Dual piston deadweight testers can greatly enhance a lab?s ability to calibrate wide pressure ranges with the best accuracy. With เพรสเชอร์เกิจ and devices under test (DUTs) which have a broad measuring range, calibration can be quite a lengthy process, as you need to change pistons among test points so as to calibrate its entire range.
However, a dual piston deadweight tester has a higher range piston and low range piston, that allows the technician more flexibility and efficiency in terms of calibration. This advancement comes from decades of innovation and customer interaction to locate a solution for industry needs.
Formula for pressure calculations
Because the Industrial Revolution, high accuracy pressure measurement has been a key requirement in process industries. Pressure measuring instruments like gauges were employed to measure and monitor pressure conditons. They need to be calibrated against instruments of an increased degree of accuracy. Deadweight testers (generally known as pressure balances) are high accuracy instruments found in the calibration of electronic or mechanical pressure instruments. The core component of a deadweight tester is a precisely manufactured piston-cylinder system, onto which a mass load is applied to be able to generate the individual test points in a calibration.
The mass load is proportional to the target pressure, that is achieved through optimally graduated masses. The look of the entire calibration system, along with the precise manufacturing of the piston and cylinder, ensure quality performance with long free-rotation time and low sink rates of the piston. With measurement uncertainties down to 0.002% of reading, deadweight testers are the golden standard in calibration.
A deadweight tester typically consists of a single piston-cylinder system. This requires mass sets to be changed to be able to calibrate multiple or wide measuring ranges. This could turn into a cumbersome process, one which requires many resources. In 1953, the entity today known as DH-Budenberg pioneered the initial dual range piston-cylinder technology with two pistons housed concentrically in a single unit. DH-Budenberg was later acquired by WIKA in 2011. The first design included 1/8 in2 (low pressure) and 1/180 in2 (ruthless) pistons housed in one unit. Using a single mass-set it had been now possible to create two points of equilibrium at 55 bar (low pressure) and 550 bar (ruthless) respectively. This is followed with the release of high pressure variant that could generate pressure upto 1100 bar.
Explanation dual piston design
The initial dual piston design was largely constructed of tool roll, and had an accuracy of 0.03 % of the pressure being measured in the typical model and 0.05 % in the high pressure model. In dual piston calibration, the strain on the low pressure piston is used in the auxiliary piston, that is directly linked to the weight carrier. When correct pressure is obtained, the piston head skirt floats within the low range or ?blue band.? To reach high pressure, the pressure is increased and the low pressure piston rises until a knife-edge on the bottom flange makes a seal contrary to the low pressure cylinder and acts because the high pressure cylinder. Because the low pressure piston does not contribute to the overall weight of the piston and weight carrier, the weight carrier accumulates the auxiliary weight to pay. When correct pressure is achieved, the piston head skirt floats within the high range or ?red band.?
This iconic, patented DH-Budenberg red and blue band piston-cylinder system was re-engineered later with both piston and cylinder components manufactured from tungsten carbide. With the refinements in pressure generation and piston manufacturing processes, dual ranges are now available around 1,400 bar with accuracies right down to 0.006 % of reading.
These developments in dual piston technology made deadweight testers, such as DH-Budenberg?s CPB5800 Hydraulic Pressure Balance, the premier deadweight tester for industrial applications. It really is especially ideal for calibrating a transducer with a wide measuring range, while maintaining the high accuracy for testing and calibration. By using just a single mass set and calibrating instrument, this system can automatically switch between multiple test points of high and low pressure, making pressure calibration seamless, efficient and economical.
Note
More info on our pressure balances can be found on the WIKA website.