Intrinsic Barriers & non-incendive instruments

Do I need to put intrinsic barriers on instruments that are rated Class Div 2 and non-incendive?

The mass flow controller tech support person says intrinsic barriers are not required because it is a non-sparking device. The MFC requires 24vdc to power it and pulls 1/2 amp.

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My project will have some pressure transmitters and mass flow controllers installed in a Class 1 Div 2 area (don't know group yet, customer to tell me). All are rated Class 1 Div 2 and are non-incendive.

Any thoughts?

I would think so because a barrier will limit the current available going out to the device so that if a wire gets cut or broken there is no possibility of an arc.

dogleg43,

before i can answer, several questions for you.

#1 what is the classification of the area you are puting the sensor in? Class 1,2 div 1,2 group?

#2 what is the chemicals you are working with?

#3 what is the classification of the instrument? you state div 2, but what class?

#4 what is the instrumentation requirements of the equipment you are connecting to?

please look at nfpa70, electrical code book, section 500-520?
for installation requirements.

you need to know all of the above before continuing.

your question is very general and i cannot answer without more details.

regards,
james

James Mcquade said:

dogleg43,

before i can answer, several questions for you.

#1 what is the classification of the area you are puting the sensor in? Class 1,2 div 1,2 group?

#2 what is the chemicals you are working with?

#3 what is the classification of the instrument? you state div 2, but what class?

#4 what is the instrumentation requirements of the equipment you are connecting to?

please look at nfpa70, electrical code book, section 500-520?
for installation requirements.

you need to know all of the above before continuing.

your question is very general and i cannot answer without more details.

regards,
james

Click to expand...

James,
Working on it and will post what I find out later. Thanks for the info so far.

James Mcquade said:

dogleg43,

before i can answer, several questions for you.

#1 what is the classification of the area you are puting the sensor in? Class 1,2 div 1,2 group?

#2 what is the chemicals you are working with?

#3 what is the classification of the instrument? you state div 2, but what class?

#4 what is the instrumentation requirements of the equipment you are connecting to?

please look at nfpa70, electrical code book, section 500-520?
for installation requirements.

you need to know all of the above before continuing.

your question is very general and i cannot answer without more details.

regards,
james

Click to expand...

[FONT=&quot]James,[/FONT]
[FONT=&quot]Thanks for helping me with this problem. [/FONT][FONT=&quot]I’ve been boning up on the NEC sections you recommended.
Below is all of the information I believe you requested:[/FONT]
[FONT=&quot]
All of the instruments are located in a Class 1 Div-2 Groups C & D rated area[/FONT]
[FONT=&quot]
Chemicals present: Acetone, Methyl acetate, Methyl ethyl ketone (MEK), Tetrahydrofuran (THF), Methanol, 2-Methyl-THF, Isopropyl acetate, Methyl cyclohexane, Ethyl acetate, Ethanol, Heptane, 2-Butanol, Isopropanol, n-Propanol, Cyclopentyl methyl ether[/FONT]
[FONT=&quot]
The instruments are several pressure transmitters and mass flow controllers. All of them are rated “Non-incendive for Class I, Division 2, Groups A, B, C, and D”.[/FONT]
[FONT=&quot]
The pressure transmitters are loop powered 2-wire devices that have 4-20mA w/Hart.[/FONT]
[FONT=&quot]
The mass flow controllers have 4-20mA inputs and outputs. They also require 24VDC to power them. Per the manufacturer the max power rating is 4 watts @ 24VDC.[/FONT]
[FONT=&quot]
The MFC’s tech support guy checked with another person and both said "there is no need for an intrinsic barrier for anything on their controller."[/FONT]
[FONT=&quot]
From what I've read in some literature about intrinsic barriers they may not be needed because everything is rated for the application and are non-incendive. [/FONT]
[FONT=&quot]
Your comments would be appreciated.

Thanks
[/FONT]

Dogleg,
If the equipment is rated for the classified area and the manufacture does not recommend or require a I.S. barrier to be installed with their equipment, then the equipment can be used in the classified area without a I.S. barrier.

Make sure that you properly conduit all the equipment for the area classification. Seal offs and proper conduit fittings will be required.

What brand of Coriolis meter are you installing? All the meters I have used are rated Class 1 Div. 1 or Div.2.

Good luck

Bullzi said:

Dogleg,
If the equipment is rated for the classified area and the manufacture does not recommend or require a I.S. barrier to be installed with their equipment, then the equipment can be used in the classified area without a I.S. barrier.

Make sure that you properly conduit all the equipment for the area classification. Seal offs and proper conduit fittings will be required.

What brand of Coriolis meter are you installing? All the meters I have used are rated Class 1 Div. 1 or Div.2.

Good luck

Click to expand...

Bullzi,
The mass flow controllers are Brooks SLAMfxx models and are not rated for Class 1 Div 1, only Class 1 Div 2, and Class 1 Zone 2.

This is an existing process and none of the other wiring in that area have sealoffs, just open tray cable.

That being the case, I would be VERY Careful about the installation. Look at the installation manual for the device(s) and make sure that seal offs are not required.

In most Class 1 Div 1 areas (which is what I am most familiar with) conduit must be sealed with in 18" from the device and also when you leave a classified area. This is to prevent vapors from entering a area that my cause an explosion. With Div 2 areas and tray rated cable there may be a different sealing fitting that you can use but some kind of seal is normally required.

I did a little more checking.

If the device is Class 1 Div 1 rated then it will need a seal off. If the device is Div 2 rated you do not need seal offs.

With tray cable you don't need sealing as long as you don't run into a building or confined space that borders the Classified area. In other words if you have a wall that boarders the Div 2 area and you penetrate that wall.

So if you run out of the Div 2 area into a unclassified area and then run into a building you are good.

The devil is in the details. Where does the classified area end and the unclassified area begin?

It's a small process system with everything in the same room. The panel is a ways away from the process system. Evidently the panel considered to be a safe distance away from the Class 1 Div 2 area.

Thanks for your input.