ASME orifice plate XLSM calculation program

Download it and study it; thank you for your effort

In fact, the calculation formula for orifice plates is quite simple; what’s most important is the determination of the material properties of the medium, as well as its density at certain temperatures and pressures. Commercial software usually includes a database of such material properties

The master’s content is entirely in English; I used Google Translate throughout: lol

Op, it seems you have expertise in orifice plate calculations. According to the 14M standard in the attachment, it still only applies to subsonic conditions; do you have any good methods for orifice plate calculations in sonic conditions? I previously asked this question on a forum: “As is well known, orifice plates can be used to throttle and reduce pressure, similar to nozzles. The difference is that in nozzles, the maximum flow velocity occurs at the smallest throat diameter, whereas in sharp-orifice throttle plates, the maximum flow velocity – and thus the lowest pressure – occurs behind the orifice. Therefore, when throttling gas, due to the existence of critical pressure, the maximum flow rate at the throat is limited by the speed of sound in the medium, resulting in a limit on the flow rate. As a result, under the same upstream conditions and throat diameter, the flow rate through a nozzle does not increase as the downstream pressure continues to drop. Orifice plates, however, behave differently: once the downstream pressure reaches the speed-of-sound level, the flow rate increases as the pressure continues to decrease. This is different from the behavior of safety valves or nozzles. However, according to HG20570 and other documents, multi-stage orifice plates are used when the downstream pressure falls below the speed-of-sound level, in order to keep each stage of pressure drop within the critical range and avoid choked flow. This approach seems to contradict the actual flow characteristics of orifice plates. My question is: what is the fundamental reason for using multi-stage orifice plates rather than single-stage ones?” How is the flow rate calculated after critical flow occurs during gas throttling using a single-stage orifice plate? ”

For gas throttling, if P2/P1 has reached the conditions for choked flow, it is necessary to consult the process designer: do you want to maintain a constant flow rate (this is what is known as a choked-flow orifice plate, where P2 rises without exceeding the choked-flow pressure ratio, thus keeping the flow rate constant), or are you okay with the flow rate changing as P2 rises (this is what is known as a reduced-pressure orifice plate)? In most cases, the process requirements are for the former approach. That HG standard only allows for grading, ensuring that no level enters a blocked flow state; essentially, it is a design based on multiple stages of pressure reduction. But in reality, for many of our flow-blocking conditions, we require a “stable flow rate,” which HG is unable to address. If you are certain of designing a choked orifice plate but require noise control, then you can design multiple stages, with the final stage being designed for choked flow and the preceding stages designed according to the HG \"pressure division at the edge\" principle. In this case, when P2 at the final stage decreases, the entire system remains in a choked flow state; if it increases and the flow exits the choked state, then due to the reduced flow rate, the preceding stages move away from the choked flow condition, and the entire system operates in a differential pressure flow state. If noise is not controlled, then a first-order blocked flow design is used. The above is my knowledge for your reference. The attachment contains some useful materials; please pay attention to the key points of gas-blocking flow design: t/d0 (plate thickness/opening), and the Cd value for blocking flow is 0.839, which is a value used by many professional software programs. The HG specification was originally written by process engineers. Contradictorily, many organizations classify the flow control orifice plates as part of the instrumentation components, so it was necessary to conduct further research on this matter; it was essentially an ad-hoc approach. Furthermore, the flow accuracy of the orifice plates used for blocking is lower (compared to measuring orifice plates), so it’s sometimes acceptable if the accuracy isn’t very high.

Thank you to the original poster for clarifying this; thanks~~~