Instrinsically safe control system

I've been asked to advise on a propane filling system that customer wants to use scales, PLC, HMI, all located in the Quonset hut where filling takes place.

Assuming I can find a reasonably priced IS HMI, and enclose the PLC in NEMA 5 box and provide IS barriers for signals, etc., how would one go about connecting to the PLC / HMI for program updates, etc., without disturbing the explosion proof requirements?

danatomega,

I don't know your background, so I am going to point some things out.

unless you are a registered engineer and willing to place your stamp on the drawings and assume liability, you really can't advise someone on the installation.

this will be a gas hazard area, class 1 environment, you will be dealing with nec 70 articles 500-5??.

they do not make nema 5 enclosures.
you must meet the enclosure requirements, purging / pressurizing requirements of nfpa 496 may apply.

rigid conduit, sealoffs, barriers and other things need to be considered.

your costs sky rocket.
regards,
james

danatomega,
From my interpretation of your question, I agree with James. Purged panels, seal-offs, threaded pipe, etc., etc. Price tripled in just a few words.

I work in class 1 Div. 1 very often. I don't know of anyone that makes an explosion proof HMI, or Laptop. You can use Ethernet and xp pipe it out of the classified area or just add a wireless router if you area is small enough.

Thanks for the replies.
Probably should just pass this one by ...

The last time I attempted this I ended up just putting explosion proof buttons and no touch-screen interface. I put a regular big screen monitor outside the environment where they can see through a window. Now I think about it, maybe there are such thing as intrinsically safe keyboard/mouse since there are IS radios.

hey, found some:

http://www.stealth.com/peripherals_intrinsicallysafe.htm
http://www.d3inc.net/product-keyboards-6900.html

danatomega said:

Thanks for the replies.
Probably should just pass this one by ...

Click to expand...

Smart move!!
And... that 3X price estimate is way too low!!