If yes, what is the doc name? I have checked this and come to realise that it is the discharge co-efficient that produces the different results. Papa, PE. The Reynolds number can be calculated using Equations 9. In my experience, the difference is greatest in the smaller sizes. TD2K, thanks for the response. Pragmatic and market forces made it more efficient for even a large, industrial general contractor to focus regionally. So, what do you do?

### Technical Information Seetru Limited

This figure is often derated by further multiplying it by a safety factorto give a derated coefficient of discharge. Derated coefficient of discharge is termed Kdr. Theoretical capacity correction factor for subcritical flow. –. Kd. Coefficient of discharge a.

–. Kdr.

## Safety Valve Sizing

Certified derated coefficient of discharge (K. Per ASME, the actual capacity is derated by 10% which is the capacity you will get using the ASME area and ASME discharge coefficient.

In order to account for this, the valve size must first be established, assuming the fluid is non-viscous.

Promoting, selling, recruiting, coursework and thesis posting is forbidden. Papa, PE. If you are looking at a PSV for a specific client or facility, they typically have their preference and I would use the formulas from the appropriate vendor for your sizing.

This is used to make allowances for high viscosity fluids.

c) theoretical capacity times the certified derated coefficient of discharge. Kdr: Certified derated coefficient of discharge (= measured value x ). [Lift type: (ALH: ) Full bore type: ].

Video: Derated coefficient of discharge To Determine the Hydraulic Coefficients(Cc,Cv & Cd) for Small Circular Orifice

AL・ Series 32A: the API orifice sizes and discharge coefficients are assumed values The certified ASME discharge coefficient is derated by a factor of

I have an article on this in the office where I'm not presently but I'll try to remember the key points but not necessarily the historical explanation how we got to this point.

So, what do you do?

It is not permitted to calculate the capacity of the valve at a lower overpressure than that at which the coefficient of discharge was established. I noticed on this program the the manufacturer uses a de-rating factor which results in an effective discharge coefficient of 0.

You will not get the same capacity using the two sets of data. This choice is determined by the risk of two or more devices failing simultaneously.

In any case, it makes life difficult for me when i do costing and feasibiltiy. Posting Guidelines Promoting, selling, recruiting, coursework and thesis posting is forbidden.

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Learn about these topics and more in Xometry's new e-book. A safety valve must always be sized and able to vent any source of steam so that the pressure within the protected apparatus cannot exceed the maximum allowable accumulated pressure MAAP.