How is liquid oxygen flow rate measured?
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I went to a site today that sells liquid oxygen. 1. Tank height: 12–15 meters. 2. Liquid oxygen temperature: –180 degrees; pressure: 0.8 MPa. 3. The diameter of the main liquid oxygen outlet pipe is DN40. 4. There are 3 individual outlet pipes, each with its own diameter ； DN15, equipped with 3 orifice plate flow meters respectively. 5. 3 flow accumulators were installed. But every time it is measured, the flow integrator and the weighing system give inaccurate results. Requirement: 10–12 minutes, to fill one liquid oxygen tank to 180 kilograms. When the level in the main tank is full, at 12 meters, it fills an 180-kilogram tank. The total amount accumulated by the flow meter is 183 kilograms; the level gauge of the main tank indicates only 1/3 capacity, which is enough to fill a tank with a capacity of 180 kilograms. According to the flow meter… ； The total is 210 kilograms.
Should we calculate the pressure generated by the liquid oxygen level in the tank, in order to provide pressure compensation for the flow meter?
1. The pressure caused by the liquid oxygen level can be ignored; the measurement error of the orifice plate is quite large anyway. If the tank diameter is small, the level difference can also be taken into consideration; the level difference is compared with the cumulative flow value. 2. With the pressure in your tank set at 0.8 MPa, isn’t the self-pressurization mechanism rather slow? 3. This type of measurement is generally based on weighing.
This is why liquid purchased from outside needs to be weighed rather than having its volume measured. Weight is the most accurate measurement method that can be accepted by both buyers and sellers. There are errors in the accuracy of volume measurement as well as in the measurement methods.
Weighing is indeed the best method; the problem is that the seller incurs losses, losses due to vaporization.
This is, relatively speaking, the approach that gains the most acceptance from both buyers and sellers; everything is measured by price – that is what the market is all about. Everything else can be explained. If you want to bother yourself with this nonsense, go ahead: lol
Are you sure the pressure in your main tank is constant? The density of liquid gases changes significantly with pressure.
Emerson mass flow meters are the preferred choice for trade handovers; they are the leaders in the flow meter industry
I agree with the view above; the orifice plate has an error range of 1%-10%, and for trade settlement, it is recommended to use a mass flow meter or weighing method.
There are so many different types of flow rates, and the reason for this is simply that it’s difficult to measure them accurately. Why doesn’t the original poster install an automatic weighing device?