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.
Parameter Specification
Measured Parameters

Liquid water content in the 0-3 g/m3 range

Air Speed Range

0 – 200 m/sec


Not Required

Frequency Response

>25 Hz


RS-422 Serial Communication

Special Features

Interchangeable circuit card sensor
Pulse width modulation control (avoids overheating of the power transistor and hotwire coil)


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


Electronics box: 500 g
Sensor strut: 600 g


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

Droplet offers a three-year service plan to ensure that your LWC-301 continues to deliver high-quality data. This plan locks costs upfront at the time of funding application and covers annual calibration, alignment, cleaning, wear-item replacement, calibration documentation, and shipping. Specific services provided for the LWC-301 include:

  • Shipping to and from Droplet facility for service
  • Incoming instrument evaluation and health check
  • Heater resistance observations and adjustments
  • Hardware replacement
  • Light test performed
  • O-ring replacement
  • Wind tunnel test
  • Software, firmware, and antivirus update
  • 100% unit functionality test
  • Calibration data, Wind Tunnel Report, Calibration Report, and Certificate of Calibration provided

Talk to an expert

Speak with one of our scientists or experts at Droplet Measurement Technologies today to discover solutions that can power your research.

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