A pH meter is a device (or sometimes a simple paper strip) used in a variety of scientific, commercial and industrial settings to measure the relative acidity or alkalinity of a substance. Applications range from ensuring that soil for growing crops is properly balanced to the testing of tomato juice and other food products to make sure they conform to USDA guidelines. Cost-effective and accurate pH testing is essential in many industries.
Choosing pH Paper
The simplest means of pH testing available is in the form of a simple strip of paper coated with substances that react and change color in the presence of acidic substances. Anyone can use and read a pH paper strip by comparing the color change to colors on a chart. This makes pH paper a great choice in situations in which the pH tester is an unskilled or semi-skilled worker.
Another advantage of pH paper is that it can be used to test solid or semi-solid substances, such as soils; pH meters, on the other hand, are designed primarily for liquids. It is important to keep in mind, however, that paper-based pH evaluations tend to be slightly less accurate than those obtained using a digital meter. Thus, they are only a good choice for applications in which only a low degree of accuracy is necessary.
Choosing an Electronic or Digital pH Meter
Another common pH testing device is an electronic or digital meter. Although these meters are more expensive than disposable paper strips, they produce results with a high degree of accuracy and are therefore essential for applications with a low fault tolerance.
Both electronic and digital pH meters use a probe with an electrode on one end. Hydrogen ions surrounding the tip of the electrode bulb are selectively activated by acidity. The device detects, measures and displays the hydrogen activity as voltage.
The core difference between an electronic and a digital pH meter is the type of device used to detect and measure hydrogen. An electronic meter is essentially a type of signal analyzer that simply measures the voltage at the tip of the probe. A digital meter, on the other hand, tends to be slightly more expensive (and accurate), because it measures and interprets voltage using a computer. This also means that digital meters can have an interactive interface, customizable settings and other special features which enhance their usability.