Shutdown/Blow down valve transit time

This is an excellent question, and I think the right way to ask it. I have not recently been a boiler operator, but I remember an old criterion that called for a full opening and closing of the blowdown valve. This would take a few turns of the handwheel, so the whole process might occupy about 10-20 seconds. A specified transit time would be more precise. You might google "steam boiler operation" or "boiler blowdown" and get better information than this old "rule." The best time duration might also depend on chemical testing of the water.

Typically, Emergency Shut down valves (ESDV) shall be in the range of 1.25 to 2 Sec per inch diameter of size and (Safety Blowdown Valves) SBDVs shall be in the range of 0.5 to 1.5 Sec per inch diameter of the size.This value is field adjustable.

Dear gkishorenair

are these values from your experience or there is standard talk about these values? if any what is that standard

Hi

Ussualy at all our industries we keep the blowdown or shutdown valves at Full opening speeds of 2 secs or less.

Depends on the process though,

Regards

Dear Mr. Naveen,

Is it possible to keep the stroke speed at 2 sec or less irrespective of the valve size? Even though SDV's and SBDV's are expected to operate at minimum operating speeds to safeguard the process, a figure of 2sec or less seems too small.

Can you please explain how this is achieved? Does all your ESDV's and SBDV's installed in your plant operate at this speed?