Working Principles of Upstream Regulators
Performance : We can plot the performance of an ideal upstream regulator such that no matter how the accumulation / relief Flow requirement changes, regulator will match that relief Flow required (within it’s capacity limits) with no change in the upstream controlled pressure (p1). This straight line performance becomes the ideal against which one can measure the performance of an actual - real upstream regulator.
Set Point : The constant pressure desired is represented by the set point. But no regulator is ideal. The set point is determined by the initial compression of the regulator spring.
Built Up : The regulator maintains the pressure of the fluid at its inlet. They do not allow the fluid to pass through when the pressure is equal to or less than required pressure. It will open when upstream pressure crosses the ‘set point’ and flow through it is proportional to the rise in pressure above set point. The percentage rise in pressure for rated flow to take place is termed as built-up.
Reset Point : When the inlet pressure reduces, the flow through the regulator drops and the regulator closes tight shut-off when pressure is below the set point. The percentage drop in pressure below set point can be termed as blow down accuracy.
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