What Is a Tensiometer?
A tensiometer is a device that measures the tension of a belt, fiber, or rope. It is also called a tension meter.
Uses of Tensiometers
Tensiometers are used to measure the tension of a string-like object. Tension is the force of internal attraction that occurs when a material is pulled. Each material or product can withstand different tensile forces. If the tension is exceeded, the material cannot withstand the pull and may break, tearing fibers or breaking wires.
Tensiometers are used to measure the tensile strength of wires, ropes, and other products used for hanging applications. In particular, they are used to evaluate copper wire, winch ropes, and elevator wires, which are often used in a pulled state. Tension is a very important property in the evaluation of heavily loaded products.
Tensiometers are also useful in the evaluation of films and bundled ribbons. In these cases, besides being used to evaluate the durability of a product, they are also used to evaluate how much force a product can be pulled during a manufacturing process, such as winding.
Principles of Tensiometers
At its most basic, a tensiometer consists of a string supported at two points and pushed up or down at the center. The force to push up or down is measured as tension.
This type of tensiometer is highly portable and convenient, but it cannot measure the correct tension unless the object to be measured is properly pulled. Since the accuracy of measurement while being held by a human operator is affected by the operator’s body movements and other factors, it is preferable to use a tension meter fixed to a stand.
Pencil tension meters are used to measure the tension of belts used in various types of equipment. The pencil tension meter presses down on the center of the belt stretched between two pulleys, and the tension is calculated by subtracting the amount of belt deflection from the pressing force. Sonic belt tensiometers are also used to measure belt tension, in which a force is applied to the belt and bounced, and the sound waves generated by the belt are read and converted to tension.
Other Information on Tensiometers
1. How to Use a Pencil Tension Meter
This section describes how to measure the belt tension between two pulleys using a pencil tension gauge, the most popular and inexpensive type of tension gauge.
First, the span length is measured. The span length is the length between the centers of the two pulleys. Next, the amount of belt deflection is calculated based on the measured span length. For example, for a V-belt, the relationship between deflection (σ: mm) and span length (L: mm) is: deflection (σ: mm) = 0.016 × span length (L: mm).
Next, to measure the tension, a tensiometer is placed at the center of the span length and pressed down. The pencil tensiometer has a function to register the amount of deflection and subtract it, so the value displayed is the tension.
2. Reliability of the Tensiometer Application
Tensiometer apps have been developed for smartphones with functions similar to those of sonic belt tensiometers. For example, if a belt is under a certain amount of tension, such as a transmission belt in an automobile, it is possible to measure the tension with a smartphone tensiometer application.
The app can be used with V-belts, low-edge belts, timing belts, V-ribbed belts, and flat belts.
However, the accuracy of such a smartphone tensiometer application depends heavily on the sensitivity of the smartphone’s microphone, which measures the sound waves. A high microphone sensitivity increases accuracy, while a low microphone sensitivity decreases accuracy.
For this reason, the smartphone tensiometer application is not suitable for research, business, or other situations where highly accurate tensiometer measurements are required. As noted in the application’s usage notes, measurements taken with a smartphone tensiometer application should be considered as reference values only.