I don’t understand why the diameter of the main pipe at the temperature and pressure measurement points on the ammonia pipeline changed from 3 inches to 6 inches!
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As shown in the figure above, the pipeline is the ammonia supply main for the SCR system; I don’t understand why the diameter of this main pipe at the points where temperature and pressure are measured changes from 3 inches to 6 inches! I would like to ask the experts here for advice; thank you!
One should consider the issue of the openings and connections for the field meters and those for remote transmission; all the sampling points are around 1.5 inches in diameter. Another possibility is to consider the stability of the pressure sensing signal and its integrity.
There is mainly a buffer zone and space for installing instruments.
For the requirements regarding the installation and selection of pressure tapping points for instruments, please refer to the \"SHT 3019-2016 Standards for the Design of Instrumentation Piping Systems in the Petrochemical Industry\". It provides a relatively detailed introduction here.
The insertion depth of the thermometer sleeve should ensure that the end of the temperature-sensing element is located in the region sensitive to temperature changes in the medium being measured. When installing inside a pipe, the insertion depth should be at 1/3 to 1/2 of the pipe’s diameter, and it must extend at least 50 mm into the pipe ； (《SH3005》)
It is probably because a certain insertion length is required.
It requires some installation space, but the insertion angle of your thermometer is incorrect
The issue of excessive insertion depth of instruments: generally, at points where temperature and pressure are measured using small-diameter tubes, the diameter changes, as the instrument probe has requirements regarding its insertion depth as well as a minimum distance it must be inserted from the surface
It must meet the insertion depth requirements; moreover, since the thermocouple sheath is relatively thick, it occupies more space around the thin tubing, which affects the flow of the medium inside the tube and increases the resistance.
The instrument is not inserted deep enough; a diameter change is required