Calibration

US Navy 040830-N-4565G-002 Fireman Joshua Morgan, of Waco, Texas, calibrates an Engineering pressure gage

US Navy 040829-N-7884F-006 Machinist Mate 2nd Class Frank Cundiff completes calibration testing on pressure gauges using the 3666C auto pressure calibrator

F18NARack

Avery postal scale

Utube

Calibration is the process of configuring an instrument to provide a result for a sample within an acceptable range. Eliminating or minimizing factors that cause inaccurate measurements is a fundamental aspect of instrumentation design. Although the exact procedure may vary from one instrument to another, the process generally involves using the instrument to measure values of a known standard, and adjusting the instrument to match or be within a defined range of those values. Calibration is essential in various fields, including manufacturing, scientific research, and medicine, ensuring that instruments measure accurately and consistently.

Overview

Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device. The device with the known or assigned correctness is called the standard. The second device is the unit under test, the instrument being calibrated.

Importance

The importance of calibration cannot be overstated. It ensures that instruments and measuring devices produce accurate and repeatable results, which is crucial in maintaining quality control in manufacturing, ensuring compliance with regulations, and enhancing safety in various industries. In medicine, for example, the calibration of medical instruments can be the difference between an accurate diagnosis and a potentially harmful error.

Types of Calibration

Calibration can be broadly classified into two types:

1. Physical Calibration: This involves physical measurements such as temperature, pressure, or volume. Instruments like thermometers, pressure gauges, and pipettes fall under this category.

2. Electrical Calibration: This involves the calibration of electrical parameters such as voltage, current, or resistance. Instruments like multimeters and oscilloscopes are examples of devices that require electrical calibration.

Calibration Process

The calibration process typically involves several steps:

1. Identification: Determining which instruments require calibration and the frequency of calibration.

2. Standard Selection: Choosing appropriate standards against which the instrument will be calibrated. These standards should be more accurate than the instrument being calibrated.

3. Comparison: Measuring a known standard with the instrument and comparing the results with the actual value of the standard.

4. Adjustment: Adjusting the instrument to minimize any discrepancies between the measured values and the known values.

5. Documentation: Recording the calibration process, including the before and after readings, adjustments made, and the date of calibration.

Calibration Frequency

The frequency of calibration depends on several factors, including the manufacturer’s recommendations, the frequency of use, the importance of the measurements being taken, and the environmental conditions to which the instrument is subjected. Regular calibration is necessary to ensure ongoing accuracy.

Calibration Standards

Calibration standards are defined by various international bodies, such as the International Organization for Standardization (ISO) and the National Institute of Standards and Technology (NIST) in the United States. These organizations provide guidelines and specifications for calibration procedures and standards.

Conclusion

Calibration is a critical process in ensuring the accuracy and reliability of measuring instruments across various industries. By adhering to established standards and regular calibration schedules, organizations can maintain the integrity of their measurements, comply with regulatory requirements, and ensure the safety and quality of their products and services.

Calibration Resources
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