Installation issues of orifice plate flow meters
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This post was last edited by chenmiao112 on 2019-8-9 at 22:35. I installed pipe orifice flow meters at the steel plant; they are designed for a flow rate of 8.5 standard cubic feet per hour as a typical value, with a maximum of 30 standard cubic feet per hour, and the medium used is propane. It has been installed, but the actual flow rate is 2.3 kg per hour. The EJA110 is used to measure the pressure difference, and its reading is far lower than the actual value on site. I would like to ask everyone what could be causing this phenomenon. They originally installed DN32 swirl turbines, but they did not use instantaneous values; only cumulative values were used, and the accuracy was very poor. What I found out later is that the gas used on site was supplied to the pipes from gas cylinders; the pressure in these cylinders was 3 kilograms, and the net weight of the gas was 30 kilograms. It is known that 600 kg of gas was used at this site over a period of 21 hours. This total amount includes gas used in other sites as well, but the consumption at our installation site is the highest – the medium used is propane, with a density of 1.964; the temperature is around 35 degrees, and the pressure in the pipelines at the site is approximately 1.5 kilograms per square meter. My estimate is as follows: I assume a minimum consumption of 300 kg (the actual consumption will definitely be higher than this value). Based on 21 hours, the consumption rate is 14.29 kg per hour. With a density of 1.964, this corresponds to 7.274 cubic meters per hour. At a pressure of 3 kilograms per square meter, the volume flow rate is 28.81 cubic meters per hour. I’m calculating the maximum amount of 600 kg to be used in total (such a large quantity is unlikely to occur in practical applications). Based on 21 hours, the usage rate is 28.572 kilograms per hour; with a density of 1.964, this corresponds to 14.548 cubic meters per hour. At a pressure of 3 kilograms, the equivalent volume is 57.620 cubic meters per hour. If the two pipes on site are shared equally, then each pipe can have a maximum capacity of 28 cubic meters and a minimum capacity of around 14 cubic meters. Could everyone please help me check if my calculations are correct? Also, please take a look at the description I’ve given of the scene to see if there are any issues that need attention, or if certain aspects of it are inappropriate or unreasonable. Finally, it’s about whether our current flow meter can be used. If differential pressure data is available, how much should be adjusted? Or could you please help point out any errors or unreasonable aspects in this? The flow measurement values I’ve obtained using the orifice plate are much lower than the actual values; what could be the reason for this? Please let me know the cause as well. Thank you very much. Things are a bit chaotic on site; I would appreciate your advice.
Why not consider using a mass flow meter?
I’m a complete beginner and don’t understand what the original poster wrote. I’m upvoting this post in the hope that an expert will appear. I just want to ask the original poster: how can one tell when there is a discrepancy between the reading on the flow meter and the actual flow rate?
The quality was too expensive, so it wasn’t considered at that time. Moreover, when looking back at the site now, we find that it’s not possible to obtain accurate traffic data there; all that’s provided is a figure that allows us to make an approximate estimate. That’s why we chose not to use quality
Domestically produced ones are already very cheap. Accidents or operational difficulties arise due to inaccurate measurement of materials, resulting in even greater losses
1. The orifice plate is selected based on the dimensions calculated for the designed operating conditions; when the actual conditions are close to these designed values, the measurements are relatively accurate. Therefore, the first step is to compare the orifice plate specifications with the calculation documents to determine the extent to which the actual conditions deviate from the designed values； 2. To ensure relative accuracy in measurement, temperature and pressure compensation is required ； 3. If trade settlement is required, it is recommended to choose measuring instruments with higher precision.
It’s too lazy to calculate just by looking at it; it’s better to ask the manufacturer to do the calculation for you.
This post was last edited by cqdfwy on 2019-8-21 09:34. It is necessary to clarify the operating conditions at the flow meter. “(Is the medium propane, with a density of 1.964; the temperature is assumed to be around 35 degrees, and the pipeline pressure on site is around 1.5 kilograms?) Are these the conditions at the flow meter? “Is the density of 1.964” applicable under standard conditions or under operating conditions (at the flow meter, with a temperature of 35°C and a pressure of around 1.5 kg or 3 kg)? Based on the conditions provided by the poster, the orifice flow meter should ensure a measurement range of 14.29–28.572 kg/h (mass flow rate). Using a density of 1.964, the flow rate range is 7.274–14.548 cubic meters per hour. This flow rate range depends on whether the density refers to the standard condition (corresponding to the flow rate range under standard conditions) or the actual operating conditions (corresponding to the flow rate range under operating conditions; the flow rate under standard conditions can then be calculated based on the working pressure of the medium, in absolute terms).
Finally, let’s talk about the solution. A mass flow meter for gases was chosen, as it offers a large range. When it comes to welding with propane in steel mills, one of the biggest problems is that the amount of gas used with one machine is completely different from that used with 10 machines. Therefore, flow meters with a very large range ratio are required for measurement; considering everything, using the mass of gas is the most cost-effective approach