self actuated pressure regulators

Question

self actuated pressure regulators

pdk1950 (Electrical)

(OP)

4 Aug 18 03:24

we are having two self actuated pressure regulators on LPG Line to plant having inlet pressure of 270psig and set pressure of 14.7 psig.
the capacity of each regulator is 230kg/hr of lpg.however it was learnt that the capacity should have been 315kg/hr of LPG for each regulator.
these regulaors have been procured and installed at site.
now question is how to ensure that these regulators provide 315 kg/hr of LPG in place of 230kg/hr?
or a third regulator in pararllel is the only answer?

georgeverghese (Chemical) · Answer 1 · 2018-08-06 03:26:49

You've got to review the sizing calcs for this regulator and re run them to see if there is sufficient headroom to go from 230kg/hr to 315kg/hr at say no more than 95% of the wide open Cv at the higher flow. The regulator vendor could rerun these calcs for you in 5minutes flat. Am assuming that at 95% of max Cv, set point droop on this PCV is minimal - the supplier would know best. If you're in luck, the supplier would give you a larger size replacement trim off the shelf otherwise.

roydm (Industrial) · Answer 2 · 2018-08-09 21:07:18

You call it a self acting regulator, I interpret that as a simple spring and diaphragm, this type of regulator has significant droop (pressure loss with flow)
You want to increase the flow by 37% I expect that would cause a significant drop in pressure, only the designer of vendor can tell you if it's possible without more detail.

Regulators with a pilot regulator (small regulator controlling a larger valve) tend to have better flow characteristics because it acts similar to a pressure amplifier

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self actuated pressure regulators