How to select the differential pressure value for orifice plate flow meters

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This post was last edited by tiandiyi*an on 2018-4-12 at 14:50. How should the differential pressure value for a orifice plate flow meter be selected? What should it be set to? It is related to many factors, such as uncertainty and the straight sections before and after the device; therefore, when calculating the orifice diameter for orifice flow meters and V-cone flow meters, it is absolutely not advisable to arbitrarily choose a high differential pressure – instead, various relevant factors must be taken into consideration. Manufacturers of flow throttling devices are aware that when calculating the orifice diameter for such devices as orifice plate flow meters based on field parameters, an issue arises: how to determine the maximum differential pressure value for the differential pressure transmitter? In our normal production process, we cannot simply advise our customers to choose a large differential pressure value; we must truly be responsible for our customers as well as for the company. 1. When the differential pressure is high, the β value decreases, and a lower minimum Reynolds number is recommended for use. As a result, the actual Reynolds number can be much higher than the recommended value; this causes the flow coefficient to stabilize, thereby improving the measurement accuracy. 2. When the differential pressure is high, the minimum required straight pipe section can be shorter. Given this characteristic, for orifice plate flowmeters, taking various economic factors into account, the orifice size that results in the greatest differential pressure should be chosen ； The V-cone flowmeter is relatively better in this regard; when the fluid in use is a Newtonian fluid, the requirements for straight sections in such flowmeters are relatively low, and even if these sections are shorter, it isn’t a problem. As for differential pressure transmitters, those with higher differential pressures are more stable than those with lower differential pressures. What has been described above focuses mainly on the advantages of using a large pressure difference, but in many cases, once development reaches a certain level, it will inevitably bring about certain disadvantages. Those familiar with the manufacturing processes of orifice plate flow meters and V-cone flow meters know that when an excessively large differential pressure is used, the direct consequence is that the opening size becomes very small; as a result, the pressure loss is also high. Orifice plate flow meters already have high pressure losses, and if this factor is added on top of that, the costs incurred due to such pressure losses for the entire process system can be quite significant ； Compared to the V-cone flowmeter, it is slightly more moderate.