Why Calibration and adjustment are two separate things?

We calibrate a weighing device to understand how it behaves but we adjust the device to change its behavior. So to change the behavior of something firstly, we need to find how it is behaving by calibration and then we can adjust the same. It is important to find the device’s behavior before making any changes to its behavior. Therefore, it is reasonable and common to calibrate a weighing device without adjusting it.

A relationship is developed between a known value (standard) and a measured value by the help of calibration.

 Adjusting a balance means that you are intervening in the weighing system, to make sure that the display is set to show the correct nominal value. And Calibration, on the other hand you are testing whether the display is correct and documenting any deviation.

 For all units of measurement, there are some standards established as the basis for a particular unit.  In the context of weighing devices, standard come in the form of Test Weights. The Test Weight is only classified as checking equipment if it has relevant proof of accuracy.  The Test Weight has a certified value and the weighing device is supposed to indicate a value of Test Weight once it is placed upon the weighing device’s receptor. This is how we understand the behavior of the weighing device by calibration using Test Weight of certified value.

 We find a relationship between the certified value of Test Weight and the value indicated by the weighing device and finally we can also make analysis on the behavioral aspects of the weighing device.

Selection of appropriate Test Weight is very necessary for your balance. A balance can never be more accurate than the Test Weight used to adjust it, it depends on its tolerance. Accuracy of the Test Weight should correspond to the readout of the balance, rather than something better. SWPI’s Cast Iron Test Weights are intended for use in the Verification or Calibration of Weights and for use with weighing instruments of medium accuracy class or ordinary class. They are manufactured from high quality cast iron and are free of cracks and pit. 

The proper selection of an appropriate Test Weights involve knowing their proper permissible error limit, which are already set according to the OIML standards according to their class. Test Weights manufacturing as per OIML Recommendation R-111 is our specialty. Shanker Wire Products Industries (SWPI) manufactures exclusively Test Weights since 1961.

The surface quality of the Test Weights also plays an important role in the calibration of the balance. The bottom surface of Test Weight should be perfectly levelled so that it touches the receptor in its totality. SWPI’s Test Weight are well known for its Test Weight with satisfactory surface quality which ensures the accurate calibration of the weighing device.

Adjustment is not calibration. You can calibrate a measurement device without adjusting it. Calibration is developing an understanding of a measurement device. Calibration should include the determination of the measurement uncertainty to enhance the understanding of the measuring device.

To enquire about our Calibrated Test Weights follow the link: https://www.weights-swpi.com/contact/

OIML Systems

Basic and MAA Certificates registered


Information: www.oiml.org section “OIML Systems”

The OIML Basic Certificate System The OIML Basic Certificate System for Measuring Instruments was introduced in 1991 to facilitate administrative procedures and lower the costs associated with the international trade of measuring instruments subject to legal requirements. The System, which was initially called the “OIML Certificate System”, is now called the “OIML Basic Certificate System”. The aim is for “OIML Basic Certificates of Conformity” to be clearly distinguished from “OIML MAA Certificates”. The System provides the possibility for manufacturers to obtain an OIML Basic Certificate and an OIML Basic Evaluation Report (called “Test Report” in the appropriate OIML Recommendations) indicating that a given instrument type complies with the requirements of the relevant OIML International Recommendation. An OIML Recommendation can automatically be included within the System as soon as all the parts – including the Evaluation Report Format – have been published. Consequently, OIML Issuing Authorities may issue OIML Certificates for the relevant category from the date on which the Evaluation Report Format was published; this date is now given in the column entitled “Uploaded” on the Publications Page. Other information on the System, particularly concerning the rules and conditions for the application, issue, and use of OIML Certificates, may be found in OIML Publication B 3 OIML Basic Certificate System for OIML Type Evaluation of Measuring Instruments (Edition 2011) which may be downloaded from the Publications page of the OIML web site.
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Magazine: “Weights & The Society” Volume: 06 & Issue No.: 1

Logo of SWPI    Magazine: Weights & The Society (Volume: 06  & Issue No.: 1)High Denominational Weights

           Published by Shanker Wire Products Industries




“Legal Metrology – Achievements of India and what it can offer to others.”

Article by:

Sri P.A Krishnamurthy,

Former Director, Legal Metrology, Government of India.      


The field of ‘Legal Metrology’ or Weights and Measures’ as is known in the common parlance, is the field where measurements are regulated by Government laws for the benefit of all stakeholders. The main object of such regulation is to ensure standardized procedures for calibration acceptable to all stakeholders, transparency in the whole procedure, and accountability of the measurement results. Continue reading “Magazine: “Weights & The Society” Volume: 06 & Issue No.: 1″