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Old November 24th, 2017, 03:45 AM   #1
DLMUK
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ATEX Intrisic Safety (IS) question.

Hi,

I have an application which is in an ATEX hazardous area, the instrument being used is lower power and qualifies as 'simple apparatus' and is connected from the safe area via an IS barrier.

The setup is:

Instrument -> cable -> barrier -> safe zone

What I would like to know is, if we put a connector on the cable half way down its length, but within the hazardous area, does it require and ATEX approval?

As the power is limited by the barrier before the connector, I can see an argument that the connector type doesn't matter. I have also seen applications where both ATEX and non ATEX connectors are used.

thanks
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Old November 24th, 2017, 04:30 AM   #2
Rob...
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What type of connector? Just terminals?

Are you altering the characteristics of the loop? E.g adding any capacitance/impedance?

I'd be wary with calling items 'simple apparatus' unless certified as such by the manufacturer. To certify yourself you need to prove it meets around 7 BS EN Standards. Some of which needs lab testing to verify.
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Old November 24th, 2017, 04:36 AM   #3
DLMUK
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@Rob

thanks for the reply. The item has already been confirmed as Simple Apparatus by an authorized UK test house.

What we want to do is just add a connector to help with installation and maintenance. So that the instrument can be easily removed for calibration. It would therefore be an inline cable end connector, one male and female receptacle.

We haven't specified a connector as unsure what is required at present. Something along these lines would be good:

https://uk.rs-online.com/web/p/mil-s...ctors/2982409/

thanks
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Old November 24th, 2017, 04:50 AM   #4
Rob...
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I would think that as it has been passed through a barrier you're ok using something like that. I'll have to check though.

Regulations will most likely stipulate that it can't be plugged or unplugged whilst the circuit is energized.
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Old November 24th, 2017, 07:22 AM   #5
cardosocea
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You will still require that the plug conforms to the IP rating for that particular area (or perhaps it's fixed for IP65).

And the distances to the 3mm to earth and 6 between different loops.

Most likely and to err on the side of caution, anything Exe will do. I would also try to find a connector with an end cap to protect the terminals if the sensor is to be removed and not replaced. I don't think it is required, but can protect you concerning the condition of the loop.

I would also have a quick look on the rating for dust as the conditions compared to gas and vapours are different.
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Old November 25th, 2017, 04:54 AM   #6
Friedrich
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As stated by Rob there shouldn't be a problem as long as you don't add impedance or capacitance to the circuit, which you don't if the connector is just that. The connector doesn't need to be Atex approved since it's part of the IS loop. Just make sure you document it in you IS system description for that circuit.
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Old November 25th, 2017, 08:04 PM   #7
James Mcquade
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DLMUK,

if by connector, you are referring to terminal block, it depends on the environment.
if by connector you mean a micro connector, it still depends on the environment.

what ever the environment, you must use a seal off within 18" of the safe zone. the seal off being in the hazardous area. Rigid pipe, myers hubs, and conductive sealant ( not sure on this in the UK) as well.

the terminal block or connector must also meet certain criteria. I do not know the current UK rules, so please check.

cheers,
james
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