SmartTemp SDI-12

Smart SDI-12/RS-485 Temperature Sensor (Water/Air)

Part # 51163

digital temperature sensor compact

The Smart Temp is a high precision digital temperature sensor that meets USGS guidelines. It features the ability to automatically sample temperature and calculate minimum, maximum, and average temperatures on a flexible time scale.

This sensor is ideal for high-accuracy readings in water, soil, and air. It features fully-potted components, robust PVC Type II housing, and marine-grade stainless steel, making the sensor ideal for harsh environments. Model 51163 is small enough to easily deploy through standard 1” (2.5cm) PVC conduit with 8” (20.3cm) factory bend corners. It also offers a loop hole which can be used to mount weights or pull the sensor through pipes or other small areas.

SDI-12 output provides universal compatibility with any SDI-12- enabled data logger and low power applications, or use the standard SDI-12 command set over an RS-485 physical interface for applications that require long cable runs or many sensors.

  • Automatic minimum, maximum, and average calculations
  • RS-485 and SDI-12 interfaces (auto-detecting)
  • SDI-12 Ver 1.4 compliant
  • Firmware updates through RS-485
  • NIST certification available
  • High-accuracy temperature measurement
  • Extremely low current draw
  • Works in water, soil, or air
  • Suitable for freshwater or marine applications
  • Fully potted electronics
  • Tough PVC Type II housing
  • Celsius and Fahrenheit output
  • No calibration required

Easily deployed through standard 1” PVC conduit with 8” factory bend corners*

digital temp sensor factory bend coners
digital temp sensor 1 inch pipe

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The Answer's in the Cloud.

eTracker is a cellular modem and "virtual" cloud-based data logger in one (meaning you don't need to install a separate data logger). Simply connect your sensor and a power source to eTracker and you're done. Configure (or reconfigure) anytime from any Internet-connected device, and use Stevens-Connect to retrieve your data, or forward it to your favorite software system.

Technical Specifications

Power requirements

9 - 30 VDC


4-20 mA current signal, linearly corresponding to range

Operating temperature

-40° F to 185° F (-40° C to 85° C)

Compensated temperature

32° F to 122° F (0° C to 50° C)


0-2.5 ft range: 0.2% max.
0-5 ft range: 0.2% max.
0-10 ft range: 0.2% max.
0-35 ft range: 0.3% max.
0-50 ft range: 0.3% max.
(0.1% typical for all ranges)

Repeatability & hysteresis

Typical: ± 0.2% span

Reverse polarity protection

Built into sensor


0-2.5 ft: 20 psi max.
0-5 ft: 20 psi max.
0-10 ft: 20 psi max.
0-35 ft: 45 psi max.
0-50 ft: 45 psi max.


Qualification tested to 150 g


Red: power
Green: 4-20 mA return
Silver: drain wire

Pipe threading

1/2-14 straight pipe thread (back of sensor housing near cable)
3/8-18 straight pipe thread (under removable copper nose-cone)

Physical size

4.00" L x 0.84" dia. (101.6 mm L x 21.33 mm dia.)


Probe: 2.37 oz (61.19 g)
Cable: 0.43 oz (12.19 g) per foot (.4 g per cm)
(weights are approximate)