An ultrasonic tester, also known as a hardness tester, is used to check how hard or thick something is by touching the probe to a surface; this also can reveal internal flaws. If you are running the probe over the surface of a wall or part, the number of readings per second may be significant in ensuring the device displays the correct thickness measurement. Ultrasonic tester units are sometimes used on parts that are too delicate for more invasive testing methods, so the strength of the waves may be important. Some tester units have a minimum and maximum range, which can be important when dealing with very thin or thick materials. To help work with the thickness measurements, a universal serial bus (USB) port may be helpful in downloading readings to a computer.
If you have a large area to measure for thickness, then one way to accurately measure that area is to run the probe section of the ultrasonic tester over the area's surface. To ensure the measurement is accurate when quickly sweeping over the surface, the number of maximum measurements per second may be important. For example, if the number of measurements per second is two, then you may have to move very slowly for truly accurate readings; a device with 10 or more readings per second will allow you to move quicker.
One common reason for using an ultrasonic tester is to measure the thickness of very delicate parts. To ensure that parts maintain their integrity, it may be good to check the strength of the waves from the device. Softer waves are usually better for this purpose, though they may not work as well on thicker surfaces. The wave strength is usually displayed as pressure force.
Most ultrasonic tester units have a minimum and maximum thickness that they can measure. For example, if the maximum thickness for a device is 10 inches (25.4 centimeters) but the surface you want to measure is thicker than that, then you most likely will not receive accurate results. The minimum thickness measurement is typically 0.04 inch (1 millimeter), but some specialty devices may be made for thinner surfaces.
An ultrasonic tester is normally capable of storing thickness measurements, but the numbers may not be very effective in the tester unit. If the tester has a USB port, then it should be able to transfer the measurements to a computer, where they can be plugged into programs. This is not necessary for common operations and may only be useful for extensive measurements, though it also may help if the area has varying thicknesses.