Differenc between ESDV and Slam Shut off Valve
Differenc between ESDV and Slam Shut off Valve
(OP)
Can someone tell me the difference between an Emergency Shut Down Valve and a Slam Shutoff Valve?
Thank you
Thank you
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Differenc between ESDV and Slam Shut off Valve
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RE: Differenc between ESDV and Slam Shut off Valve
RE: Differenc between ESDV and Slam Shut off Valve
An ESDV might indeed take the form of a slam shut if the service is gas and the only criteria for actuation are overpressure and under-pressure. Apart from that, an ESDV is typically a different style of valve with slower closure speed that can be used in liquid or gas service. Actuation of an ESDV is typically controlled by a signal from SCADA or a PLC, and the criteria for actuation can be a host of things other than pressure.
RE: Differenc between ESDV and Slam Shut off Valve
I think your last point is the key difference--an ESD is part of a site-wide emergency scheme with any number of monitored parameters and criteria while a slam valve is locally controlled based on a very limited number of parameters (usually one and not part of the SCADA system).
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
RE: Differenc between ESDV and Slam Shut off Valve
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Differenc between ESDV and Slam Shut off Valve
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Differenc between ESDV and Slam Shut off Valve
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
RE: Differenc between ESDV and Slam Shut off Valve
The "slam shut" terminology should be "downgraded" in favor of stipulating the desired actuator type and required speed of closure. Then it could be hooked up to whatever system might be available to control it, or not, as the case may be.
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Differenc between ESDV and Slam Shut off Valve
So to sum up:
ESDV: site wide philosophy, safety related, no need to be fast actuating, linked to SCADA and/or Fire and gas/emergency shut down philosophy
Slam shut valve: local impact, process related, fast actuating, no link with SCADA or any PLC (I think there is always an uninterruptible power supply on a solenoid valve to shut the SSV in case of loss of control of the process)
But 2 related questions come to my mind:
1) Is there some regulations dealing with this difference (if possible if you know European regulations, I would take any regulations dealing with this topic though)?
2) Is there a regulation or best practice document dealing with the architecture of an ESDV (by-pass allowed with or without an ESDV on the by-pass, process use of the ESDV allowed if different PLCs are used with a priority for the Safety PLC...)?
Thanks again for your help
RE: Differenc between ESDV and Slam Shut off Valve
I don't think "fast acting" is appropriate for the slam valve either. The issue is mostly "is it part of the safety strategy or part of the process strategy?" not how fast does it operate.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
RE: Differenc between ESDV and Slam Shut off Valve
UPS on a electric solinoid valve would be better used in the reverse position, where loss of power would open the solinoid valve to vent power gas which was holding the ESD open against a spring, rather than the UPS running a motor that closed a valve. Bad idea.
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Differenc between ESDV and Slam Shut off Valve
RE: Differenc between ESDV and Slam Shut off Valve
The few times I've put in a process shut down that wasn't part of an ESD, I used pneumatics from the local process (not the site instrument air or control gas) and pneumatic pilots. When the condition I was concerned about happened the pilot dumped pressure to the slam valve and springs shut it. If I have to bring in power or control gas then the valve and its control are going to be more sophisticated than a "slam valve" (may still just shut, but it will have criteria, ranges, permissives, etc.) instead of "touch the setpoint and slam shut, manually open".
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
RE: Differenc between ESDV and Slam Shut off Valve
If it ain't broke, don't fix it. If it's not safe ... make it that way.
RE: Differenc between ESDV and Slam Shut off Valve
RE: Differenc between ESDV and Slam Shut off Valve
If it ain't broke, don't fix it. If it's not safe ... make it that way.