Hazardous Area Rating of Security surveillance cameras 1

[AnarV]

As per existing design, lighting & small power and telecom installation along perimeter fence of our facility are non-EX-certified. Perimeter cameras need to be on all the time and no isolation of power supplies to the cameras would be acceptable by plant PSD system upon gas detection from security point of view. All of the cameras are located in non-hazardous area as per existing Hazardous Area Drawings. However, some of them are located closer than others to boundary of some Zone 2 Areas.
What is the best way forward? Is there a consistent approach in the industry? Shall we only EX rate those downwind of potential leak sources? Or only those located close to Zone 2 boundary? Also, what does "close" mean in this case?

 

[AnarV]

I have tried to search other Q&A Forums for answer but the uniqueness of this issue is that we cannot shut down this cameras in case of shutdown caused by gas leak being detected by plant Fire & gas equipment. All of them are outside hazardous area, some are more close than others, som eare down-, some are upwind as I said. So I really do need the experience of this community.

 

[Compositepro]

Equipment has to be rated for area it is in. You say the cameras are outside the hazardous areas. So what is the problem? The rules for establishing the boundaries of hazardous areas takes into account the possibility of leaks.

 

[IRstuff]

Even if your camera is one angstrom outside of the hazardous area, it's outside, and should not subject to the requirements inside. If you think there's a risk of explosion from the camera, then your boundaries are incorrectly drawn.

TTFN

FAQ731-376

 

[DRWeig]

If you're in the US, there is an ANSI/ISA recommended practice for classifying hazardous locations. I think it's RP12.06.

If the boundaries are drawn according to the standard (with the interpretation of a licensed engineer who is experienced with classifying areas), IRStuff's answer applies. Inside the zone, make it suitable for the zone. Outside the zone, it's not a problem.

Don't get concerned with what's downwind or upwind. The wind doesn't always blow the same way!

Good on ya,

Goober Dave

 

[AnarV]

Thanks for your views gentlemen, I am just trying to be as conservative as possible because if you stick to API RP 505 stipulations the rule says that you don't need to do it as it is purely outside any Zone.

However once you start doing actual consequence modelling of gas release from a sample of sources close to surveillance cameras the result shows that gas at LEL can reach the camera. So the standard itself is very generically optimistic I must admit.

I am looking for the "golden balance" here between API and actual consequences. Depending on what the views are here, we might end up doing consequence modelling for each camera (or for each downdind camera)...


About wind: well, we do base some of our stuff on predominant wind direction (which is 70% from NE at our facility) and rather than making all of the cameras EX (worst case this migh end up with) we can just make those which are downwind because it is veyr unlikely that a gas release occurs with simultaneous "bad" wind direction. So far gas releases at our facility have been very rare events.

 

[IRstuff]

Again, if you're getting into trouble with the cameras, then your boundaries were either incorrectly calculated, or something in the process has changed to nullify the analysis. If this is the case, then your safety boundaries should be re-calculated, otherwise, you might be OK for your cameras, but someone else might introduce something outside of the boundary and wind up causing an incident or damage because the boundaries are not actually correct.

TTFN

FAQ731-376

 

[AnarV]

We did re-check the boundaries against the standard and they do comply. As I said, the standard is very optimistic. Actual consequence modelling does prove that the gas can get to the camera locations.

 

[MikeHalloran]

So now you've gone to sea with two clocks, and they don't agree, so you don't know what time it is, so you don't know where you are. ...So to speak.

Why did you, er, go to sea, in the first place?



Mike Halloran
Pembroke Pines, FL, USA

 

[IRstuff]

If you believe your modelling, then the boundaries need to be reset. Futzing with the camera requirements obscures the real reason for doing so, which is that the boundaries need to be extended outward.

Once that's done, you have a clear case for requiring modifications to the cameras that are now inside of the safety boundaries.

TTFN

FAQ731-376

 

[Bilegan]

If plotted on your demarcated hazardous plans and elevation drawings that your perimeter camera is located or falls within the electrically classified area, i.e. Class 1 location (gases or vapors), then you will provide and install an explosionproof camera suitable for Class, Division/Zone, and Gas group on the propose location of installation.

However, if you plotted on your demarcated hazardous plans and elevation drawings that your perimeter camera is located outside or falls within the unclassified area, then provide and install a camera with weatherproof enclosure suitable for your specific outdoor environment.

The perimeter camera which are propose to be installed near the Zone 2 areas and those within downwind of potential leak sources are not required to be provided with explosionproof enclosure as it is not mandated in the industry codes and standards, i.e. NEC, API-RP, NFPA 497.

Regards,
Bilegan

Murphy's Law - If anything can go wrong..it will.