Remote I/O in a CLI, DV2 location

[dginbuffalo]

Has anyone used remote I/O in a Class I, Div 2 location? The devices I need to interface with are also in a CLI/DV2 area. If my devices are rated as CLI/DV2 am I ok to run directly to remote I/O? Is there anywhere I can find reference material on this subject? Thank you.

 

[cardosocea]

That is equivalent to a Zone 2 in ATEX.

There are a couple of things to be aware of:

- Your cabling must also comply with the rating of the areas it is routed through... if for some reason your cable is routed through a Div 1 area, it must be protected to such a level.

- The communications must also comply in the same way... the manufacturers of the IO will probably have a bus isolator that you can use. It is my understanding that communications are covered under FISCO scheme when using ATEX, not sure about the US equivalent.

- Your IO must be rated for the area it is installed and also for the area that the devices will be installed. This is the less onerous one, so it shouldn't be hard. Bear in mind that if using intrinsically safe circuits (which is likely) you'll need to match your IO, device and cable parameters to ensure you are not exceeding the safe working distance.

ATEX and IECEX is plentiful and most principles will be the same, however it is likely to be subtleties that you should take care of.

 

[damica1]

You may need something like these.
https://www.mtl-inst.com/images/uploads/datasheets/7700/EPS_MTL7700_appn.pdf

 

[dginbuffalo]

You may need something like these.
https://www.mtl-inst.com/images/uploads/datasheets/7700/EPS_MTL7700_appn.pdf

The problem with the Eaton barriers, or most barriers for that matter is that they are shown installed in the "safe zone". The remote I/O would be in the CLI/DV2 zone.

 

[damica1]

You say the devices that you need to interface with is in the c1 div2 zone, but are they rated at c1 div2?

If not, you may need to reevaluate and bring everything up to spec's.

What ever equipment is in the c1 div2 zone must be rated at c1 div2 otherwise you may encounter problems.

 

[cardosocea]

The problem with the Eaton barriers, or most barriers for that matter is that they are shown installed in the "safe zone". The remote I/O would be in the CLI/DV2 zone.

Maybe it's the UL certification, but most barrier systems (and remote IS IO systems for that matter) are usually rated for zone 2 installation, provided that they are installed in an appropriate junction box (usually an Exe style box.

I know Rockwell's Ex IO is like that... and Siemens too. So not sure where you looked.

Are you sure that the sensors are in that same area?

 

[dginbuffalo]

Maybe it's the UL certification, but most barrier systems (and remote IS IO systems for that matter) are usually rated for zone 2 installation, provided that they are installed in an appropriate junction box (usually an Exe style box.

I know Rockwell's Ex IO is like that... and Siemens too. So not sure where you looked.

Are you sure that the sensors are in that same area?

The remote IO rack is rated for CLI/DV2 but you still need to protect in some cases the field devices. They are all installed in the same classification. Zone 2 and Exe requirements are not exactly the same as NEC. I could go with AB Ex IO but it is $$$ and may be overkill for some cases of Division 2.

 

[cardosocea]

Zone 2, Exe and NEC are not related to each other... hence my safeguard on perhaps this being something related to UL certification.

I think perhaps you need to clarify better what it is that you are after.

The Remote IO or barrier will generally have two areas that it is intended for use. One is the physical location of the barrier, the other is where the instruments powered by such barrier go to.

So, a lot of barriers will be rated for ATEX Zone 0, but must either be in a safe area themselves or in a Zone 2.

Under ATEX, if you have more than a single intrinsically safe circuit going into a box, it then must conform to certain specifications. Exe rated type boxes are such a type of box and how most barriers or IO that can be mounted in Zone 2 is.

The field devices themselves may or may not require stringent protections if the protection concept is intrinsically safe... note that I said above more than a single circuit... most instruments will have only one circuit and if intrinsically safe they won't spark. However, most devices will be well protected.

Lastly, you should have some knowledge of the standard before installing these things. It's not that it's incredibly difficult, but there are little things to be aware of.

 

[saultgeorge]

Hi, interesting post. I would certainly thoroughly read article 501 of the NEC. I have done several jobs in classified locations years back, and anything that had to do with the remote racks and other PLC related equipment was located outside the zone. One job was a Class 1 Div 1 Ethanol plant and the other was a Class 2 Div 1 grain elevator. Both jobs had 24VDC and some 120 VAC devices within the zone, but all the wiring and conduit went outside and back to a non-classified location. That could just have been design preferences; (weather and environment concerns, etc), but I would certainly go through that NEC section and it may give you work arounds that are up to code and safe plus saving you some costs. Hope this helped, good luck.

 

[Firejo]

An I/O product can't be rated C1,D2 if it can't be installed while maintaining the rating. If the equipment is rated for C1,D2 then the installation instructions must talk about how to maintain that rating when installed. The wiring must also be rated but it falls under NEC (National Electrical Code) which the I/O equipment's instructions also need to talk about.