Orifice plate flow meter
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Dear experts, I have a question. We purchase steam from an external power plant; the steam outlet pipes at that plant have a diameter of DN800, and orifice flow meters are used there. In our plant, there are four such flow meters, with diameters of DN500/DN600/DN600/DN700 respectively. The total flow rate measured by these four flow meters does not match the total flow rate indicated by the two flow meters at the power plant’s outlet There’s a difference of about 3%. Why is that? Heroes, please help me
With such a large diameter, there is an allowable error in the flow meter itself, in addition to flow losses during transmission. This error should be acceptable
I think this error is acceptable.
The more you divide, the greater the error may be.
This error is normal; to achieve a higher accuracy level, it will be necessary to replace the flow meter with a balanced one
First, orifice plate flowmeters have their own errors; second, steam flowmeters require a temperature and pressure compensation integrator
Orifice plate flow meters generally have an accuracy class of 1.5, with a permissible tolerance of ±1.5%. It is normal for the deviations of four such flow meters to be in the same direction; a difference of 3% falls within the allowable error range.
For flow meters using orifice plates, it’s impossible to get the readings to match those of trade metering devices. Orifice plates are generally used for internal metering in factories; ABB’s Torba tubes are chosen due to their low pressure loss and high accuracy in measurement. It’s just expensive.
This error is acceptable. The typical accuracy of a single throttling device is 1FS. The accuracy of throttling devices for measuring gases is generally 2FS. So several of your sets have an overlapping error of 3%, which is within the acceptable range
This difference is quite good. The meter itself has errors, and there are losses in the transmission pipes; therefore, it’s impossible for the readings at both ends to match exactly. In cases like this, as long as the seller’s flow meter has passed the calibration, there is no reason to raise any objections. First, unless there is an agreement, the measurement is based on the seller’s standards ； Second, even if you use your flow meter as a reference, it must be installed at the inlet of the pipeline. Unless the steam price is increased by several percent and the position of the parts is moved to the pipe outlet.