Hot-Wire Liquid Water Content Sensor

This compact instrument captures direct measurements of liquid water content (LWC) from 0.05 g/m3 to 3 g/m3, a critical bulk property in atmospheric research.


Easily mount the LWC-301 on manned or unmanned aircraft, cooling towers, and spray rigs.

Make replacement quick and easy with an interchangeable circuit card sensor.

Get a self-contained aspirator for ground-based LWC applications – with an external flow indicator that provides easy access to airflow readings.

Hotwire sensing

  • The LWC-301 features a coiled wire that is maintained at 150 °C, which acts as variable resistance in a Wheatstone Bridge circuit.
  • The resistance of the sensing coil is directly proportional to its temperature.
  • Power dissipated by the sensor to maintain temperature is used to calculate vaporization, and in turn, liquid water content.
Measured Parameters Liquid water content in the 0-3 g/m3 range
Air Speed Range 0 - 200 m/sec
Calibration Not Required
Frequency Response >25 Hz
Output RS-422 Serial Communication
Special Features Interchangeable circuit card sensor Pulse width modulation control (avoids overheating of the power transistor and hotwire coil)
Mounting 2.5-inch diameter B.C. Rosemount pattern mounting
Power Requirements System power: 28 VDC, 7.5 A max Anti-ice power: 28 VDC, 8.0 A
Weight Electronics box: 500 g Sensor strut: 600 g
Dimensions Sensor strut with strut mount: 11.5 cm W x 6.4 cm L x 19.5 cm H (41/2” W x 2 1/2” L x 7 5/8“ H) Electronics box: 12.1 cm W x 12.1 cm L x 6.7 cm H (43/4” W x 43/4” L x 25/8” H) Electronics box mounting plate: 9.7 cm W x 15.3 cm L x 0.3 cm H (3.8” W x 6.0“ L x 0.1” H)
Operating Limits 0 -12 km altitude -40 to +40 °C 0 - 100% RH

PADS software and laptop

The Lifecycle Care Program ensures LWC integrity and performance vital to your research mission for 3 years or 3 calls (whichever comes first). When conducting complex and time intensive laboratory or field measurements it is critical to avoid down time, and ensure data collection accuracy. The program consists of 3 key deliverables for each year or call:

  • Instrument Logistics
  • Instrument Integrity
  • Instrument Performance

Lifecycle Care Program Includes:


  • Shipping to and from Droplet Measurement Technologies facility
  • Customs handling, including CARNET ATA if required


  • Incoming instrument evaluation and health check


  • Software and firmware validation
  • 100%-unit functionality test
  • Calibration data
  • Calibration report
  • Certificate of calibration

At times, our technician might discover an instrument issue, which might not be covered by the Lifecycle Care Program or by our product warranty. In such case we will reach out to you with a service & repair estimate to allow you to provide us with the next steps of action.