Stainless Rigid Metal Conduit vs. Stainless Tubing
Stainless Rigid Metal Conduit vs. Stainless Tubing
(OP)
If we ever wanted to put a product in a Class 1 Div 1 or 2 Group D area and wanted to use a stainless tube instead of rigid metal conduit for a raceway... is this allowed?
I assume you have to use a rigid metal conduit, but our normal product which houses the wire for a sensor that is screwed on the end uses a 316 stainless tubing that holds up well for heat....
And not that anyone should know this off the top of their heads, but if you run a flex conduit approved for c1 div2 grp D to a nema 7 box... does there have to be a seal on the end of the conduit? or does a nema 7 box have some sort of built in seal already....
I assume you have to use a rigid metal conduit, but our normal product which houses the wire for a sensor that is screwed on the end uses a 316 stainless tubing that holds up well for heat....
And not that anyone should know this off the top of their heads, but if you run a flex conduit approved for c1 div2 grp D to a nema 7 box... does there have to be a seal on the end of the conduit? or does a nema 7 box have some sort of built in seal already....





RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
Off the top of my head, you need a seal whenever something is coming from / to a non-hazardous area to / from a hazardous area. If the flex is coming from a NEMA 7 junction box that is in the hazardous area already and going to another NEMA 7 box in the same area, then I don't think you need a new seal off. But it's been a long time for me... better to check with others.
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RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
does anyone know what or who determines if something is "intrinsically safe" ?
I saw that when doing my research also, and do not know if there is a voltage/current threshold or if an inspector must make that determination? or?
RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
If you are looking at signals that themselves are not IS, you can sometimes use what are called Intrinsically Safe Barriers or Zener Barriers at each end to make the wiring so.
Good place to start since it appears you are unfamiliar with the concept.
http://en.wikipedia.org/wiki/Intrinsic_safety
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RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
Good on ya,
Goober Dave
RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
normally we make the housing for the wire out of 316 stainless for a certain number of feet and then the actual flame rod screws on the end making the connection
I think I got pretty good answers here... but if you can think of anything else to add because of that, please do
Thanks a lot
RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
You're right, I have no good suggestions for you -- can't really picture the area.
I'm not a utility guy, but around most large boilers (such as in hosptitals or campus power plants), the area outside the boiler is not usually classified as hazardous. I'm left wondering what makes your area Class I Div 1 or 2?
Good on ya,
Goober Dave
RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
NFPA Section 70 Article 500 (aka NFPA500?) defines the requirements for explosive environments. Section 500.7E defines Intrinsic Safety.
NFPA 504 defines Intrinsically Safe Systems
UL White Book (2008) defines explosive environments (references NFPA 70 Articles 505 and 506, ANSI/UL 913.
FM 3610 follows the IEC standards referenced above.
John D
RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
My understanding of the availability of SS raceways may be obsolete, if SS raceways are indeed now available someone please correct me and provide additional info (perhaps a URL for a manufacturer's catalog cut).
I would generally recommend PVC-coated RGS or other similar alternates in such locations where you're currently considering SS conduit/tubing.
Re. jraef's statement that "Tubing has no standing and therefore recognition as an electrical raceway" -- assuming we're talking about Electrical Metallic Tubing (EMT), this *is* defined as a raceway by NEC 358.2, although code does make a distinction between EMT and conduit; EMT is *not* conduit. Other types of tubing (eg, water tubing), clearly are not listed by UL or recognized by NEC as a raceway.
RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
Bill
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RE: Stainless Rigid Metal Conduit vs. Stainless Tubing
http://www.gibsonstainless.com/
It's used in food processing plants all the time. There are also fittings ( LBs boxes etc).
The fittings are sometimes screwed and welded. The weld is to provide a smooth surface so no contanimation can hide. The places I have seen were steamed cleaned often.
Bring plenty of money.
Boiler fronts are not usually a classified area. After all there is a fire not far away.
RE: Stainless Rigid Metal Conduit vs. Stainless Tubing