|信息来源： 压力变送器 | 2019-04-24 点击量： 1158|
What are the forms of pressure gauge selection?Introduction of Xi'an Huaheng Instrument:Correct selection of instrument types according to product process requirements is an important prerequisite for ensuring normal operation and safe production of instruments.Usually when choosing the type of pressure gauge,the following three requirements should be considered:
(1)Selection according to the requirements of product process in industrial production.For example,whether remote transmission,automatic recording or alarm are needed;
(2)According to the physical and chemical properties(such as corrosiveness,temperature,viscosity,dirty degree,inflammable and explosive properties)of the medium under test,the special requirements for the measuring instruments are selected.
(3)According to the site environmental conditions(such as high temperature,electromagnetic field,vibration and site installation conditions),whether there are special requirements for pressure gauge types and so on.
1.Determining the measuring range of pressure gauge:In order to use the instrument reasonably and economically,the measuring range of the instrument can not be too large,but in order to ensure the measuring accuracy,it is generally advisable that the minimum value of the measured pressure is not less than one third of the full measuring range of the instrument.At the same time,in order to prolong the service life of the elastic element and avoid the permanent deformation of the elastic element due to long-term excessive force,the upper limit value of the pressure gauge should be higher than the maximum value of the measured value(1/2-1/3 of the range),leaving a margin.
2.Selection of pressure gauge accuracy:pressure gauge accuracy is determined according to the maximum measurement error allowed in process production.It can't be considered that the higher the accuracy of the selected instrument,the better.On the premise of meeting the technological requirements,the instrument with lower accuracy and low cost and durability should be selected as far as possible.
Examples of instrument type selection:The outlet pressure of a compressor ranges from 25 to 28 MPa,and the absolute error of measurement should not be greater than 1 MPa.The technology requires on-site observation and alarm at high and low limits.A pressure gauge should be selected correctly and the type,accuracy and measurement range should be pointed out.Requirements are:the measured fluctuating pressure is 25-28 MPa,the absolute error of measurement is less than 1 MPa,in-situ observation,high and low limit alarm.
When choosing the instrument,the fluctuating pressure has a great influence on the life of the instrument.Therefore,the upper limit value of the instrument is:P1=Pmax*2=28*2=56MPa.If the measuring range of the selected pressure gauge is 0-60MPa,the minimum value of the measured pressure is not less than 1/3 of the full range,and the lower limit value also meets the requirements.In addition,according to the requirement of measurement error,it can be calculated that the allowable error of the instrument is 1/60*100%=1.67%.Therefore,the instrument of 1.5 precision level can meet the error requirement.