If one of the measurement tubes in a mass flow meter becomes blocked, does the indicated value change?
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The E+H 83 series mass flow meters are used for loading measurements, with fuel oil as the medium. Both loading stations are equipped in the same way: a pump and a pipeline are used to deliver the fuel oil for loading. The two stations start loading almost simultaneously on the same day; however, the measurement value for the amount of fuel loaded at one of the stations is twice the actual amount. When both tank trucks start loading, they also finish loading almost at the same time, taking almost identical amounts of time, and the measured values are also very similar. But in reality, one of the stations loads half as much fuel as it should. We suspect that half the flowmeter’s measurement tube is blocked, is that reasonable? Does a clogged measurement tube affect the measurements? Won’t the measured value also be reduced by half?
I haven’t used an E+H flowmeter before; this is likely the case – one of the pressure taps for positive or negative pressure is blocked. You can check that
This post was last edited by zhjw911 on 2022-7-3 08:54. The mass flow meter consists of two parallel measurement tubes; later, it was modified to use a separate unit, and the measurement values returned to normal. Then both level sensors were installed together, and everything has remained normal ever since. So we suspect that the high pressure during individual loading cleared the blocked measuring tube. I’m not sure if it makes sense
Has anyone encountered a similar problem?
I guess you’ve never seen a mass flow meter
It must be the reason mentioned by the original poster. Over a decade ago, we supplied five mass flow meters to a chemical manufacturing company in the Northeast. One of these meters was moved from a propylene processing station to a phenol processing station, and a similar fault occurred there as well – the output value was nearly twice as low. The maintenance staff carried out zero-point calibration and parameter adjustments on site, but no issues were found. I also couldn’t detect any problems when I went to the site at first; it was only later that I noticed a particularly large differential pressure during operation. I assumed that phenol had solidified due to condensation over night and blocked the measuring tube, so I asked the technician to blow steam into the flow meter itself, but this didn’t have any significant effect. After stopping the vehicle, the flow meter was removed, and it was found that a mop head was stuck in one of the measurement tubes. After cleaning it out, the meter was reinstalled on the pipeline, and the fault was resolved.
Thank you for sharing your experience. We consulted the manufacturer’s technical staff, who believe that it’s impossible for one pipe to become blocked, but they are also unable to explain this phenomenon.
This post was last edited by qugd on 2022-7-5 at 17:50. It is entirely possible in the production environment that blockages cause a deviation in the flow of fluid through the dual-tube mass flow meter, resulting in an increase in differential pressure and a decrease in flow rate; however, the flow velocity in the tube that remains unobstructed does not decrease, and may even increase. Due to different signal processing methods and calculations, it is entirely possible to result in false traffic measurements. Some modern flowmeters with digital intelligence features are capable of determining the condition of the measurement tube. Let me show you some pictures of the congestion back then, found in old business trip reports. The fault indicates an error in the oscillation frequency, and the stick of the mop head is still there.