Now the water pump is used more and more widely, has been applied to many sewage treatment engineering projects has also been a lot of people are familiar with, but two kinds of pressure on the equipment you may explain is not very understanding, here to share with you.
1. The ultimate absolute pressure :
Absolute pressure is the measured internal pressure than the theoretical vacuum how much pressure. It compares the absolute vacuum pressure value of the theoretical state. Due to the limited process, we can not in any case the internal pressure to absolute vacuum 0Pa this value, therefore, the pump vacuum value is higher than the theoretical vacuum value. So when expressed in absolute vacuum, the minus value.
2. The limit of relative pressure :
Relative pressure is the measured internal pressure than atmospheric pressure much lower pressure. Indicates that the actual value of the system pressure is lower than the atmospheric pressure. Since the air inside the container is pumped, the internal pressure is always lower than the outside pressure of the container. So when expressed as relative pressure or pressure, numerical front must take a minus sign, said internal pressure vessel than the external pressure is low.
