Intrinsically Safe HMI for Zone 2, IIA/IIB, T3

I have a customer that is requesting an Intrinsically Safe HMI. I can't say that I've ever heard of an Intrinsically Safe HMI. Anybody here have any experiences with one they like?

in order to make an hmi safe, you must purge / pressurize the enclosure to acceptable levels. all ab terminals that i know of cannot be purged / pressurized because the display will bust under pressure. this goes for all other displays that i am aware of. Maple Systems used to make a computer hmi system that would meet your requirements, but that was years ago for 10-20k depending on your requirements and screen size.
james

Yeah, I typically purge the HMIs I use but this customer is wanting one that has a protection method of Intrinsically Safe. Siemens may have one but making sense of their terrible website is usually more trouble than its worth.

There are manufacturers of different nema rated enclosures, but a terminal by itself would be hard to find.

example of enclosure to put your terminal inside of it.
https://itsenclosures.com/

they offer 4 or 4x with purge systems
https://itsenclosures.com/products/hazardous-area-purge-controls/

I came across the possiblity of Siemens maybe having one as well but like you I cannot stand their web site to look into it much more. Also I am not familiar with non NEC classifications, maybe an IS Tablet would be better suited for the customer?

Siemens makes touchscreen panel PC that are rated for Zone 1 and Zone 2.

I'm now waiting on Siemens to call me back. Their website is just so damn bad.

Snyd1,
2008 version - see NEC 70, section 505
looking at these specs, i doubt the customer will ever get what he wants, too many chemicals, gases.
the companies that i worked for since 2004 has provided me the code books.
james

John Marston said:

Yeah, I typically purge the HMIs I use but this customer is wanting one that has a protection method of Intrinsically Safe. Siemens may have one but making sense of their terrible website is usually more trouble than its worth.

Click to expand...

Try the configurator

https://new.siemens.com/global/en/products/automation/topic-areas/tia/tia-selection-tool.html

Click start tia selection cloud

Select New Device > Industrial PC > Monitor & Thin Client > Pop up click select device series > Simatic HMI Ex tab.....

Then click through each one to see what Ex standards they comply to

James Mcquade said:

Snyd1,
2008 version - see NEC 70, section 505
looking at these specs, i doubt the customer will ever get what he wants, too many chemicals, gases.
the companies that i worked for since 2004 has provided me the code books.
james

Click to expand...

Thanks,

Never had to delv down into the groups before. Glad I do not have to deal with that stuff, not sure I would ever sleep again.

In general, which manufacturers are allowing their HMIs to be purged these days? AB doesn't recommend it, not sure about Siemens.

https://www.controldesign.com/articles/2020/which-hmi-is-best-for-hazardous-areas/

Looks like someone wrote an article on this subject!

Jim3846 said:

https://www.controldesign.com/articles/2020/which-hmi-is-best-for-hazardous-areas/

Looks like someone wrote an article on this subject!

Click to expand...

Awesome, thanks for the link.

Also check out R.Stahl- they specialize in ATEX HMI's

We use their ThinClients- very good.


https://r-stahl.com/en/uk/home/

I'll throw in Bartec and Pepperl-Fuchs for HMI and Thin clients respectively.

When the customer says intrinsically safe, what's his understanding of it? I've seen chemists requesting Exd devices to be made intrinsically safe with a barrier which is absolute nonsense and a likely non-compliance.

I can't remember of one HMI device that is powered by an intrinsically safe circuit as most barriers can't output full amps. Generally the device itself is internally intrinsically safe (the marking features ia, ib or ic within square brackets), but it'll have an additional marking (either d, e or n).

Looking at your requirements though, you can find a bunch of Ex n marked devices that comply with this.

I think the important bit is understanding where this requirement of the intrinsically safe comes from and why as you may well be able to successfully argue that it's either not possible or far more expensive than what they'd be willing to pay.
After all, it's a Zone 2, IIB T3... it's not Zone 1, IIC, T6 so there's plenty of leeway to deliver something fit for purpose without overengineering based on someone's ignorance.