Light-Pressure Reading Tools

Loads (Pressure)

• "Load" is the term engineers use to describe pressure or force. There are many kinds, from gravity -- pressure exerted toward the center of the earth -- to torsion -- pressure exerted in a twisting motion. Tools designed to read very light pressure may go by a variety of names. Some might be very sensitive scales. Specialized tools are more often called "load cells."

Analog

• Analog load cells are, in effect, any nondigital load cell. Some analog load cells may use watchlike precision mechanics to actuate a dial readout -- much like a micrometer. However, "analog" usually refers to the readout method, not the way in which the load is sensed or transferred to the readout. Analog load cells more often use hydraulics, which are translated in very accurate dial meters.

Digital

• Digital load cells are often mechanical or pneumatic inputs with digital readouts. The conversion is similar to the way a mechanical speedometer is converted into a digital speed readout. Fully digital load cells use a digital transducer. A transducer translates force from one medium to another -- usually for measuring. So a digital transducer is capable of taking load input directly and translating it to a digital display without the need for a mechanical translation as in pneumatic load cells.

Ambient Pressure: Air and Liquid

• There is another type of light-pressure reading device or load cell that's a little different than ones used to measure torsion, shear force or other types of loads where one solid object is exerting pressure on another. Air sensors and liquid sensors measure the ambient pressure of gas or liquid in essentially the same way load cells measure solid forces. A crude example is a tire pressure gauge, though they can be very sensitive such as digital barometers.