Liquid level controls monitor the fluid level in tanks and similar applications. A liquid level controller opens a valve, activates a pump or sounds an alarm when fluid levels reach a critical point. These controllers keep tanks from running dry or overflowing.

Many liquid level controllers use probes that rely on the conductivity of the liquid to function. A liquid level control system can also use ultrasonic or radio wave technology to monitor fluid levels. Higher-end units provide the operator with extensive feedback regarding the tank's status. When purchasing liquid level controls, consider the following:

1. Prevent a tank from running dry or overflowing with a single-point liquid level control system.

2. Maintain fluid levels between two critical points with a dual-point liquid level control system.

3. Use liquid level controls with leak detectors.

4. Monitor fluid levels at all times with continuous liquid level controls.

Action Steps
The best contacts and resources to help you get it done

Install single-point liquid level control systems

Single-point liquid level control systems often use liquid level control switches to monitor a tank's fluid. This type of liquid level controller senses if the fluid reaches or falls below a specific point and triggers a valve or pump. Single-point liquid level controls can either prevent a tank from running dry or overflowing, but not both.

I recommend: Browse a large inventory of liquid level control switches at Gems Sensors & Controls. The company sells small and large float switches as well as specialty switches. Innovative Components offers liquid level control switches that can be at either the top or bottom of a tank. The liquid level control switch manufacturer can also fabricate custom switches.

Use a two-point liquid level control system

Two-point liquid level control systems prevent a tank from both overflowing and running dry. This type of liquid level control works by setting a probe at a low point and high point and cycling the liquid level control relay between the two probes. The control system makes the necessary adjustments to keep the liquid level between the two critical points.

I recommend: Buy two-point conductive liquid level controls from Allied Plating Supplies. The liquid level control system can be for use with most conductive aqueous applications. Find two-point electronic liquid level controls at Advanced Control Technology. The company can modify the controls to fit your specific application.

Purchase liquid level control technology with leak detection

Liquid level controllers with leak detectors alert the operator that the tank or application is in need of repair. Liquid level control technology ranges from simple leak detectors placed outside a tank and sound an alarm if they get wet to advanced units that provide the operator with exact information about the leak.

I recommend: Order a liquid level controller from Process Technology. The company offers both single-point and two-point control units that are ideal for leak detection. Omron Electronics manufactures a liquid level controller with leak detectors that provide feedback for operations and maintenance.

Detect fluids with continuous liquid level controls

Continuous liquid level controls monitor the fluid's level at all times rather than when it reaches a critical point. Many continuous liquid level control systems have an external device that displays and records fluid levels. Like other liquid level controllers, continuous controllers activate a pump or a valve to adjust critical fluid levels.

I recommend: Contact expo Instruments for standard, modified and custom continuous liquid level control. When existing designs don't work, the company works with customers to design new liquid level control systems. Babbitt International offers a continuous liquid level controller that detects the level of conductive fluids as well as water and oil.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Industrial liquid level controls are available with stainless steel probes that resist corrosion and explosion-proof housing that protects the unit's electronic components.