instrument enclosures Class 1 Div I/II

[akebono]

I'm looking for an enclosure manufacturer who can take an existing case and modify it for an instrument that will live in a Class 1 Div I/II environments. There are two issues:

1. the device is 4x6x10"
2. needs an optical fiber connection or low-profile window

Does the forum have any recommendations?

Thanks!
akebono

 

[akebono]

sigh, not so obvious

sigh, not so obvious

Just to clarify,

• the manufacturer should use their enclosures for my instrument (not modify mine, that would be a job for an exproof consulting company.)

 

[weressl]

I'm looking for an enclosure manufacturer who can take an existing case and modify it for an instrument that will live in a Class 1 Div I/II environments. There are two issues:

1. the device is 4x6x10"
2. needs an optical fiber connection or low-profile window

Does the forum have any recommendations?

Thanks!
akebono

Is it your intent to install an instrument otherwise unsuitable for hazardous location in an enclosure that will provide sufficent rating to be installed in CLass I, Division 1 area? Div. 1 suitability automatically makes it suitable for Div. 2.

A purge kit added to a standard NEMA 4/4X enclosure is probably the most universal solution. Pfefferl&Fusch with Hoffman enclosure. Fiber optic connector can be mounted through the wall.

Don't you have any other connections to the instrument, like signal or power or process connection?

How about the generated heat by the instrument?

 

[jlwilk]

Check out R.Stahl. They may be able to offer you some help. They are experts in hazardous location applications.

 

[akebono]

sorry for the delayed reply ...

sorry for the delayed reply ...

Laszlo: Yes, the instrument is, by itself, unsuitable for a hazardous location. It has some unsuitable voltages. Continuous operation in an enclosure doesn't pose heat problems, the instrument is low power (about 10-15W continuous). It will be connected to power and a fiber optic to the process. I would prefer not to use a purged enclosure so that the instrument could (relatively) easily be moved to new locations. Pepperl+Fuchs is probably not an option since they only make purged enclosures.

jlwilk: R. Stahl looks like a possibility.

Any other recommendations?

Thanks!

 

[weressl]

Laszlo: Yes, the instrument is, by itself, unsuitable for a hazardous location. It has some unsuitable voltages. Continuous operation in an enclosure doesn't pose heat problems, the instrument is low power (about 10-15W continuous). It will be connected to power and a fiber optic to the process. I would prefer not to use a purged enclosure so that the instrument could (relatively) easily be moved to new locations. Pepperl+Fuchs is probably not an option since they only make purged enclosures.

jlwilk: R. Stahl looks like a possibility.

Any other recommendations?

Thanks!

Akebono-san,

There are a host of manufacturers who make explosionproof enclosures, such as Crouse-Hinds, Killark, Appleton, etc.

I avoid them like plague. There are 'umptenth millions' of bolts to loosen AND retighten each time when you want to access the device inside. The box's explsionproof intergity relies on ALL bolts being properly tightened, although I believe UL does a test by leaving a random bolt untightened, but not two adjacent ones.(?) There are also host of uncertainities about the number and type approved entries one can have. I am not aware of a fiber optic connector that is approved for an explosionproof entry.

Purging is my recommended way to go. Should you need the enclosure to be movable, you can attach a small compressed air bottle with a pressure regulator which will give months of continuous service before it needs to be replaced.

 

[petersonra]

I'm looking for an enclosure manufacturer who can take an existing case and modify it for an instrument that will live in a Class 1 Div I/II environments. There are two issues:

1. the device is 4x6x10"
2. needs an optical fiber connection or low-profile window

Does the forum have any recommendations?

Thanks!
akebono

I doubt you can modify an existing case and make it suitable for both div1 and div 2. you would likely need a whole new enclosure.

Its entirely possible such an instrument either is or could be made suitable for a div 2 environment w/o modification. Might just require listing.

Div 1 is a much tougher nut to crack. As another poster said, XP enclosures sound like a great answer but they are a real pain in the you-know-what above the very small sizes with the screw on covers.

I am not sure why so many people refuse to consider pressurization as a protection option. It is often the most flexible, simplest, and least expensive option, and most times requires no modifications of existing stuff beyond addition of the pressurization/purging equipment. And these days you can buy that as kits.

 

[rbalex]

Mobility has somewhat painted you into a corner. Any suitable R. Stahl enclosure for Division 1 will still be explosionproof or require auxiliary protection techniques. This goes for any manufacturer.

So, I tend to agree with Laszlo with a few potential caveats.

?Purged and Pressurized? is definitely a recognized protection technique in the NEC ??for equipment in any hazardous (classified) location for which it is identified.? The FPN in the definition in Section 500.2 suggests that NFPA 496 is the best way to determine that the technique will be ?identified.? You might also want to review Section 500.8 (A) carefully.

I see no general problem with using a bottle of non-flammable gas to pressurize the enclosure. The issues will potentially arise from NFPA 496, Chapters 4 and 5, especially in Division 1. You will need to adopt several specific operating procedures and deal with various alarm and shutdown issues for unattended operations.

 

[weressl]

Mobility has somewhat painted you into a corner. Any suitable R. Stahl enclosure for Division 1 will still be explosionproof or require auxiliary protection techniques. This goes for any manufacturer.

So, I tend to agree with Laszlo with a few potential caveats.

?Purged and Pressurized? is definitely a recognized protection technique in the NEC ??for equipment in any hazardous (classified) location for which it is identified.? The FPN in the definition in Section 500.2 suggests that NFPA 496 is the best way to determine that the technique will be ?identified.? You might also want to review Section 500.8 (A) carefully.

I see no general problem with using a bottle of non-flammable gas to pressurize the enclosure. The issues will potentially arise from NFPA 496, Chapters 4 and 5, especially in Division 1. You will need to adopt several specific operating procedures and deal with various alarm and shutdown issues for unattended operations.

Yes, yes, it will not be something that you install-and-forget.

Unless you go with the XP enclosure, but as I said I am not aware of any connectors that would facilitate the disconnectability of the fiber. You may consdier installing an XP seal atatched to the XP box then have the fiber connector in an ordinary box attached to the opposite side of the seal. Other connections will also need to have an XP seal with a union that you can break and when you remove the XP instrument box install an XP box on each to coil up the wires that were connecting to your instrument. This is if you intend to reuse the locations to connect the XP instrument. Wireless could work for the signals but not having Mr. Tesla around leaves your power connection hardwired.

 

[petersonra]

somehow I have a vision of someone coming up with a requirement and not realizing the impact of what they are asking for.

 

[akebono]

impact of requirements

impact of requirements

somehow I have a vision of someone coming up with a requirement and not realizing the impact of what they are asking for.

Well, that is one of the functions of marketing isn't it? They take unfiltered comments from potential customers and write it into a specification.

Thanks to all for the discussion, I needed to hear the problems with the requirements. The problems dictate feasibility and time-lines. It looks like a long road. I'll need to read through the posts a few times before I post additional questions.

Thanks everyone!