New employee here seeking help regarding flow meters. I just started working, and the experienced employee who used to guide me has left; now there’s no one to assist me
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As the title suggests, I would like to ask everyone: how is the differential pressure determined when selecting a orifice plate flow meter? Is it that one sets a specific differential pressure value, and the manufacturer then calculates the size of the orifice based on that value? (If so, what is a typical value to use?) Are there any rules? Is there some other method? Thank you for sharing your insights
All one needs to do is provide the supplier and manufacturer with the flow rate, pressure, and temperature data that need to be measured. For reference.
I work on selection design, which involves the range of differential pressure transmitters; so I’m not very familiar with this aspect
The differential pressure value calculated from the fluid data
Primarily, it is the process engineering team in the design institute that specifies the flow rate parameters as the basis for calculation; this includes the pipe diameter. The instrumentation team can then calculate the differential pressure, or the manufacturer can do so as well – in either case, formulas are used. The client only needs to provide the flow rate, temperature, pressure, and maximum pressure loss, and the manufacturer can carry out the calculations. The manufacturer determines the orifice size of the orifice plate based on the calculation results.
Hello, I’ve seen information on the relevant calculation formulas; is the differential pressure calculation also related to the size of the opening? Can the pressure difference be calculated just by knowing the most basic parameters such as the inner diameter of the pipe, flow rate, temperature, pressure, and density?
Yes, once the parameters of the medium and those of the pipeline are known, it’s possible to calculate them. For a standard orifice plate, the formula is fixed; anyone who calculates it will get the same result. Moreover, the dimensions and styles of orifice plates are also standardized. As the client, you don’t need to do this calculation; just provide the relevant parameters to the manufacturer, who will then calculate the differential pressure. The manufacturer will prepare a calculation sheet for the orifice plate. However, if standard orifice plates don’t work and custom ones are needed, it is necessary to have the factory do the calculations; different factories produce products that vary.
Just provide the flow rate, pressure, temperature, and properties of the medium; the manufacturer will calculate the orifice plate parameters themselves.
Yes, given the flow rate requirements and pipe diameter, it’s possible to calculate the differential pressure. Of course, the properties of the medium also need to be considered; primarily the Reynolds number and pressure
The calculation sheet for the standard orifice plate is provided by the manufacturer of such plates, but some contents of the design document are filled in based on the parameters of the standard orifice plate supplied by the user. http://yunrun.com.cn/upload/201802/05/201802051406221382.png Calculator:××× Verifier:××× Date: ×× year ×× month ×× day Date: ×× year ×× month ×× day Orifice plate yunrun.com.cn/product/174.html Notes: 1. Design standard for throttling devices: GB/T2624-2006. 2. The data in the blue areas of the standard orifice plate calculation sheet is provided to the customer by the manufacturer of the throttling device; “Rated flow rate” is used to set the parameters of the flow meter ； The range of the differential pressure transmitter used in conjunction with the throttling device is determined by the value of “differential pressure △Pmax” given in the orifice plate design calculation sheet. 3. The data in the yellow area of the standard orifice plate calculation sheet shall be provided by the user unit. 4. The data for the parts whose colors are not indicated in the standard orifice plate calculation sheet are provided by the orifice plate manufacturer. What parameters are required for selecting a standard orifice plate? To ensure the accuracy of standard orifice plates, customers must provide the following parameters when selecting an orifice plate: 1. Description of the purpose of the throttling device. 2. On-site installation method for standard orifice plates. Standard orifice plates are usually installed horizontally or vertically. Manufacturers of standard orifice plates produce the orifice plates (nozzles) according to the installation method specified by the user; the user must not change this installation method at the installation site, to avoid measurement errors. 3. Medium to be tested. It is preferable to provide the composition of the medium, so that orifice plate manufacturers can select appropriate materials to produce throttling elements, thereby preventing corrosion of these elements by the medium due to improper material selection. 4. Specifications, dimensions, and material of process pipelines. Pipe sizes are preferably indicated as “outer diameter × wall thickness in mm”. 5. Operating temperature of the standard orifice plate. 6. Operating pressure of the standard orifice plate. The working pressure is gauge pressure. The user must provide the maximum working pressure, normal working pressure, and minimum working pressure, with units in MPa. 7. Flow rate range of the medium under test. The user needs to provide the maximum operating flow rate, normal operating flow rate, minimum operating flow rate, and the unit of flow. 8. Density under medium operating conditions. 9. Is the standard orifice plate applied in intermittent operating conditions? For example, if a user needs to measure water flow, with a flow rate of 60 tons per hour, but the site where the user operates involves intermittent water supply, then an orifice plate flowmeter should not be used. Otherwise, there will be a significant discrepancy between the accumulated flow over a unit of time and the actual flow rate.
As the title suggests, I would like to ask everyone: how is the differential pressure determined when selecting a orifice plate flow meter? Is it that one sets a specific differential pressure value, and the manufacturer then calculates the size of the orifice based on that value? (If so, what is a typical value to use?) Are there any rules? Answer: Yes, generally a value is chosen, usually around 20–40 kPa; however, this is not absolute. If you already have a transmitter that meets your requirements, then that one can be used. They (the orifice plate manufacturers) will select an orifice plate with an appropriate roundness ratio based on your values. When choosing on your own, pick an integer; if the number you choose makes it difficult to calculate the phase ratio, the manufacturer will contact you by phone. Is there some other method? Answer: Yes, if the value is not specified, simply enter ≤60kPa for that field. The manufacturer will calculate the differential pressure based on the degree of circularity and operating conditions; however… it’s very likely to be 28.995kPa, so be prepared for that.