RFID for Class 1 Div 2 Hazardous Location

Hello everyone,
I was curious if anyone has heard or used any RFID equipment in a Class 1 Division 2 hazardous location. Methane gas is the hazard and will definitely be encountered in the location. I am using AB control logix PLC's in several locations (all hazardous) and was hoping to implement a RFID system for personnel tracking with a serial or ethernet interface to my CPU's. I would like to be able to see when different people (roughyl 25-30) are in the hazardous enviroment and was hoping to use a tag that can be worn on clothing. I have found several systems that meet the application requirements but am having trouble finding a system that meets the Class 1 Division 2 certification (CSA, UL, FM etc.) Has anyone seen or used a similar system? Any advise or input would be much appreciated.

Thanks.

Maverick,

The No. 1 rule for electrical equipment in hazardous areas (especially Class 1, Division 1) is:

Move every sparking and arcing device outside the hazardous area, or at least move it into a lower-class hazardous area.

I would locate my RFID at the doorway or entrance into the Class 2 area, then use non-rated equipment for "normal" areas. It usually saves enough money to more than offset any additional cable and mounting hardware.

Any equipment with low-power, "intrinsically safe" (1.2 volts, 0.1 amps, 25 milliwatts) is generally considered safe for a Division 2 area, according to US National Electrical Code Article 504.

25 to 30 people in the area? Wow, I bet the Life Safety Code will require that you ventilate the area to remove any harmful vapors. If you have ventilation, then suddenly the area gets reduced from a Divison 2 to a non-hazardous area! I would think you would want some mechanical ventilation anyway, just out of consideration for those 25 to 30 people who have to go in there.

Rethinking the problem, it may be that the area has already been reduced from a Division 1 by the use of positive ventialtion. In which case, go back to Rule No 1!

Yes we have lots of mechanical ventalation. That is the only thing that keeps us from being a Class 1 Div 1 environnment. Since we have the ventalation we are Class 1 Div 2... I also try to keep as much out of the hazardous location as possible. However, this is not really feasable most of the time since all of the CPU's and equipment is within the hazardous location and is quite large. I must have some of the reading equipment inside the hazardous location to determine direction of travel and approximate location. The other thing that would be inside the hazardous location is the tags that the personnel are wearing... any ideas?

I will look up the older information I had but I have run accross an Irish company in the past that got its start from making tags and reader system for whiskey barreling operations.

I'll post back in a while.

Darren

Sorry, but I have been unsucessful in locating the information. If I eventually run accross it I'll post the info here.

Darren

Why do you say it is not feasible to locate stuff outside the hazardous area? Every gas station in the country has to locate the disconnect switch to the gas pumps outside the hazardous area of the pumps! (Yet I still see idiots smoking a cig while filling up their tank!) Non-rated equipment inside an honest-to-God hazardous area is a self-correcting error: Things go BOOM! in a very short time.

This shows that you do not REALLY believe that the area is hazardous, or you would not even CONSIDER putting any arcing, sparking devices in there! If your area has been incorrectly classified, that is a whole different can of worms.

If you have figured out a way to legally locate "all of the CPU's and equipment" inside a hazardous area, then a reader or scanner should be easy. You could put it inside a positive-pressure-outside-air ventilated cabinet, with a lift-up or spring-closing sliding interlocked door, and then use regular old equipment from any vendor.

A positively pressurized cabinet (inside a Division 2 area) creates a small non-hazardous area, as long as interlocks are added to prevent opening the cabinet if the pressure is not positive.

The tags should be "intrinsically safe" because they are not capable of producing more than 25 miliwatts of power.

Lancie1 said:

The tags should be "intrinsically safe" because they are not capable of producing more than 25 miliwatts of power.

Click to expand...

I would think the larger issue (which was my problem automating some whiskey tracking) is the antenna.

Darren

Thanks for the responses. Let me clarify a little bit about the location that I work in... this is a tunnel project and we use explosion proof boxes to house all "hazardous" equipment. We also use intrisically safe equipment and devices that are appropriately classified. This is the reason that we cannot locate the hazardous equipment outside the area... the area is increasing everyday and will eventually be miles long, so I think you can see the problem...
Undergroud we worry about methane. We don't always have it but it can change from nothing to dangerous levels extremely quickly. So yes, this really is a hazardous.
I want to be able to track people entering and leaving this envrionment. This means that I can put the scanner just outside the area but also need one inside the area to tell direction of travel. I was hoping that people could just wear the devices and not have to worry about them. Otherwise they get lost or people forget about them...

The RFID tags are actually powered by the RF from the reader. IOW they have no internal power source & are hermetically sealed. Shouldnt be a problem with the tags.

So what you do is get a duel reader controller with an anti-passback feature. Mount the two readers outside the hazardous area in an entry & exit breezeway. The readers we use are powered by 5vdc @ 100mw and are also hermetically sealed with a pigtail cable. The wiegand signal from the reader tells the controller exactly what reader went which way and at what time, day etc.. Tracks 10s of thousands of events. Up to 65000 tags. You use a PC to track who has what tag & the permissions & events etc..The PC can be connected to the controller RS-232, RS485, wireless or Enet.

What you should also really do is have the reader release a turnstile to assure nobody passes thorugh (either way) without the tag actually being detected.

Opinion: In the event of a disaster you absolutely need a fur-sure fire way of knowing who's in and who's out. If you do this electronicly, and the catostrophic event takes out your power or RFID system, then your S.O.L. and left guessing. Stick with the good old & time proven brass tag system.

Hi Mike,

Thanks for your suggestions and comments. We do have and use the brass tag system currently. However, there is talk of new laws requiring electronic identification systems and I was asked to look into feasability and possibly implement a small system as a sort of trial run. Also, if the tags are tracked as people enter and exit then in case of catastrophy there should already be a record of who went in and out prior to the event... unless I am missing something about how the reader stores/transmits the tag data.

No your not missing something. It's just my thoughts on possable loss of power or something that would prevent the use of the PC.

Anyway what you could do is have the computer print a report on each exit/entry event or use a UPS to back up the RFID system.

As I understand it some new mine code proposals are being floated to track the actual position of each individual in the tunnels. That's entirely different from an IN / OUT system & would require an array of readers throughout the entire underground area. The idea is to be able to readly locate each individual. The issue is that type of system is still under development. There's no proven system on the market yet.

Maverick, check this out:

http://www.idesco.fi/products/pdf/exreaders.pdf

Yes, you are correct about the new/potential mine codes regarding tracking of personnel. We were looking at this as a crawl, walk, run project. Also, it is a little different in a tunnel... there is only one way in and one way out. There are systems available overseas that I have seen in use but they primarily use "leaky feeders". I have also seen systems that use active tags with a battery supply. Tracking the position is a little different with these active tags as far as I can tell though, the tags report a signal strength based on the distance to the reader which can vary depending on how the system is set up. The other problem is that the systems I have seen are not approved by US standards and ATEX is not acceptable for my application. I understand your comments about power loss. If we had to use PC then it would be located on the surface which has a totally seperate power feed from anything underground. We have seperate high voltage drops power supply drops for our equipment underground so they are independant of surface supply power. If we have problems with both at the same time then there is likely city wide problems. Regardless, we make use of UPS systems for data acquisition and would do the same if we implemented a RFID system with a PC.

Thanks for your comments.

Just saw your post about the IDESCO after I made my last post. It has caused me a lot of headaches with the ATEX versus US approvals. I wish there was a universal cross-over index that would get passed some of this. I have some major equipment from overseas that was a major pain to go through and have checked for compliance to US standards...

I cant seem to find any info on crossing ATEX to ASME/NEC Class-Division etc.. at the moment. But my bet is there's someting compatable.

If this is just a test of sorts, place an open-air enclosure just outside the tunnel entrance and place your readers there.

Two outside type readers & the controller would cost about $1,200.00. Tags can range from $6-$10.00 each. Software and comm equipment maybe another $1,000.00. Not really that expensive, considering.