Single-flange differential pressure transmitters for measuring the level of liquids in equipment under pressure
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The equipment is under pressure, and there is only one opening for the level gauge. I would like to ask what would be a good method for measuring the liquid level? Can it be measured with a single flange? A single-flange design is not typically used in equipment operating at atmospheric pressure. If it is necessary to measure pressure in equipment that is under pressure, a pressure tap is required to extract the pressure, but such equipment only has a level gauge opening near its bottom.
Double-flange level gauges should be used for level measurement in pressurized equipment； If a single-flange level gauge is used, a pressure tap must be installed on the negative pressure side to measure the pressure; check whether there is an interface similar to a pressure gauge in the gas phase area at the top of the equipment that can be used for this purpose.
Level measurement is carried out using pressure transmitters, based on the formula pressure = density * level * gravitational acceleration. In the case of pressure vessels, it is necessary to know what the pressure level is. Otherwise, it’s not possible to carry out the measurement
What other level gauges can be used for measurement besides differential pressure transmitters?
If you’re not bothered by the installation hassle, the only option is an electrostatic capacitance level gauge. Install from the bottom, attaching the conductive electrodes from the bottom along the tube wall to the top of the tank. (Installed inside the tank) The electrodes fixed to the tube wall must be covered with ceramic materials to prevent electrical conduction.
Pressure vessels cannot have their liquid level measured using a single flange. When using a differential pressure transmitter to measure the liquid level in a container under pressure, the pressure detected on the positive-pressure side (the lower pressure tapping) is actually the liquid pressure ρgh plus the air pressure acting on the liquid surface ； The pressure inside the container is measured on the negative pressure side when using double flanges ； Then the pressure difference across the two sides is ρgh. And if a single flange is used, the air pressure acting on the liquid level cannot be offset. Only pressure vessels at atmospheric pressure can use a single flange, with the negative pressure side connected to the atmosphere, as the pressure acting on the liquid surface in this case is the ambient atmospheric pressure.
It cannot be measured; the problem can be solved by installing a pressure tap at the outlet at the top of the device
I saw it installed this way in a paper mill: a single flange is used at the bottom of the tank to measure the liquid level
What if the pressure is unstable? It’s fine as long as it’s a container with constant pressure
Apply gas phase pressure to the gas phase outlet pipeline at the top.