Are the on-site calibration results of flowmeters with a liquid medium reliable?
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Many key energy-consuming units installed flow meters back then without having them calibrated, but during inspections and supervision of energy metering, the local quality supervision authorities require that these flow meters be traced back to their origins. The conventional approach is to remove the device for testing, but sometimes the factory cannot stop operating while still needing to make the necessary corrections. In such cases, the local technical department uses external ultrasonic flowmeters on-site for comparison and calibration. But how reliable are the results obtained through this method? I hope the expert can provide an answer.
The accuracy of external clamp-on flowmeters is generally lower than that of flowmeters installed inline. This can only ensure that there won’t be significant errors
1. First, you need to determine whether the precision you require refers to verification precision or calibration precision. For calibration accuracy, it is necessary to have a label and **certification**. The calibration accuracy can be taken to the metrology institute; it’s easy to adjust. 2. Using external ultrasonic devices to calibrate on-site flow meters is theoretically feasible. For external clamping ultrasonic devices, the best precision is offered by brands such as Siemens and E+H, with a maximum accuracy of around 0.5%. However, for general electromagnets, those from companies like Siemens and Yokogawa are used. All can reach 0.3-0.4%. For other contact-type flowmeters, it’s fine if the accuracy is slightly lower.
The credibility of this intangible and invisible thing is known only to them as to how great it is...
As long as the quality supervision department approves it through online quality inspection in the end, that’s fine~~ Hehe
Not to mention the reliability of the external clamp itself, just ten installation workers using ten different methods will result in 10 different outcomes
First of all, here’s the question: is your flow meter used for your own process control/internal accounting, or for trade transactions with other entities? For instruments used in trade handover, they need to be tested before installation; the factory certification is not valid. Moreover, for instruments used in trade handovers, it is generally not necessary to stop operations just because they need to be removed; usually, a tank is designed for storage to provide a buffer. Another **standard: if it is to be used for trade handovers, the accuracy of the gauge must be around 0.3%; in other words, to verify such a gauge, the standard gauge required must have an accuracy of 0.1%. Generally, external ultrasonic gauges do not possess such accuracy. If it is a table used for your process control/internal accounting, whether you conduct **verification is your responsibility; in theory, the quality supervision agency has no role in this. As long as you think it’s accurate, you can use it however you want. I don’t understand what you mean by the “technical department” requiring external ultrasonic devices for comparison.
The accuracy of external clamp-on flowmeters is generally lower than that of flowmeters installed inline. This can only ensure that there won’t be significant errors
Generally, offline calibration should be carried out; in special cases, an external clamp-type ultrasonic flowmeter can be used for comparison, but this is only to verify the approximate accuracy of the online instrument, and it is different from actual calibration.
Do you know how we calibrate it? Electromagnetic flowmeters are used to measure concentrated sulfuric acid; two measurement tanks are constructed using spiral tubes with a diameter of 2 meters. The diameter is measured accurately, and one tank of acid is added every two days. The liquid level is measured with a ruler, allowing for precise calculations, with an accuracy of up to 0.1%.
You can get in touch with me; we can provide on-site calibration services using standard tables, and we have the necessary qualifications for this. You can contact me at qq366931775