The main types of liquid sensors are among a larger family of sensors called level sensors, which apply to both fluids and dry products, like powders. Liquid level sensors either detect fluid levels or locate levels at which two liquids of unlike densities meet. However, there are also fluid temperature sensors, which function differently and serve much different purposes.

Continuous fluid level sensors detect and read out the fluid level in a tank or vessel continuously, like an automobile's gas gauge. Point or multi-point fluid level sensors signal an alert when certain levels are reached, usually an extreme low, as with brake fluid level sensors. Combining these two types can serve even more applications.

Manufacturers sell fluid sensors in three different configurations:

1. Sensors alone do not include displays, but do produce an output for interface with controllers and the like. These may work along with switches.

2. Sensor systems include displays and usually function as continuous level gauges.

3. Sensor transmitters transmit data by way of a current loop.

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

Buy industrial fluid level sensors

Fluid level sensors operate via a range of mechanisms. For instance, there is the optical fluid sensor and the air bubble sensor, as well as sensors that operate by differential pressure, electrical resistance and a number of other principles. You should also look for various options, like mounting style and the measurement range.

I recommend: A common type of fluid level sensor is the float, which you can find at Chicago Sensor in low-level, adjustable and multi-point varieties. Omega also has floats, including a transmitter type, as well as ultrasonic transmitters and many other liquid sensors.

Buy auto fluid level and temperature sensors

If you are a car enthusiast who drives hard, you may not have all the displays you want in your car, especially a transmission temp gauge. Or maybe you want to replace a broken gauge yourself. In either case, you are in the market for auto fluid sensors and gauges.

I recommend: ThePartsBin.com carries a transmission temperature gauge to help you prevent expensive damage to your tranny. Additionally, brake fluid level sensors are just one of many auto assemblies sold at Ark-Les. Don't forget to check out Delphi, though. They have a huge selection of manufacturer's sensing products, and also provide resources for after market equipment. They cover personal as well as commercial vehicles.

Buy a fluid temperature sensor or a fluid pressure sensor

Besides fluid levels, especially in industrial settings, fluid temperature and pressure are of interest.

I recommend: Advanced Control Technology, Inc. covers it all. Besides level floats and controls, they have fluid pressure sensors and fluid temperature switches. Another source for pressure sensors is Honeywell. They sell both low cost transducers and specialty items.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Many fluid sensors link to controls and displays, which are either analog or digital. However, there are also computer controlled fluid sensors.