Non-Submersible Pressure Transducer (H-3521)

WaterLOG Non-Submersible Pressure Transducer (H-3521)

The WaterLOG® Non-Submersible Pressure Transducer (H-3521) is an SDI-12 compatible, NIST traceable pressure sensor. The Transducer was designed to directly measure water, antifreeze or other fluid pressure with an accuracy better than 0.03% FSO. The Transducer allows extended SDI-12 commands for setting the Stage to the current water elevation or pressure at your site. And to make things even easier, the SDI-12 output provides measurement data in user-defined units.In addition, it's built-in temperature compensaion, wide variety of standard mode outputs, and user friendly RS-232 programming menu interface make the Transducer attractive for an array of sites.

  • Features
  • Specifications

Designed to accurately measure culinary, artesian well, piezometer, snow pillow and dam water level, the WaterLOG® Non-Submersible Pressure Transducer (H-3521) incorporates SDI-12 compatbility with NIST traceable features.


  • Accuracy over temperature range exceds 0.04 ft (12mm) of water
  • RS-485 programmable for MODBUS slave
  • Standard mode ourputs: SDI-12, 4-20mA, RS-485 and RS-232
  • Optional outputs: 0-5V and Quadrature
  • Programmable continuous outputs
  • Low current operation (less than 200µA standby)
  • Programmable averaging
Pressure Less than or equal to 0.03% of full scale output (FSO) over temperature range
Pressure Hysteresis Less than 0.02% of FSO
Linearity Less than 0.05% deviation
Temperature Internal temperature ±1° C over tem­perature range
Long-term Stability Drift is less than ±0.10% of FSO per year
Standard Pressure Ranges are 15 PSI and 30 PSI
Custom calibration ranges available
Pressure 1 part in 1,000,000 (0.0001%)
Temperature 1 part in 1,000,000 (0.0001%)
0 to 15 PSI 0 to 34.6 ft. (10.54 m) ±0.017 ft. (5.18 mm)
0 to 30 PSI 0 to 69.20 ft (21 m) ±0.035 ft. (10.67 mm)

4.76 in W x 4.76 in L x 2.5 in H

12mm W x 12 mm L x 6.35 mm H

Weight 2 lbs (.91 kg)

Housing: Fiberglass

Atmospheric Vent: Sintered bronze, #10-32


7-pin circular: Power, SDI-12, 4-20 mA and RS-485
3-pin circular: RS-232 Communications port

Cables: Main connector cable with 6 ft. (1.84 m) pigtail is provided.

RS-232 connector cable optional.

Connectors: Sealed Bendix type circular

Pressure Inlet: 1/8 in. (38.1 mm) female NPT

Power Requirements
Voltage Input 10 to 16.5 V DC

Sleep Mode: 500 µA

Active: 15 mA max

Bias Mode: 1.5 mA max

Surge Protection Built in, 1.5 KVA
Baud Rate 1200
Protocol SDI-12 V1.3, 7-bit even parity, 1 stop bit
Output Voltage Level

Minimum high level: 3.5 volts

Maximum low level: 0.8 volts

Response Time SDI-12:  6-second measurements sequence (programmable)
RS-485 Interface
Baud Rate Programmable (default=9600)
Protocol  Modbus RTU
Port RS-485
RS-232 Interface
Baud Rate 9600
Protocol RS-232, 8 bit, No Parity, 1 stop bit
0-5V Analog Output (Optional)
Resolution 1 part in 4096 (0.02%)
Accuracy ±0.025%
4-20mA Output
Type 4-20mA, optically isolated
Loop Voltage 8.0V min 35V max
Resolution 1 part in 4096 (0.02%)
Accuracy ±0.025%
Quadrature Output (Optional)
Output Voltage Low: 0.4 (Max) @-5mA
High: 2.5(Min)@5mA
General Specifications
Operating Temperature -30 ° to +60 ° C
Compensated Range -30 ° to +60 ° C
Storage Temperature -40 ° to +80 ° C
Pressure Overload Less than 2 times the rated pressure
Media Capability Liquid and gases
Rating NEMA 4 enclosure
Warranty The WaterLOG® Non-Submersible Pressure Transducer (H-3521) is warranted against defects in materials and workmanship for twenty-four months from date of shipment.

Options & Accessories


3-Conductor Interface Cable; RS-232


7-Conductor Interface Cable; Power, SDI-12, Control