What is a Deadweight tester?
Deadweight testers are instruments that are used to calibrate pressure gauges. Calibration using the dead weights method is known to have high accuracy and hence is also called the primary standard for accurate measurement of pressure. This calibration method using dead weights is based on a formula and can be used to calibrate pressure exerted by air or gas (also called pneumatic) and by liquid or oil (also called hydraulic). In this post, we will take a deeper look at dead-weight testers and their use.
Pressure gauges
When a force is exerted on a surface either by liquid or by gas, this is called pressure, and it is calculated as force per unit area. Instruments that can measure this pressure and display it in a standard unit of measurement are called pressure meters or pressure gauges. They are also called Vacuum gauges, which measure pressure values that are below ambient pressure. Pressure gauges are of huge use in various industries like automobile, oil manufacturing, aeronautics, food industry, chemical industry, etc. They have been used in these industries for over a hundred years, and it has been constantly changing and evolving to fit the needs of newer appliances.
Calibration of Pressure Gauges
Pressure gauges, like any other measuring instrument, need constant testing and calibration to ensure that the measurements displayed by the gauge are accurate and error-free. In simple words, calibration is required to ensure that the measuring instruments are doing their job correctly. In this calibration process, a standard device is placed alongside the device under test (DUT) and then, pressure is applied to the device under test until it displays the values that match the standard device.
Calibration of pressure gauges is conducted using the dead weight testers because as mentioned above, it is one of the methods with maximum accuracy. There are various other pressure calibrators also available in the market, but dead weights are the most preferred.
How does the dead-weight tester work?
A dead weight tester is a method of calibration that depends on creating a pressure balance between the device under test and the standard device. In this method, some weights are put on one side of a weight stand, and on the other side, the weight which is to be calibrated is placed. Following this, slowly pressure is applied to the apparatus using a piston until there is a pressure balance that comes to zero or “Dead”. This is the reason for the name “Dead weight tester.”
This calibration is based on the formula:
P= F/A
Pressure = Force/ Area
To be exact, The P refers to the reference pressure in Pascal (Pa), The F refers to the force applied on the piston in Newton (N) and A refers to the effective area in square meters (m2).
Most of the applications that need to be calibrated lie within the pressure range of 0-2500 bar. However, dead weight testers are equipped to measure the pressure of up to 10000 bar. The accuracy of this calibration system is between 0.005% and 0.1%, which is very high. This highly accurate apparatus, however, is also very complex to put together, and it is very important to reach out to the best manufacturers for the apparatus. At Nagman, we manufacture highly sophisticated dead weight testers that come with meters that pick up on the ambient parameters at the time of calibration and also allow for automatic correction on a real-time basis for an even more accurate calibration process.
Using dead weight testers, you can precisely control and measure the pressure of an instrument. This makes it easier and efficient to calibrate pressure meters that have gone through even the most intensive wear and tear. Apart from that, they can also be used to calibrate secondary pressure devices and instruments. They are also known to provide precise and accurate readings when it comes to measuring unknown pressures.
Advantages of Dead Weight Testers
- It can be used to calibrate all types of pressure gauges, such as pressure transmitters and industrial pressure meters.
- They are very easy to use.
- The accuracy levels are very high
- It can be used to calibrate pressures for both fluid and gas
- Very cost-effective solution
- Adjustments can be done on a real-time basis at the time of calibration
Limitations of Dead Weight testers
- Sometimes, the accuracy may be affected due to the friction between the piston and cylinder
- There is an uncertain value of the gravitational constant also involved that can affect the accuracy.
At Nagman, we manufacture deadweight testers that are known to be high class. They have quick stabilization times, and they are also easy and effective when it comes to fine-tuning or making adjustments.
