问题。

例如，如果一个阀门被迅速关闭，从而完全关闭了管道
那么，管道中的压力就会突然下降到零。
这就产生了一个冲击波，它以声速在介质中逆流传播。
介质中以声速传播，与流动方向相反。冲击波被反射到
冲击波在容器的输出端被反射，跑回阀门的输入端，再次被反射。
如此反复。

冲击波和它在两个方向的反射的叠加导致压力急剧上升。

这种增加的压力被称为压力尖峰。它可以比工作压力高很多倍，从而导致传感器的破坏。

压力传感器可能被压力尖峰损坏。
压力峰值往往不被注意。

解决方案。
额外代码591 - 压力通道中的限制器

限制器被焊接在压力通道中。

限制器只允许压力通过一个受限的
孔口，呈 "之 "字形路径。这就减少了到达传感器膜的压力峰值的能量。
峰值到达传感器膜的能量。

应用提示。

• 这个问题在气体中不会出现，只在液体介质中出现，如水、液压油、饮料等。
•  它通常与阀门和泵有关

注意事项。

• 压力通道可能被粘性介质、钙化或沉积物堵塞
• 测量信号的反应将变得有些缓慢（毫秒）。

Definition:
The absolute pressure pabs is the pressure relative to zero pressure in empty space (vacuum).

The relative pressure prel is the pressure relative to the respective atmospheric pressure pamb (air pressure).

Problem:
The air pressure changes constantly depending on the altitude or weather conditions.
Therefore, depending on the application, the pressure must be measured either relatively or absolutely.

Example absolute pressure: Air pressure measurement

Air pressure measurement is an absolute pressure measurement.
It can be used, for example, for weather forecasting or altitude measurement.

.

The relative pressure transmitter measures the pressure prel (hydrostatic pressure of the liquid column) and converts it into an electrical signal.
If the density of the liquid is known, this signal is a direct measure of the filling level h.

Applications include
Wells, lakes, bodies of water, swimming pools, containers, tanks, heating systems, etc.

Example: Venting a vessel by means of a vacuum pump
Target: Switch off the pump at residual pressure 5 mbar abs

The aim is to switch off the pump at a residual pressure of 5mbar abs. The table shows how this can be done using absolute pressure measurement or relative pressure measurement.
The switching point is only determined constantly with absolute pressure.