Pull to Stop Emergency Stop Button

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I am new to the Upstream Oil and Gas field and noticed most emergency stop buttons have to be pulled to perform a stop. I normally see emergency stop buttons be of a push to actuate a stop. I have been doing some research on this and the only code I can find is the NFPA 79 and if you look in Annex C at the type of equipment covered it's not even close to the gas/oil processing equipment we have on our locations. Most of our locations do not have rotating or moving equipment, the hazard we are dealing with is pressure and hazardous environments such as a risk of fire and explosion. I'm looking for some advice on this to present a case for changing to a push to stop Emergency Stop. We are in the process of getting an NFPA membership so we can ask the same question for clarification. I'm thinking they will recommend a safety evaluation be performed to determine the risk of a pull to stop button. Any help is welcome.
 

kwired

Electron manager
Location
NE Nebraska
I am new to the Upstream Oil and Gas field and noticed most emergency stop buttons have to be pulled to perform a stop. I normally see emergency stop buttons be of a push to actuate a stop. I have been doing some research on this and the only code I can find is the NFPA 79 and if you look in Annex C at the type of equipment covered it's not even close to the gas/oil processing equipment we have on our locations. Most of our locations do not have rotating or moving equipment, the hazard we are dealing with is pressure and hazardous environments such as a risk of fire and explosion. I'm looking for some advice on this to present a case for changing to a push to stop Emergency Stop. We are in the process of getting an NFPA membership so we can ask the same question for clarification. I'm thinking they will recommend a safety evaluation be performed to determine the risk of a pull to stop button. Any help is welcome.
Not going to claim to be an expert in E-stop requirements for any particular application, but typically the push to stop is more of a panic type operator that must be located in key places to stop equipment when something has gone wrong. The stop devices that require pulling to actuate are usually a safety limit type of device that has a cord draped around a safe boundary and if someone gets too close to hazardous conditions, maybe moving parts, they will have put pressure on this cord and it will pull the safety switch and cause shutdown of the equipment. I guess to some extent it is logical that the pull cord can be used as panic activated switch as well, but I kind of doubt any standards that require the push to stop switch recognize that and the two switch types are both required for a specific need. You could have an installation that requires both types controlling same equipment I would think.
 

iwire

Moderator
Staff member
Location
Massachusetts
My only comment is simply that if everyone on site is accustomed to these pull to stop operators changing them now may well be counterproductive.
 

mgookin

Senior Member
Location
Fort Myers, FL
We "pull" a fire alarm and we "push" a fuel station shunt.

I don't have your answer but it would be interesting to discuss.

Can you take a picture of one of these pull to shunt devices?

Are you shutting down a pump? (sounds like you're saying risk is due to over-pressure, fire, etc.)
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I assume they are connected that way to avoid accidental activation of the emergency stop system. A e-stop that you push to initiate the e-stop is often bumped resulting in an accidental activation. Often hinged covers, or even "break glass" devices are added to the push to stop buttons.

I don't see this as an issue, assuming the tag on the button says "pull to stop" and the operators are trained on the method to activate the emergency stop system.
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
Going with what Don is saying about a pull-to-stop possibly preventing accidental emergency stops, are there any hazards or issues if the emergency stop buttons are accidentally activated?
 

gnuuser

Member
Location
Nw.Pa.
I am new to the Upstream Oil and Gas field and noticed most emergency stop buttons have to be pulled to perform a stop. I normally see emergency stop buttons be of a push to actuate a stop. I have been doing some research on this and the only code I can find is the NFPA 79 and if you look in Annex C at the type of equipment covered it's not even close to the gas/oil processing equipment we have on our locations. Most of our locations do not have rotating or moving equipment, the hazard we are dealing with is pressure and hazardous environments such as a risk of fire and explosion. I'm looking for some advice on this to present a case for changing to a push to stop Emergency Stop. We are in the process of getting an NFPA membership so we can ask the same question for clarification. I'm thinking they will recommend a safety evaluation be performed to determine the risk of a pull to stop button. Any help is welcome.

it depends on the application used
our palletizor hoists use a pull cord safety switch that surrounds the perimeter of the hoist exit and push-button e stops on the panels and conveyors.
while the e stop button engages the hoist safety interlock pins and shuts the machine down the pull cord switch does the same but also triggers the alarm in the supervisors office. (the reason being that the supervisor is notified whenever anyone enters the hoist chamber and must have the reason logged)

push-button e stops need to be places in various and numerous locations requiring a lot more conductor, while a pull cord safety switches you will not need as many providing that the pull cable moves freely from any point
 

kwired

Electron manager
Location
NE Nebraska
There are instances where the E-stop must be a push type and possibly even be certain sized head or in a specific location, one thing that comes to mind that usually has such requirements is a E-stop for boiler systems near the entry door to the space the boiler occupies.
 
Ron Potts

Ron Potts

Thanks for all the feedback. By the way this is for a horizontal natural gas/oil well. The ESD stop buttons are red mushroom type, yellow back ground and labeled "Pull for ESD". I feel a lot more comfortable now and I believe the NFPA 79 would not apply in this situation. We are not shutting down any pumps or motors, just control valves to stop the well flow through the process equipment. I do think the intent was to prevent accidental activation. Even though there would be know more danger cause by these getting accidently trip I agree that this could be counter productive if we changed them now that operators have been conditioned. We have approximately 128 different location setup this way already. I just had my team going through a wiring methods review for the hazardous locations and we discovered some other changes we needed to make and thought it might be a good time to change this on future location if it was incorrect.
 

RB1

Senior Member
Why is that a "Tennessee" three-way? I'll have you know sir that we have not reached that level of sophistication, and I demand that you retract that charge this instant! (southern drawl added for effect)
 

kwired

Electron manager
Location
NE Nebraska
Why is that a "Tennessee" three-way? I'll have you know sir that we have not reached that level of sophistication, and I demand that you retract that charge this instant! (southern drawl added for effect)
Maybe that is where the first one was installed;)
 
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