Wednesday | March 21, 2018

TPF Inc.’s Overfill System with Probe

Overfills of liquid asphalt cement (AC) can result in wasted material and serious injury. To help tanker truck drivers and operators at terminals and asphalt plants avoid overfills, TPF Inc. of Cincinnati, Ohio, has introduced the TPF Overfill System with 4TPFB Probe. Here’s how it works.

A 24-inch stainless steel, gas-filled probe is mounted vertically in the tank that is to be monitored. A 2 1/2-inch long sensitive portion, which is welded into 5/8-inch diameter housing at the base of the probe, senses temperature fluctuations as the tank is filled.

As the gas within the tube heats, it expands. Because the volume of gas is held constant in the probe, the pressure inside the system increases when the temperature outside the system increases. The increase of pressure causes a spike in the system that is converted to an electrical output signal. The mechanism at the top of the probe sends the signal to the local programmable logic controller (PLC) where the software interprets the signal.

A rapid change in temperature, which can be caused by liquid’s contact with the probe’s sensitive portion, triggers a cut-off. Using slope intersect technology, the setting of slope can be adjusted to detect an overfill condition within milliseconds.

For more information, contact Chuck Stiens at (800) 903-9968 or

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