Cleaning up

 

the bulk of your troubles/expense will be in the connections.

 

I am rethinking just how intrinsically safe an item might be if this is how a new intrinsically safe product starts out.

OP,
You do realize that people with families count on intrinsically safe devices to be safe. They are installed in areas with flammable and/or explosive environments and no amount of training is going to help them if your device fails.

 

Cleaning up, not enough competence in this forum to risk this thread showing up in Google reults

 

[quote="GopherT, post:

 

Just thought of the stored energy of the other device being an unknown. Might see if I can use galvanic isolation instead, will make things easier.

 

I am rethinking just how intrinsically safe an item might be if this is how a new intrinsically safe product starts out.

OP,
You do realize that people with families count on intrinsically safe devices to be safe. They are installed in areas with flammable and/or explosive environments and no amount of training is going to help them if your device fails.

Just saw your unedited reply in my inbox. You really don't have any clue about Intrinsic Safety do you?

It's all very well and good to carry on about the blokes getting home safely, but actually submitting useful help regarding the achievement of that goal appears to be too great a challenge for you.

I have seen a hell of a lot of people receive no guidance at all in this forum because you all think you are better than everyone else. The fact is, you know nothing about other peoples background, nothing about how early on in their research/design they may be and nothing about what they can achieve if they receive a simple answer to a simple question.

There are a hell of a lot of myths regarding Intrinsic Safety (and you probably believe all of them) and I was hoping that there were people in this forum who actually knew something about hazardous area design.

Before certification drawings are certified and accredited by a certified body, a prototype must undergo rigorous assessment to ensure compliance with the standards. Section 7.1 of IEC 60079.11-2011 states the over-ratings at which the components must meet to ensure a safety factor. If a product is too complex to simulate or calculate the stored energy, then it is loaded on a spark test apparatus to determine if it will actually create an ignition.

Now my question was in relation to the inter-connection of Intrinsically Safe devices via RS232 and possibly RS485 and whether limiting their voltages to a lower level would affect the standard. My question was not 'how do I build an intrinsically safe device around an rs232 port'. Further thoughts on this topic lead me to the idea that the manual must specify galvanic isolation for this interface, this leaves the ball in the court of the system designer (rather than myself as the product designer).

Now you know at least a little bit about the certification requirements, perhaps you'll see that AAC has no liability concerns regarding ANY IECEx related product design questions as the product must undergo rigorous certification. As you may have also noticed, the implementation and installation of Ex certified equipment is another ballpark altogether, in which there may be a case of liability concerns.

Some people in this place need a serious attitude re-adjustment.

 

RS232 will more than likely require zener/isolated barriers or repeaters to achieve safety..

 

My intention is to design the device not to fail.

Turning and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;

No such thing. Either you plan for a failure or you've failed to plan.

Hint: "intrinsic safety" embodies this concept.