What Is a Pressure Recorder?
A pressure recorder is a device used to measure the pressure of gas or liquid passing through piping, and is used to determine the absolute value of the current pressure or to measure and record changes in pressure over time to detect abnormalities, such as piping leaks.
While the pressure recorder, which records absolute values, is used to determine abnormalities in piping, etc., the manometer, which measures the difference in pressure between two points, is used to measure functions in clean rooms, air conditioning, etc.
Uses of Pressure Recorders
The most popular use of a pressure recorder is to test the tightness of piping. A pressure generating device and a pressure recorder are connected via the piping to be tested, and a substance is supplied to apply a predetermined pressure. The recorded value that remains within the predetermined numerical range for a certain period is judged to be free from leakage of gas or liquid and is considered to pass the test.
The recorded pressure is affected by changes in temperature, etc., and must be corrected. Recently, there are products, mainly digital ones, that output results with temperature correction added.
Principle of Pressure Recorders
There are two major types of pressure recorder: mechanical and electric diaphragm type.
The mechanical pressure recorder has an elastic body (Bourdon tube, chamber bellows) in the device to detect pressure, which is connected to the piping and placed in the flow to rotate the quartz clock according to the intensity of the pressure detected by the elastic body, and by moving the pen arm, the pressure changes over time are recorded.
On the other hand, an electric diaphragm type pressure recorder places a fixed diaphragm in the device, connects it to the piping, applies pressure, and records the changes in pressure by detecting the strain generated in the diaphragm. Since the physical strain of the diaphragm itself is slight, the strain is converted into a change in capacitance, and the change in capacitance generated between the moving and measuring electrodes on the diaphragm is measured, compared with a reference electrode, and recorded by amplifying the electrical signal to make the change easier to understand. The changes are recorded by comparing them with a reference electrode and amplifying the electrical signal to make them easier to understand. When the sensing section of the device is open to the atmosphere, the gauge pressure is recorded; when kept in a vacuum, the absolute value of the pressure can be recorded.