Sudden value jumps in ultrasonic flowmeters when flow is stopped
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Dear all**, I often encounter a situation where gas flow is detected even when the flow of fluid has stopped, while using a certain imported ultrasonic flow meter (four-channel). For example, between 1 a.m. and 9 a.m. on December 7, the ‘cumulative values per hour under standard conditions’ were 45, 200, 233, 517, 1174, and 50 respectively; the instantaneous flow rate in all cases was 83.47 cubic meters per hour, which is equivalent to approximately 5650 cubic meters per hour under standard conditions. For another example, at 8:00 on December 8, an accumulated value of 4.235 cubic meters was recorded for the previous hour. During the shutdown period from November 15 to December 6 (as there are two pipelines, measurement was carried out using the other pipeline during this time; the valves at both the upstream and downstream ends of that pipeline were closed, while after resuming supply the valves at the upstream and downstream ends were not closed – only the inlet valve of the pressure regulation unit was closed), thousands of cubic meters were accumulated almost every day; on November 28, the cumulative amount even reached over 10,000 cubic meters. Additionally, on December 4th, there were approximately 3 negative instantaneous values; all of these volume values were included in the total cumulative amount. So I ask everyone, what exactly causes these fluctuating numbers? It is said that water accumulation and dirt in the probe are to blame, but could this actually lead to an increase in gas volume? Urgent online.
It may not have been assembled strictly in accordance with the requirements, or there is interference in the surroundings. We usually look at trends.
I don’t understand; were these cumulative amounts resulting from a gradual accumulation of low flow rates, or from a single peak in flow rate? Were the inlet and outlet valves closed after the supply was stopped? How far is the valve from the flow meter if it is closed?
Is it inserted into the pipe or installed by being attached to it? This needs to be considered on a case-by-case basis.
It’s inserted into the pipeline; it’s four-channel. It seems that models with two channels, as well as those with 5 or 6 channels, are also produced.
In that case, the probe needs to be removed to check for dirt or other abnormalities; after cleaning it, try installing it back again.
When it is in standby mode, the upstream and downstream valves are closed. Once this circuit is put into use, the upstream and downstream valves are not closed, but the upstream valve of the pressure regulator – that is, the pressure regulation unit connected below the metering skid – is closed.
This post was last edited by yield1120 on 2015-12-22 at 11:01. It’s possible that it is indeed as you said. I took apart two pairs back then, exchanged the ones numbered 1 and 4, and also cleaned the probes; there was oil residue on them, and one of the probe tips even had scratches from being knocked. On the third day after cleaning, I called the station, and they replied that there were no more drops in signal strength. . . . . Inside the pipe, since the ultrasonic cleaner hadn’t been used, I looked inside through the hole and saw that the inner wall was very dirty, covered with uneven oil stains; I inserted a stick into the bottom to stir things around, and a lot of oil came out.