
| Physical properties dimensions | 8.9 cm x 1.8 cm x 0.7 cm |
| Cable | 2 m or 5 m, 3 wire (22 AWG tinned red and black wire, 24 AWG tinned bare wire); custom cable length available upon request. |
| Measurement volume | See comparison article |
Downloads
| MAS-1 Manual | Manual | PDF, 1.106MB | Download MAS-1 Manual Manual |
| Soil sensor calibration guide | Instructions | PDF, 0.6MB | Download Soil sensor calibration guide Instructions |
| Sensor Wire Splicing Guide (Quick Method) | Instructions | PDF, 0.9MB | Download Sensor Wire Splicing Guide (Quick Method) Instructions |
| Sensor Wire Splicing Guide (Complete Method) | Instructions | PDF, 5MB | Download Sensor Wire Splicing Guide (Complete Method) Instructions |