1. Checking equipment: Since the equipment is not the same as the suppliers and models maybe different, it is necessary to determine the transmitter corresponding to each installation location according to the measuring range, designing installation method and the material required by the process medium.
2. Determine the installation position: Various series of pressure transmitters should be waterproof and dustproof and can be installed in any place. In terms of facilitating daily operation and maintenance, prolonging service life, and ensuring reliability, the installation position has the following requirements:
(1) There is enough working space around, and the distance from any adjacent objects (in any direction) is greater than 0.5m;
(2) There is no serious corrosive gas around;
(3) Free from ambient heat radiation and direct sunlight;
(4) Prevent the output from being disturbed by the vibration of the transmitter and the pressure guiding tube (capillary), the transmitter should be installed in a vibration-free place.
3. The purpose of positive and negative migration of the pressure transmitter is to eliminate the additional error caused by the transmitter to the measurement system.
(1) For example, when the pressure transmitter is installed far below the measurement position, the liquid column formed by the medium entering the pressure tube will always give the transmitter a pressure, making the measurement result of the transmitter become the measured value plus liqud colum value. When the transmitter is positively moved, the start measurement value will equal to the liquid column value, and this effect can be eliminated.
(2) Another example: when the pressure transmitter measures the liquid level, if the negative pressure pipe has a liquid column and always gives the transmitter a pressure, the measurement result of the transmitter becomes the measured value minus the liquid column value. This effect can be eliminated by performing a negative move of the pressure transmitter to make the measurement start value equals to the liquid column value.