Calibration of an instrument is the process of determining its accuracy. The process involves obtaining a reading from the instrument and measuring its variation from the reading obtained from a standard instrument. Calibration of an instrument also involves adjusting its precision and accuracy so that its readings come in accordance with the established standard.

What is Equipment Calibration?

Calibration of equipment needs to be carried out on a regular basis. This is because instruments tend to deviate owing to hard operating conditions, mechanical shocks or exposure to extreme temperature or pressure. Frequency of calibration would depend on the tolerance level. When the objective of the measurement is critical calibration would need to be carried out more frequently and with great accuracy.

To assure accuracy in instrument calibration, it is vital to ensure that each component of the measuring instrument is conforming to its specified standard. Regular equipment calibration carried out in a set format helps you obtain valid data and operate in a safe working environment.

Types of Calibration

Instrument calibration can be carried out on different types of instruments across sectors. Discussed here are some of most frequently performed types of calibration services.

Pressure Calibration

This is one of the most frequently performed types of equipment calibration. Under pressure calibration service gas and hydraulic pressure are typically measured across a variety of sectors. Various types of pressure balances and calibrators along with a number of pressure gages are used for carrying out pressure calibration. For the purpose of pressure calibration, it is vital that ISO 17025 UKAS accreditation and national standards be adhered to when performing pressure calibration. Pressure instruments that are frequently calibrated include:

  • Analogue Pressure Gauges
  • Barometers
  • Digital Indicators
  • Digital Pressure Gauges
  • Test Gauges
  • Transmitters

Temperature Calibration

Temperature calibration is carried out in all processes where temperature readings play a critical role. Temperature calibration is carried out in a controlled environment. State-of-the-art electrical and mechanical thermometers are available that can help in the process of temperature calibration. Temperature measuring equipments that require calibration on a periodic basis include:

  • Chambers/Furnaces
  • Data Acquisition Systems
  • Dial Thermometers
  • Infrared Meters
  • PRTs and Thermistors
  • Thermal Cameras
  • Thermometers/Thermocouples
  • Weather Stations

Flow Calibration

Flow calibration services needs to be carried out on a routine basis for flow meters that check product or feedstock quality and quantity, fuel/energy quantity or function in a critical process. The four main types of flow meters that frequently require calibration include:

  • Laminar Flowmeters
  • Rotometers – Gas and Air
  • Thermal Mass Flowmeters
  • Turbine Meters

Pipette Calibration

Pipette calibration is essential for laboratories that frequently make use of this measuring instrument. Various types of pipettes are being used in the laboratories such as single-channel and multi-channel manual pipettes and electronic pipettes. Pipette calibration needs to follow several aspects of calibration process and protocols. When carrying out pipette calibration accuracy and precision of liquid volume, operator training application besides other factors should be carefully considered.

Electrical calibration

Electrical calibration is required for checking the veracity of electrical instruments across a diverse range of industries. Under electrical calibration elements such as current frequency, resistance and voltage are checked. Ensure that calibration process has been carried out under UKAS accredited standards as it is considered the most credible way. Instruments that are frequently sent for electrical calibration include:

  • Clamp Meters
  • Counter timers
  • Data Loggers
  • Electrical meters
  • Insulation Testers
  • Loop Testers
  • Multi-meters
  • Oscilloscopes
  • RCD

Mechanical calibration

Mechanical calibration services are invoked for a range of mechanical instruments. Under this process a number of elements such as mass, force, dimension, angle, volume, flatness, torque and vibration are calibrated in a temperature controlled facility. Some of the most frequently tested instruments for mechanical calibration include:

  • Accelerometers
  • Load Cells & Force Gauges
  • Micrometers, Verniers, Height Gauges
  • Scales/Balances
  • Torque Wrenches & Screwdrivers
  • Weight & Mass Sets


The exact process of equipment calibration shall vary according to the type of instrument, how critical its role is in the operation and standards that are followed for the calibration purpose. Mentioned below is a typical process that needs to be followed for equipment calibration.

  • Attention given to the instrument design: When carrying out calibration, special attention should be given to the design of the instrument which is to be calibrated.
  • Follow instructions: Instructions specified for carrying out equipment calibration should be followed closely. Deviation from instruction or use of wrong calibrator value may result in accuracy.
  • Check tolerance value: Tolerance value of the instrument should be taken in regard. It may be noted that every calibrator has a particular tolerance level this is due to the normal variations in the instrumentation and quality control process. The tolerance level will vary according to several factors including the industry sector and even the country in which the calibration process is to be carried out.
  • Accuracy ratio: Maintaining accuracy ratio is also critical in a calibration process. This describes the accuracy of the test standard in comparison to the accuracy of the instrument which is to be calibrated. Ensuring at least 4:1 accuracy ratio is essential. This suggests that the accuracy of the standard should be at least four times greater that the instrument which is to be calculated.
  • Adhering to standards: Adhering to internationally recognized standards is vital. Hence when calibrating equipment, all standard procedures established under nationally or internationally recognized standards need to be followed.
  • Make uncertainty analysis: Uncertainty analysis is to be taken at the end of the calibration process. This helps to evaluate any factor that may have affected the results of calibration.

Need of Equipment Calibration

Calibration of equipment is not just desirable, it is rather a necessity. All measuring instruments, whether they are used in factories, laboratories or at home, need to be calibrated on a periodic basis to ensure they are offering accurate results. However, in factories and laboratories, measurement results are usually of a critical value. Deviation from accuracy can not only affect productivity but also cause threat to the life of workers. Hence, it is imperative that instrument calibration be carried out carefully and at regular intervals.

What is equipment validation?

Equipment validation comprehensively establishes in a documented way the instrument is working accurately. A validation process offers evidence that the components critically contributing to accurate functioning of the equipment consistently meet the predefined specifications and operational attributes. The process involves keenly identifying and quantifying each constituting element that has a bearing upon the result produced during analytical measurements. Validation is a commercial grade assurance that internal malfunctioning of the equipment will not adversely impact the result’s quality.

Features & Benefits

Validation course is guided by validation protocol. It is a written plan expressing the method of conducting validation. The salient features considered are test parameters, product attributes, production equipment, and decisive stages that define the scope of acceptable test results.

Analytical Methods validation seeks to establish through laboratory tests that the instrument’s performance characteristics conform to the analytical needs of the desired applications.

On-going validation is intended to approve the sanctity of method control activities to conclusively prove that the validation results are authentic.

Prospective validation is undertaken before distribution of a fresh product or equipment manufactured under revised production standards, wherein the revisions have the potential to impact the equipment’s characteristics.

Retrospective validation is aimed at products in the distribution cycle contingent upon collected production, testing and control data.

The integrity tests ensure that the equipment meets the industry and regulatory specifications. The validation is a cost effective way of drastically cutting the time delays involved in launching a new product. It is flexible in the sense that the test can be performed on manufactures’ site or else by simulating the operating environment and conditions with standard samples. Validation elicits tremendous faith in the equipment’s integrity from the targeted consumer segment.

The launch of a product can be significantly delayed due to the time consuming nature of equipment validation. The lack of proper understanding of the regulatory requirements and instrumentation accuracies can further add to the woes. The broad steps that customarily set in motion the validation process can be classified as below:

  • Chalking out detailed validation protocol and developing the project timeline
  • Delimiting the design, user and functional requirements
  • Assessing the risks involved to adopt necessary safeguards
  • Gauging the suitability of the testing environment and operational conditions; and simulating ideal functional conditions if necessary
  • Collecting standards results from a certified, traceable equipment to check against the test samples
  • Execution of test cases and preparation of summary report
  • Defining framework to manage deviations and initiate change control procedures to set right distortion causing components
  • Periodic re-validation.

Specifying the appropriate validation protocols as defined below:

  • Installation Qualification (IQ) involves identifying and checking all the components against the manufacturer’s listing. Documentation of the working environment conditions is done to check their suitability for equipment’s smooth operation.
  • Operation Qualification (OQ) concerns itself with checking every function of the equipment to ensure that they are not deviating from the manufacturer’s specifications. The process calls for extensive use of certified, traceable simulators and standards for verifying the reliable and accurate processing of input parameters.
  • Performance Qualification (PQ) part checks the performance of the equipment through its routine analytical utilization to gauge the conformance to specifications. The readings are tallied against a certified simulator or control standards. Standards exhibiting values similar to the test samples are used. It establishes the appropriateness of the equipment for its designed use.

Need of Equipment Validation

Equipment validation is the hallmark of assurance that certifies the accurate functioning of an instrument under the prescribed range of operating environment and conditions, while steadfastly adhering to the correct operating specifications.

Validation facilitates meeting industry and regulatory standards set down to govern the accuracy of instrumentation. The validation protocol’s format and content can be tailored to comply with the user’s requirements. This further helps in assuring the accuracy level to a high degree.

The non-compliance to GMP or other regulatory body’s requirements may render the instrumentation of a company ineligible for industry use. This can spell significant losses for the company, further underlining the necessity of validation.

Validation generates confidence in the analytical results generated by the equipment. This is critical as even a minor deviation from the standard operating course can bring about failures having the potential of inviting an industrial catastrophe or mishap.

Difference between Calibration & Validation of Equipment

Equipment calibration deals with assessing the accuracy of equipment’s results by measuring the variation against a defined standard to decide upon the relevant correction factors. The equipment is accordingly adjusted to fine tune its performance to tally with accepted standard or specification.

Equipment validation is a documented assurance that each constituent of the equipment is complying with the manufacturer’s specification under defined operating environment and standard. This is pulled off by checking the performance against traceable control standards.


Validation is the recognized means of demonstrating that the functioning of each constituent element of equipment complies with specification. This confers absolute confidence in the analytical measurements. It ensures that the accuracy, reliability and perfection of the equipment are not compromised in any manner. However, to maintain the accuracy of an instrument in use, instrument calibration is needed.