Analysis of an Electronic Differential Pressure Transmitter Using Strain Gages

Abstract

In this paper, the characteristic features and analysis of the new type electronic differential pressure transmitter developed by the authors are described.
Differential pressure transmitters are used for measurement and control of process variables such as flow rate, pressure or liquid level. The mechanical part of the transmitter described here consists solely of a diaphragm assembly and a cantilever on which strain gages are bonded in a four active arm bridge.
It has no movable pressureproof seals such as sealing pipes or sealing diaphragms, and the influence of line pressure is 0.2% FS of the minimum span at 100kg/cm².
The transmitter has no other springs and levers, so it can be designed with such a high natural frequency as 130c/s.
The dynamic characteristics of differential pressure transmitters have been designed by empirical methods. In this paper, a method of calculation of static and dynamic characteristics of the transmitter is described, and the experimental results show the usefulness of this designing method.
The break point frequency of this transmitter is adjustable in as wide range as 1:100 turning the adjusting screw 8 turns by adoption of a variable damper of a novel design utilizing tapered spiral groove. The response setting is not too sensitive and can be made merely by turning the adjusting screw around a certain number of turns without testing the frequency characteristics each time.