Intrinsically Safe Power for HMI

This is downright scary... isn't there any regulation in the US demanding a hazardous area risk assessment that outlines where you have C1D1 or D2 before you install gear in it?

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There are assessments done, in many of these plants they have Assessments and even Area Classification Maps. The point I was trying to make was that in many of the plants I have worked in Class 1 Div 1 is a very small area. Many times Plant Engineers will assume Class 1 Div. 1 just to be safe. When I send them a quote for some equipment and the Div.1 equipment is about double the Div. 2 price they are then forced to go look at the Classification Maps and Assessments to determine if the area is indeed Div.1. Most of the time they find it is not and will then opt for the lower cost item.

So it isn't a "Change the Area Classification to fit the equipment in it" kind of situation. That would be SCARY!! It is more like a "are you sure it is Div 1 area? If not don't pay Div 1 prices" situation.

This is in a nema 1 enclosure which is installed in a safe/unclassified area.

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If it is going to be installed in a non classified area you can use any power supply you want.

So is the solution just to use a Class 1 Div 2 power supply?

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If you have to use a Classified Power Supply then in my opinion Yes that would be the best way to go. Just about every power supply manufacture has Div 2 power supplies. You should have no issues finding one.

James Mcquade said:

once this is figured out, you do the piping, then do the risk assessment, finally get the project stamped by a PE. this is what I had to do at my former worksite that moved north and I was let go.

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You have it upside down or perhaps we are confusing terms. You start with your risk assessment first. You have a process with whatever is flammable and you determine what areas of your process space are classified as C1D1 or D2 or whatever. This will be your hazardous area classification and map.

You then choose the kit that you must put inside those areas. If brand A doesn't make it, you either put a room around it, or install it elsewhere or find someone else that supplies you the kit. You don't start from the client telling you that he wants A or B in said area and then write a risk assessment to suit it.

forqnc said:

Sorry for not including the model HMI, in OP, to avoid confusion.
It's an AB Panelview Plus7 mod. 2711P-T7C21D8S.

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From that number, you can get the ATEX certificate: DEMKO 14 ATEX 1302X

X means that there are conditions of use that must be met... Rockwell is being its usual self and I'm not in the mood to log in, but do check that document for conditions of installation.

Bullzi said:

So it isn't a "Change the Area Classification to fit the equipment in it" kind of situation. That would be SCARY!! It is more like a "are you sure it is Div 1 area? If not don't pay Div 1 prices" situation.

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Or perhaps the better hazardous area protection of them all, don't install anything in them.

cardosocea,

what I meant to say is this is the way I learned it, and I may be wrong in the steps. My boss was the engineering manager and a pe and this is the way he wanted the projects presented and this was the way it was required by the military for that facility.

1. define the area and chemicals in the area.
2. find the suitable hmi display and other materials that meets the requirements for that area.
3. the hmi must be able to be purged / pressurized.
if steps 2 and 3 cannot be met, you find another location for the hmi or something that will work and have the answers. good and bad.
4. do the piping layout on paper with bom based on what you discover.
5. meet with engineering manager, safety, maintenance manager, and maintenance to do the risk assessment on the design presented.

modify plans based on risk assessment and meet again.
6. get the design stamped by an outside PE to avoid conflict of interest if required.

if I have the steps wrong, I apologize.
james

James Mcquade said:

5. meet with engineering manager, safety, maintenance manager, and maintenance to do the risk assessment on the design presented.

modify plans based on risk assessment and meet again.
6. get the design stamped by an outside PE to avoid conflict of interest if required.

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No need to apologize. But if you started from the risk assessment, the review of the design would likely not require any modifications.

As for having to have the capability of pressurising, standards change and it may have been the case that when you had to do this in the military the standard called for it.
Since it was the US military (and I may be wrong in my view of them), chances are that your manager didn't even want to consider different areas and asked for everything to be in Class 1 Div 1, almost like Bullzi mentioned.