In process, chemical and industrial technology, pressure gauges have proven to be particularly effective as an indicator of pressures. With these relatively simple measuring devices, a distinction is generally made between two different types of devices with regard to the measured quantities. Direct pressure gauges usually use the prevailing atmospheric pressure of the environment to define the measurand. Indirect measuring instruments use other physical parameters and effects such as temperature as a basis for determining values. Thus, for example, a physical pressure such as air, gas or a liquid pressure with water and oils can be reliably displayed. Manometers for pressure measurement are offered for different measuring ranges and in different designs. In addition, special measuring instruments such as a slave pointer manometer are used especially for the display of several different measured values.
Pressure gauges with drag pointer as data storage
A very special design is the pressure gauge with slave pointer. This pressure gauge usually has two differently colored hands to display the current pressure values and to display a maximum value. The normal pressure value is displayed via a black pointer and shows the currently prevailing pressure in the system at the reading moment. The red pointer indicates the maximum pressure that has occurred and has been measured up to that point, for example by a pressure surge. The display process is as simple as it is ingeniously solved. Each time the pressure changes, the black pointer will automatically drag the red pointer for the current pressure.
If, for example, a short overpressure occurs, both hands go to this pressure value. If the pressure in the system then returns to normal, the red pointer stops at the maximum value. After a reading, the red pointer and thus the maximum value can usually be reset using a spring button. Here, the red pointer falls back to the black pointer and can again capture and display a further maximum value by the towing process.
At measuring points with very high mechanical vibrations, the use of vibration-damped pointer manometers has proven itself. The partly strong vibrations can influence and change the measuring position of the towing pointer. For this reason, the use of liquid-filled manometers is recommended here. The liquid in the gauge – mostly glycerine – effectively dampens the vibrations, ensuring an accurate and steady indication.