Zone 2 - I.S Barrier

Hi.
I have a Rosemount 2700 Micromotion flowmeter (Non-I.S model) which is in Zone 2 hazardous area connected directly to a non I.S Siemens analogue input card.
The transmitter has a separate 24vdc power along with an 'Active' 4-20mA output
Questions -
1. Do I need a barrier as its in Zone 2 ?
2. If so, what barrier would be on an 'Active' 4-20mA signal (not loop powered from PLC)
 
Yes you do need some form of protection, and an IS barrier is the easist retro-fit.
I would also find out why a barrier isn't already there - maybe 'Zoning' is recent and flowmeter existing.

There are a few major makes of barrier -
Pepperl+Fuchs'
Phoenix
MTL

If this is an existing site then I would use the make they are already using - in fact they should really have a spare for you to use !
Assuming this barrier is to be fitted / wired in the control panel and there is a 24vDC supply to power it.
Wiring between barrier and transmitter should be blue sheathed and preferably segregated from other cabling -
only once could I not do that so wrapped blue PVC tape round the cable at both ends.
 
Yes you do need some form of protection, and an IS barrier is the easist retro-fit.
I would also find out why a barrier isn't already there - maybe 'Zoning' is recent and flowmeter existing.

There are a few major makes of barrier -
Pepperl+Fuchs'
Phoenix
MTL

If this is an existing site then I would use the make they are already using - in fact they should really have a spare for you to use !
Assuming this barrier is to be fitted / wired in the control panel and there is a 24vDC supply to power it.
Wiring between barrier and transmitter should be blue sheathed and preferably segregated from other cabling -
only once could I not do that so wrapped blue PVC tape round the cable at both ends.

Hi
Thanks for the reply.
I also had a reply from Emerson themselves !! ..........
**************
Hi Stuart,
Intrinsic Safety is not required in a Zone 2 area. Based on the information below, the 2700 is installed in a Zone 2 area, and connected to a Siemens Analog input card. As long as the Siemens device is also in a Zone 2 (or Safe) area, no barrier would be required. The only condition where a barrier may be required would be if the analog output wiring extended from a Zone 2 area into a Zone 1 area.
*************



Regards,
 
Doubled checked the facts...
Zone 1:
An area in which an explosive gas atmosphere is likely to occur in normal operation;
Zone 2:
An area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it occurs, will only exist for a short time.


In my opinion very bad advice from Emerson - I assumed the PLC is in a safe area.
It would not be the first time Zone 1 and 2 have been mixed up ....
 
Doubled checked the facts...
Zone 1:
An area in which an explosive gas atmosphere is likely to occur in normal operation;
Zone 2:
An area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it occurs, will only exist for a short time.


In my opinion very bad advice from Emerson - I assumed the PLC is in a safe area.
It would not be the first time Zone 1 and 2 have been mixed up ....
Hi
Yes I thought that also!!
I have replied to that answer from them to clarify.
Thanks for your help
 
stug,
it's forbidden to use flowmeter or transmitter without Ex certificate in hazardous zone. No matter if you use IS barrier or not. You have to change your flowmeter on Ex proof and relocate your analog device into safe place.
Moreover, if flowmeter doesn't have EX IS certificate, than most likely it will not work with IS barrier.
 
MaratAfl is spot on. Yes, one solution if possible is to move it in a safe area if it hasn't got protection.
Check the transmitter label. It will state the method of Hazardous area protection. Zone 2 still needs protection. If it has none, then device is non compliant and must be removed /replaced.
If it hasn't got a IS label /certificate then it cant be used in an IS circuit. Unless its a simple device, which its not.
Emerson are wrong on two counts; 1. of course "IS" can be still be used in a zone 2.
It's perhaps a bit of an overkill, but certainly, you can still legally use it.
Used in an IS circuit, the transmitter and the entire IS loop, with all its components, have to be certified Ex "ia" . Further more, all the said components, including transmitter, blue cables/barrier have to undergo an Entity calculation. Intrinsic loops ,JB's and cables are usually segregated from other types of hazardous area circuits.
2. No! Emerson! it cant simply be wired up to an input card, as the transmitter still needs a label/certificate No. showing its method of hazardous area protection, even for Zone2.
The input card if its not in a safe area, then it too needs rated enclosure protection.
 
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