Explosion Proof Enclosures

[blemmon]

We want to make several of our products meet explosion proof standards. The application is for sensors w/ low voltage signal connections in an explosive environment.

Can anyone direct me to a starting point?

For example:
1) What is the best Standards Agency to use to have a product recognized as explosion proof? UL?, NFPA?, NEC?, etc.

2) Who is the best agency to obtain standards for explosion proof enclosures, connections etc. in order to meet codes in my product design?

Thanks in advance for any help.

-Bob Lemmon
Myers Vacuum Co.
Kittanning Pa

 

[blemmon]

btw- I should mention that I have researched this some and my confusion is in the various standards such as NFPA70, UL698, NEMA250, etc.

If anyone is experienced with getting explosion proof fittings, etc certified, I would appreciate your input.
Thanks,

 

[petersonra]

My mom is from Kittanning, Pa.

FM, CSA, and UL all deal with determining the suitability of equipment for use in hazardous environments.

I don't know what kind of device you have in mind to get evaluated, but there are a lot of evil things that can trip you up.

It is often far more cost effective to arrange for whatever you are making to be installed on an IS circuit.

It is not a whole lot more expensive to get UL to list a device as suitable for use in a division 2 area, than what it costs just to get a listing in the first place.

But getting an explosion proof listing is a different story unless you use components they have already accepted.

BTW, I was told by someone who went to get a UL listing on a relatively simple device that they estimated it would cost $20,000 to get it tested and listed.

 

[blemmon]

My mom is from Kittanning, Pa.

FM, CSA, and UL all deal with determining the suitability of equipment for use in hazardous environments.

I don't know what kind of device you have in mind to get evaluated, but there are a lot of evil things that can trip you up.

It is often far more cost effective to arrange for whatever you are making to be installed on an IS circuit.

It is not a whole lot more expensive to get UL to list a device as suitable for use in a division 2 area, than what it costs just to get a listing in the first place.

But getting an explosion proof listing is a different story unless you use components they have already accepted.

BTW, I was told by someone who went to get a UL listing on a relatively simple device that they estimated it would cost $20,000 to get it tested and listed.

Thanks for your input Bob.
As I continue my research it is obvious it will be expensive, and timely, to get this product certified. I am thinking my best route may be to find some way to house this in some fittings already listed as explosion proof.

btw- Are you any relationship to Dwight Peterson. He was an IE whom I worked with for years at PPG Industries? He was either from Ford City or Kittanning.

 

[petersonra]

no relation.

UL has a program for control panel manufacturers making panels listed for use in hazardous areas. If you can create whatever you want to sell out of parts that are already listed, you might qualify under that program.

UL's definition of a control panel seems to be any assembly that has wires, so you may be able to get by under that listing.

 

[renosteinke]

explosion proof enclosures

explosion proof enclosures

First of all, there are a number of ways to make something suitable for use in a classified location. The "real experts" on the subject are the "instrumentation" folks. Their stuff is available through them www.isa.org . They are the folks who keep oil refineries up and running.

Once you have decided how to address the issues in your product, then I suggest you look at the appropriate UL standard, and see if it looks like your design will work. If so, then find someone to test your product.

The various tests generally assume that a dangerous situation will occur within the product.... so the product is filled with this mixture, set in a chamber also filled 'to go boom'.... then an explosion is made to happen within the product. The idea is that if the room also goes 'boom,' you fail. I think you can see why it is worthwhile to have someone else vouch for your product.

Apart from the "boom" test, the standards typically also require the product to pass other tests... tests like temperature measurements, corrosion resistance, vibration, ageing, etc.

Now, it is no surprise you are bewildered by the various standards. In many cases, the same code will appear from one group to the next- the only difference being the name. This is because there most certainly is a deliberate effort by all concerned to work together. Let me over-simplify things a bit.
CODES are laws we must comply with. For matters electrical, the NEC is the most common place to start. It tells you whay must be accomplished by an installation.
Installations are made of parts. NEMA standards help define those parts. However, complying with NEMA standards is both voluntary, and based upon the word of the manufacturer. UL, and other testing agencies, attempt to police this with their testing and inspection programs. Now, nobody wants to be a rouge... so UL, and others, attempt to have their standards (the testing methods) enshrined as "national" standards by some semi-governmental body (NIST, ASTM, etc).

The idea is that not only will a product work as advertised, but that it will perform under real conditions. It simply wouldn't do for, say, an outdoor device to only work on sunny days!