Pressure transmitter detects negative pressure
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How can a pressure transmitter be used to measure pressure at -500 Pa, temperature at 200°C, with flue gas as the medium? Which pressure transmitter should be used?
It mainly depends on the temperature tolerance of the sensor in the pressure transmitter. There are high-temperature versions of pressure transmitters; if the pressure or vacuum level being measured is not very high, then a regular transmitter will suffice, but a high-temperature version is necessary in such cases
If there is a pressure tap, a regular pressure transmitter will suffice; there is no need for a high-temperature type, and a smaller range is adequate
I’m also smoke – carbon black smoke. It’s at 200 degrees, with a slight negative pressure of -200 Pa. I’ve been working on this for a year; I’ve just typed for half a day before the connection was lost. I’m too lazy to continue typing
A micro-differential pressure transmitter can be used, with the pressure lead extending to connect to the transmitter. However, care should be taken during use to ensure the integrity of the negative pressure side relative to the atmosphere. Due to the slight negative pressure, even a minor fluctuation in the differential pressure can result in a significant change in the pressure output. I’ve encountered this issue in use: on rainy or snowy days, raindrops and snow block the vents on the negative pressure side that are used to allow air to flow in, resulting in frequent pressure fluctuations. If a larger fan is installed, and unfortunately the vent on the negative pressure side happens to be facing the direction of the wind, this too causes frequent pressure fluctuations. So this device is quite sensitive; it’s best to arrange the vents on the negative pressure side so that they face downward, allowing air to flow in.
I’m using a micro-differential pressure transmitter; if it gets clogged, just blow it out with an instrument air stream.
A Rosemount differential pressure gauge will do; this is the type of gauge we use to measure furnace pressure here. It’s best to place the gauge in a protective enclosure, so as to ensure that negative pressure measurements are not affected by external factors such as wind and rain.