Hazardous location door safety interlock

I have a similar application, but mine is in a hazardous location. Thus far I'm coming up empty for solutions. The client would like to lock some commercial steel entry doors into a small building, which is C1 Div 1 Group D inside. Outside the door is Class 1 Div 2. I've tried mag locks, all the way down to locking guard door switches, and have yet to find anything that is even rated for Class 1 Div 2. Is there no such thing as a locked guard door in a hazardous environment? Any suggestions for solutions are welcome.

I found this when I googled door locks + hazardous location

http://www.couriondoors.com/Parts Courion X Interlocks.html

The client would like to lock some commercial steel entry doors into a small building, which is C1 Div 1 Group D inside. Outside the door is Class 1 Div 2.

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Some distance outside from the door, there has to be a non-hazardous "normal" area where regular old safety switches could be used. In the old days I was taught to move every electrical device possible to the outside of the hazardous areas. Some things can be moved, others can't. Sometimes another perimeter fence can be set up on the boundary of the Division 2 area, and the safety entry locks placed on a gate in that fence.

I still remmeber the entrance to the TNT production facility at Radford Virginia. You walked through a series of gates in a tunnel through a berm, each one having a higher probability that you would be killed in case something went wrong with the TNT reactor. That was a hazardous area, all right, but not a Class 1, Division 1!

Lancie1 said:

Some distance outside from the door, there has to be a non-hazardous "normal" area where regular old safety switches could be used. In the old days I was taught to move every electrical device possible to the outside of the hazardous areas. Some things can be moved, others can't. Sometimes another perimeter fence can be set up on the boundary of the Division 2 area, and the safety entry locks placed on a gate in that fence.

I still remmeber the entrance to the TNT production facility at Radford Virginia. You walked through a series of gates in a tunnel through a berm, each one having a higher probability that you would be killed in case something went wrong with the TNT reactor. That was a hazardous area, all right, but not a Class 1, Division 1!

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Lancie, under normal circumstances you are correct. However, my classification bubble is Class 1 Div 1 on one side of the door, Class 1 Div 2 outside, with the Div 2 bubble extending 10 feet from the doorway. The problem here is not with sensory devices, it is with a LOCKING device. It's not practical to lock the door from over 10 feet away. I have door position switches right on the door installed via I.S. wiring method, but I'm struggling to find something that is I.S. or explosion proof to physically lock the door. Right now the best solution we are coming up with is a custom pneumatic locking mechanism. I called the company indicated in the first response, and will be speaking with them on Monday as their technical person was out for the weekend already. Choices really are limited, I presume because of the point you brought up. When possible, the guard is simply moved out of the bubble.

It's not practical to lock the door from over 10 feet away.

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I know. You have to "think outside the box" on this one. My proposed solution is to effectively move the "door" 10 feet away. In other words, move the lock to a friendler environment by installing a fence around the Division 2 area.

If you had a fence extending around that 10-foot bubble, and you put a normal-area safety lock on the fence (preventing access to both Division 2 and Division 1 areas), would you still need a lock on the doors, or could they just have a latch? If so, disregard my comments. Otherwise, this is often a solution for areas where rated equipment is hard to find. A section of chain-link fencing is often cheaper than high-money hazardouss-area safety switches.

I've read this thread a couple of times now and I keep wondering what is the real intent of the lock? Is it to keep honest people out - possible to open with moderate force - or would heavy equipment be required?

If you are talking about the moderate force application, I would think a pneumatic cylinder could drive a bar in and out of a slot. The tubing to and the cylinder itself could be then be enclosed to prevent tampering. The controls for the actuator could then be located remotely.

Do the locks need to be on the inside the building (making it really difficult in the event of a failure while locked) or can they be on the outside of the doors?

Steve

I assume, because you said entry door that this is a regularly occupied work area. If so your gonna need a crashbar or other OSHA approved quick open door release on the inside of the door no matter the security clerance. I have worked in C1D1 D and C locations for many years and all the doors I have seen have crashbars on them so I know there out there. I will try to get a manufacture for you soon.

Check out Fortress "trapped key"

http://www.fortressinterlocks.com/

The conclusion

Jim asked that I update the post with the conclusion.

While several options were available, the budget eliminated most of them, including building an external fence that is protected, effectively moving the lock outside of the classified bubble.

We did find a fully pneumatic door actuator that we could control to be closed, and use that as the locking mechanism, but we went with the K.I.S.S. method.

Talbot mentioned the Fortress mechanical lock system. We pitched that to the client, and they approved, so essentially their lock will be a trapped key system, with the key that enables testing in the classified area to commence being in a GP location. While not exactly cheap, their stuff seems well built and very industrial. They've now begun considering them for access/security/safety of their gated robotics systems as well.

Had they not approved of this, we had planned to custom design a pneumatic "shot pin" type of lock, which basically would operate like a pneumatically actuated deadbolt. The Fortress solution I think is the cleanest.

Thanks to all for the suggestions. This was a good challenge.

Russ