2017 Q4 Technical Awareness

API Standard 520 Part 1 9th Edition1 Annex B §B.3.1.2 provides an expression in equation B.13 for the isentropic expansion coefficient in terms of thermodynamic state variables, to be evaluated anywhere along the isentropic path,…

A subcooled yet flashing liquid, in which the vapor pressure is less than the relief pressure yet greater than the superimposed backpressure, represents an occasional non-ideal sizing condition, as the flow is neither fully liquid…

In a previous Fireside Chat, Orifice Flow Calculation Basis, we provided information on the flow of compressible fluids through sharp-edged orifices.  While that topic was primarily geared toward the flow of gases through an orifice…

2017 Q3 Technical Awareness

The 2nd edition of the CCPS Guidelines for Pressure Relief and Effluent Handling1 recommends the work of Darby2 for use in evaluating relief piping systems.  We have already touched on the recommendations regarding roughness factors. …

There are a number of methods available for estimating the capacity of a pressure relief valve for a two-phase relief fluid.1,2  One primary distinction among these methods is the means for representing fluid property behavior,…

In a previous blog, Safe Operating Limits – Part 1, we provided a heuristic for defining the safe operating limits: Obtain the operating envelopes for all modes of operation Identify key limit values for the…

2017 Q2 Technical Awareness

In a previous blog, Safe Operating Limits – Part 1, we provided a heuristic for defining the safe operating limits: Obtain the operating envelopes for all modes of operation Identify key limit values for the…