LNG Fueling Station Liquid / Vapor Detector

HewTech Electronics LLC has developed an LNG refueling controller to detect the phase-change from Vapor to Liquid for Liquefied Natural Gas (LNG) filling stations or other Cryogenic liquids.


The Model RTS-100 controller monitors a Sensor positioned in the LNG fill line.  The controller provides a RELAY contact change when the Sensor detects Liquid flow.

The Signal represents the absence of Vapor & presence of Liquid LNG at the sensor. The VENT solenoid is CLOSED & the FILL solenoid is OPENED.  Liquid fuel is then routed to the vehicle fuel-tank through the FILL nozzle.

The sensor is manufactured from 1/8″ diameter 304 Stainless Steel.  A Teflon cable provides protection from the harsh environment. The control is contained within an IP54/65 (NEMA4/5) enclosure with a sealed (tinted) cover.  The cover provides a visual indication of the status LED’s and RELAY position at the control location. A 10-amp SPDT RELAY is provided.

Calibration is a one-time operation.  A small screwdriver is used for adjustment while monitoring the STATUS LED’s.  A FAILSAFE mode detects sensor failure or malfunction.

Power is 120VAC @ 3-watts, transformer isolated. The control provides transformer coupled, low-voltage DC power to a grounded sensor. Sensors are available in custom lengths for all applications.

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