Why aren’t there many accurate orifice flow meters available for use in such devices?

Why isn’t anyone answering? How does a change in temperature affect flow measurement?

1. When calculating the differential pressure for orifice plate flow meters, the calculations are always done under ideal conditions； In reality, the conditions on-site vary greatly ； 2. Orifice plates are not calibrated before leaving the factory; they are shipped after being measured with a ruler. 3. Some factories work in a very rough manner, making it difficult to ensure attention to detail. So.......

1. The precision of orifice plates is insufficient; the manufacturing environment in China features extensive management practices, with products being shipped as long as they meet the basic standards, and accuracy is considered satisfactory as long as it’s more or less adequate； 2. The operating conditions on site are not ideal, or the actual driving conditions there differ significantly from those specified in the original design; as a result, the orifice plate cannot provide accurate measurements. For example, the density may differ from the ideal value, pressure changes abnormally, or the conditions required for accurate measurement using an orifice plate are not met at all. 3. Finally, abroad, orifice plates are used in metering flowmeters...:L

Many, mainly by referring to the throttle component specifications based on operating conditions and actual phenomena for analysis

May I ask how to analyze operating conditions? Is it the same for gases as it is for liquids?

First, you need to explain why you think none of them are accurate What is the reference benchmark? If it’s not allowed, what is the error? Then there are the operational conditions issues (such as the parameter range of the actual medium not matching the measurement range of the orifice plate design), design errors, or accuracy problems, etc.

This post was last edited by cqdfwy on 2018-6-14 at 10:18. First, a correction: it’s not that orifice plates are only used for measuring flow rates abroad; they are also used in China. Orifice plates do not make it impossible to measure flow; rather, the methods used for calculating flow vary. In typical measurement designs, a fixed flow coefficient is used for calculations, or compensation is applied only to certain influencing factors ； To achieve accurate measurement, it is necessary to properly compensate for all influencing factors. For example, the natural gas industry makes extensive use of orifice plates for measurement, even in trade transactions. There are many quantities that need to be adjusted. In addition to the need to compensate for normal temperature and pressure variations, it is also necessary to account for the effects of temperature on the dimensions of the orifice plates and measurement pipes in the measuring device, as well as the effects of their service life and the roughness of the pipe walls. Additionally, the composition of the medium itself must also be taken into consideration for compensation purposes ； In addition, there are many intermediate parameters that need to be calculated in real time (such as the Reynolds number, expansibility coefficient, isentropic exponent, supercompressibility factor, relative density coefficient, flow temperature coefficient, discharge coefficient, and so on). The computational workload for these calculations is quite large; therefore, a computer dedicated to calculating flow rates is usually used, known as a flow computer.

I don’t think they’re not working well; each one works fine.

Does the expert flowmeter have a compensation calculation formula?

There are certainly calculation formulas. The problem is that the calculation formulas provided in the standard specifications for mixed gas natural gas involve loads of numbers with exponents, and ordinary people don’t have the ability to use them. Those who work on deriving the mathematical formulas for mixed gas natural gas applications are usually the ones who rely on such research for their livelihoods, so they certainly won’t make these formulas available for free use by others. I want to use his formula to pay him in one way or another. :Lol, money is a great thing. At least so far, I haven’t seen any scholars who are not interested in making money publish research on this topic.