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HLS Series Level Sensor by Hayward Flow Control

Accurate and continuous level measurement from inside of a liquid filled vessel is critical for both process control & inventory management.

Additionally, ground-level displays of liquid level in a vessel are an especially important worker safety consideration when vessels are located in difficult to access or hazardous area.

There are many different types of level sensor technologies available today. Important considerations when selecting a level measurement device are accuracy, reliability, ease of installation, and overall cost. Of the options available, hydrostatic pressure is a long-proven technology that provides a highly accurate liquid level measurement.

Hydrostatic pressure is the pressure at a given point within a vertical column of fluid due to gravitational force and depends on the specific gravity of the fluid. Pure water has a specific gravity of 1. It requires 2.3 feet of vertical water column to generate 1 PSIG pressure; 10 PSIG of water would equal 23 vertical feet. By contrast, 98% sulfuric acid has a specific gravity of 1.835. Hydrostatic pressure of 10 PSIG of would equal 12.6 vertical feet.

With a hydrostatic sensor, pressure against the sensing element is converted to an analog 4-20mA signal, then scaled by a transmitter to display a level measurement. 

Hydrostatic level sensors are ideal for continuous measurement in applications that may have foaming, surface turbulence or vapors. The sensor is positioned at the bottom of a vessel, often secured by a ceramic weight, and suspended by the sensor cable which is wired back to a ground-level display or transmitter. Often, the signal is further directed to a control room for remote monitoring & process control.

Several common applications ideal for a hydrostatic level sensor include: sodium hypochlorite storage tanks at a generation facility or municipal treatment plant; sulfuric acid storage tanks used in leaching operations in a metals mining process; or a water storage & distribution tank in an aquatic facility.  

The HLS Series level sensor employs advanced sensor technology to ensure highly accurate and repeatable measurements in a wide range of corrosive liquid applications.

The HLS Series level sensor by Hayward Flow Control is designed with an all-CPVC corrosion resistant body, alumina ceramic diaphragm, and triple-sealed FPM or EPDM o-rings. Accuracy of the sensor is +/- .25% of full scale, with a measurement range of 0-15’ or 0-33’. The cable is FEP coated, and comes in either 30’ or 50’ lengths. Custom lengths of up to 1000’ are also available.

The HLS sensor is 10-35 VDC powered, sourced from the HLST transmitter. The HLST Transmitter is 100 – 240 VAC powered & comes with a NEMA 4X display and an optional NEMA 4X enclosure. The HLST provides a configurable, multi-color LCD display; dual-channel inputs; programmable dual relays; & analog 4-20 mA outputs.

For more information, contact Hayward Flow Control at 1.888.429.4635 or visit us at

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Hayward Flow Control, a division of Hayward Industries, is a leading U.S. manufacturer of industrial thermoplastic valves, actuation and controls, instrumentation, filters, strainers, corrosion resistant pumps, bulkhead fittings and tank accessories, for use in water...

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