Generally choose the pressure table from the following three convenient considerations:
(1) the choice of instrument type: the choice of the type of instrument should be able to meet the requirements of process production and price in two aspects. For example, there is a need for local indication or remote transmission, automatic recording or alarming; measured medium physicochemical properties, such as corrosion, high and low temperature, viscosity, degree of soiling, flammable and explosive of whether to measurement instruments have special requirements, site environmental conditions, such as high temperature, magnetic field and vibration on site installation conditions of instrument type whether have special requirements.
(2) the measurement range of the instrument: the measuring range of the instrument is the range of the lower limit value of the instrument scale to the upper limit value. It shows that the instrument can measure the measured parameters according to the specified precision. For example, when the pressure is measured, the upper limit of the pressure gauge is higher than the maximum value of the maximum pressure in the process production, in order to avoid the overload of the sensing element of the spring tube pressure gauge. In addition, in order to enable the instrument to work reliably, in the choice of instruments, it must be considered to leave enough room for. According to regulations, in the case of the measured pressure is relatively stable, the maximum value should not exceed the pressure meter range of 2/3; measurement of high pressure, fluctuations in the larger pressure, the maximum working pressure should not exceed the range of 3/5.
(3) the choice of instrument accuracy level: the accuracy level of the instrument is determined according to the maximum absolute error allowed in the process production. Generally speaking, the higher the accuracy of the instrument, the more expensive the price, the higher the operation and maintenance requirements. Therefore, the choice should be to meet the requirements of the premise, as far as possible the selection of low accuracy, simple structure, low price and durable pressure gauge.
