Is Across International equipment really explosion proof?

Our reactors are rated C1D2, but I found that meeting the requirements for C1D1 to be too difficult and costly. To my surprise AI started selling reactors a while back rated as C1D1. I noticed some issues in their pictures, but figured that PSI knows more than I do so just considered the picture to be incorrect or old or something. So I reached out to PSI to ask a couple of questions

  1. How do they have a C1D1 rating but use liquid tight conduit? (Liquid tight conduit per code can only be used in C1D2 applications. C1D1 requires a hard conduit, or at least a flexible UL C1D1 rated conduit like here)
  2. Are all the components they are using UL and C1D1 rated? Some look like they are, other do not.

PSI responded
“We have only approved the designs of the Across International glass reactors R10, R20, R50, and R100 and stainless reactors SR100, SR200, & SR300. Neither of which had a control panel as shown in the photograph”
Maybe they started the process with a different design or something but it seems they used that initial certification to apply to explosion proof reactors with different model numbers or features which should have triggered another certification. For example the PSI link lists only the non-explosion proof models, but there should be a different link and certification for the C1D1 reactors that states its model numbers R10ex, R20ex, etc.


Probably website guy issue? (I want this to be the issue)

One would think Explosion proof motors would be linked.

Maybe the entire thing as a whole gets a UL listing?

Definitely curious how they’ve navigated this as well.

Or you’re expanding that they’re expanding their approval for products not reviewed?

Yeah not sure, there’s probably a simple explanation but so far this seems odd. I sent the picture of the explosion proof reactor and the head of engineering at PSI said he never saw that control panel. You would have to submit that control panel as part of the C1D1 model design. That control panel would have to be wired by a UL 698A certified shop in order to be stamped with any kind of NRTL for hazardous use. All components in the enclosure and all electronics in the entire system have to be UL or NRTL certified and only then should PSI certify it. I honestly don’t know how they could achieve this with a C1D1 enclosure which by itself costs thousands of dollars.

China Chinas

In the end… C1D1 compliance will always depend on the particular setup of the equipment within a regulated environment.

You can get a “C1D1 compliant” piece of equipment and have it installed in a manner that in non-compliant.

What I’m saying is take all of that shit with a grain of salt. What you need is an engineer that will go to bat for your final install with a seal and a signature that gives that weight.


I have one and can take a look. What should I look for?

we changed the motor on the r50 to a pneumatic drive one so it could be in the booth

Please don’t throw PSI under the bus here. They are reviewing equipment using standards that are very much open to interpretation in many cases. Plus, I know for a fact the system approvals page hasn’t been updated in quite some time (because they haven’t updated with new listings for us and some of our competitors for at least a year and a half).

I’m leaning more toward an inaccuracy on the website, as opposed to any kind of selective application of the codes.

Then again, because of the nature of the codes being open to interpretation, sometimes it leaves an opening to intelligently argue the acceptance of something that traditionally wasn’t allowed. I know this because I had to argue that our control method did not need UL508 because it did not fit UL’s definition of a “control panel”. 2 affidavits and a detailed email from a senior application engineer later, we had our approval.

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If it’s an explosion proof reactor check to see if it has liquid tight conduit. Is the control panel and enclosure certified?

Actually PSI has been open and honest but they also don’t really want to open this can of worms so it’s hard to get info from them.
It seems most likely a clerical error or website discrepancy but I can’t say for sure.
I don’t want to throw any shade on anyone but I just don’t know how they got that C1D1 certification so I’m hoping to learn something new here. Please someone prove me wrong.


From a 5 minute check of AIs website, it looks like their perr reviewed model uses a pneumatic stirrer instead of an electric one. Thus no conduit to cause problems.

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This is the model I am talking about. Not the stainless steel ones. Obviously an air motor wouldn’t apply here. I’m only talking about the electronics.
It says explosion proof motor and controller in the listing title. They are advertised as C1D1 and PSI reviewed to be used in a C1D1 environment

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Sounds like more of you telling us than asking.

Don’t get me wrong it’s a very valid point.

The resolution of the pics on the AI site is not great but to me this looks more like MC-HL and not standard liquid tight (LFMC or LFNC) the red on the fittings gives it away but the code states the fittings have to be listed (by a NRTL) for the special occupancy and this can be easily faked.

Given the environment of the use of this equipment if it were field assembled and all the components were Listed I think there would be no issue satisfying the requirements of NFPA 70 501.10 (A) (1) (3). But, being sold as an assembly most AHJs will require a Listing or engineer for the entire assembly. You may be able to get there by working with a UL Industrial Control Panel shop with a hazardous location endorsement.

You’ve identified an obvious discrepancy between what PSI has reviewed as C1D1 and what AI is claiming on their site and that should be addressed. This isn’t too different from what I’ve seen other venders on this site have clamed on their equipment to be PSI stamped and have the electrical totally wrong, I’m starting to wonder if the electrical portion is outside of their scope.


Thank you I appreciate the info. The difference between component level and system level certification has been somewhat misunderstood by most users or customers. Honestly the fire inspectors don’t really seem to care that it’s not field labeled, but we’ll see if that changes in the future.
Having the complete assembly certified is ideal, but as long as the component/design level certification is solid then it should be fairly safe and acceptable to use. If the design or build doesn’t follow code, or non-NRTL rated components are used then it is unsafe and a liability issue.


I disagree. Refer to my comment regarding how codes are often very open to interpretation.

This is the bigger issue many businesses are worried about. :man_shrugging:

Yes it is