What type of conduit sleeve is required for a conduit penetration into an unclassified space from a Hazardous Class I Division I space? How do we prevent gases from migrating around (inside and outside) the sleeve into the unclassified space?
To maintain a safe environment in a hazardous location, it is important that conduit systems in the hazardous locations are provided with suitable seals.
The recommended practice for locating sealing fittings in electrical conduit installations is based on the requirements outlined in Article 501-5 of the NEC. Sealing fittings in conduits are to prevent the movements of gases and vapors from a hazardous to a remote hazardous location or from a hazardous to a nonhazardous location and are also to prevent an explosion from traveling from one portion of the conduit system to another portion of the conduit system, thereby reducing build-up of high pressures. When seals are not used, an explosion inside an explosion-proof enclosure will travel rapidly through the conduit system, building up a pressure that could exceed the strength of the conduit.
Without knowing more; the wall has a fire rating and the room has an exhaust system with negative pressure that is alarmed? You can call STI Firestop and discuss the specifics with their engineers including wall construction, rating, and materials in the room. Conduits will need seals. Just curious, does the room have a blowout panel?
Thank you James. I'll give them a call. I don't think the room has a blowout panel. I'm not sure if the room has that kind of exhaust system and I would have to ask the process team. I know about the seals and have an EYS from Crouse Hinds spec'd but I was asking the question in the event that gases from some other part of the classified space besides the conduit become an issue.
ProductSpec can help with that:
Products, Systems or Assemblies
Building or Fire Systems
Search with Specific Parameters
Metallic Pipe, Conduit, or Tubing
and go from there. It isn’t so much that it’s a hazardous location, it’s that the wall has a specific rating. Someone should go back to the design professional and ask him or her to provide the SPECIFIC firestop system that is going to be used for the through-penetration. When I do plan review, I get them to put the specific system on the plans. This way, the inspector doesn't have to worry about it and can just check for compliance with the system that is shown on the approved plans.
Hilti also has approved systems. There are also others.
To answer your query, the gases don't really "migrate" because the annular space is filled and then sealed. Still, this is a consideration of the design engineer of what firestop system is going to be used.
Thanks Nick. I am the designer in this instance and it sounds like I need to coordinate with the architect to determine the rating. Initially in my details I had to fill the annular space around the conduit with permanent concrete grout.
Yes Guillermo, this is true but I was asking about sleeves.
That is correct. But OP isn't asking about seal fittings. Kelley is asking about through-penetrations, which is an entirely different thing.
Kelly is inquiring about the space around the OD of the conduit where it passes through the wall. The hazardous area/room should be under negative pressure, or else the surrounding areas/rooms would also be considered a lower class hazardous location. To build a room that would be classified as a C1/D1 location without some means of vapor control would be almost impossible. I installed many conduits and tray installations through walls and floors of hazardous locations using seal bags to maintain the fire rating in the wall installation. The negative pressure system in the room, along with appropriate alarming and control systems, took care of vapor migration through any penetrations. There are many vendors out there that can help you out with selecting the correct product.
Yes, the first step is to coordinate all this with the architect. Find out what the rating is from the designer, and then let the designer select "whatever" system in order to maintain the same rating. This is an issue that is often overlooked many times. And electricians don't know enough about it. I think Hilti puts on a free class, "Firestop Systems." There are classes available for this.
Who checked off that the question has been "answered?" Guillermo has answered a different question, one that wasn't even asked!
That was me and it was by mistake. I tried to correct but ctrl z isn't apparently a function in this forum.
Control z has saved me many times. I was not aware that it did not work in the forum. No harm done.
Retrieving data ...