Compound vacuum pressure meters/gauges are a kind of vacuum measurement instrument which are mainly used to measure the pressure under the standard atmosphere pressure in the vacuum or negative-pressure meter systems.The bourdon tubes in it are used as the pressure elements, which will become elastic expansion due to the pressure of vacuum. The tube expansion causes travelling of the tube end. After the transfer and the amplificaton by the movements and rods, the pointer will indicate readings in the scale of the gauges. Different types of vacuum gauges can be used in various complicated circumstances.
The vacuum pressure gauge helps to determine the total dynamic head (TDH) on the system and with the pressure gauge reading will give an accurate TDH that can be used with the pump curve to determine pumps flow capacity.
This vacuum gauge contains a hermetically sealed, evacuated, thin-walled diaphragm capsule which is located within the instrument. As the vacuum pressure reduces, the capsule bulges. This movement is transferred via a system of levers to a pointer and can then be read off as the pressure on a linear scale.