Testing water hardness in a laboratory is a labor-intensive process. It requires measuring, set-up, and chemical handling. Industrial sectors prefer test strips for rapid and accurate evaluation of water quality. They help reduce expenses by ensuring the proper water treatment is used. Consistent data also increases productivity and accuracy.

Test Strips

A hardness test involves pressing a loaded object, such as an indenter or ball, against the material over a specific period. It’s one of the most critical measurements for quality assurance because it determines a material’s strength and durability. Test strips for hardness testers provide a quick and efficient method to assess the hardness of materials by offering a convenient and accurate measurement tool for industrial and laboratory applications.

While hardness testers can be used in many industrial applications, they are essential for food manufacturers, as they ensure that water used for processing meets HACCP standards. This is necessary to prevent contamination that could impact the safety and taste of finished products.

These devices come in a variety of forms, including strips and tablets. They allow users to quickly detect the presence of microbial and chemical contaminants in their samples by comparing the color change of the test pad with those of a chart provided on the packaging. They are easy to use and offer high accuracy and precision. They also reduce the need for multiple instruments, reducing costs in the long run.

Measurement Methods

Hardness testing is a valuable mechanical test used for various applications and plays a significant role in quality assurance and quality control demands across many industries. As a static test method, the hardness tester measures the resistance of materials to permanent deformation, such as bending, scratching, and abrasion.

The hardness tester applies a limited compression force to the material sample, resulting in an indentation on the surface that can be measured and assigned a value. The shape of the indentation will determine the type of hardness tested. Metals require a heavier load to make an easily measurable depression on the surface, while soft materials like thermoplastics require lighter loads.

Several factors influence the accuracy of the test, including the angle between the specimen surface and the axis of the indenter. A tilt of one degree can cause a 5% error in the hardness measurement, so keeping all test surfaces perpendicular to each other during the test is essential.

Measurement Errors

Indentation testing systems such as Brinell, Vickers, and Knoop measure the dimensional characteristics of the indented surfaces of test specimens and plug them into formulas that yield a hardness number. The resulting values reveal a material’s susceptibility to cracking, its ability to withstand impact, and even its degradation due to exposure to environmental constituents like hydrogen sulfide.

The most challenging aspect of hardness testing is the ability to resolve the ends of impressions accurately. It requires the operator to make measurements of the impressions using a high-magnification optical comparator that can detect and precisely define minor, seemingly infinite points.

It’s also critical that the indenter be perfectly perpendicular to the surface of the specimen. One study indicated that a single degree of tilt between the specimen and the axis of the indenter could result in a 5% error. Fortunately, this problem can be reduced by adequately preparing samples and using properly aligned tester components.

Tester Errors

The hardness of a material is measured by pressing a standardized, complex instrument (called an indenter) into the sample for a standardized length of time and with a specific load (force). The deformation created by this test method is converted to a hardness value of a particular scale.

Various materials can undergo this testing, from metals like aluminum and steel to elastomers, rubbers, and plastics. The hardness of these materials can impact their strength, durability, and resistance to corrosion.

Several different types of tester equipment are used. The most common is bench equipment that sits on a work table and displays the test results on a dial (analog models) or a screen (digital models). Portable hardness testers can also be used, often better suited to larger samples than the bench models. Both types of equipment require calibration and accuracy checks. These may be outlined in guidelines and protocols from ISO or other organizations.