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Topic Title: IIC equipment rating, IIB hazard, barrier gland required?
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Created On: 17 June 2014 03:03 PM
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 17 June 2014 03:03 PM
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camaraneo

Posts: 3
Joined: 17 June 2014

Hi,

We have a number of pressure switches rated as follows:
Equipment group II
Equipment category 2GD
Type of protection EEx d
Gas group IIC

The requirements of the area the switches are to be installed in are:
Zone 1
Gas group IIB

The switch enclosures are far smaller than 2 litres volume.

The CompEx handboox, section 6.5 , table 11 details the barrier gland requirements, with one of the column headings being " 'Gas' group required".

[ETA: Toolbox Guide, EEMUA pub. 214, 5th ed.]

Does this apply to the area the item is to be installed in, or to the certification of the equipment?

According to the table:
Zone 1, Gas gp. IIB, & less than 2l
No barrier gland required

However, if gas gp. IIC, barrier gland required.

So it comes down to whether the column refers to the certification of the equipment, or the area of installation.

Anyone able to clarify? A reference would be ideal, to settle any argument!

Thanks,
Cam

Edited: 17 June 2014 at 03:27 PM by camaraneo
 18 June 2014 03:44 PM
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oneye

Posts: 177
Joined: 25 February 2008

I do not believe the corollary of your point reduces to:
'So it comes down to whether the column refers to the certification of the equipment, or the area of installation'.
As my answer would be the area of installation without any further qualification.

I cannot locate your references and it is unclear exactly the intention - so am assuming you would have armoured cable terminating into an EExd rated switch.

Would you terminate this cable into the switch without any form of gland ? This would appear alomost as bad as cabling into the switch using metal conduit; and have seen such an installation.


The ATEX directives 94/9/EC and 99/92/EC with new Directive 2014/34/EU apply.
(chart e.g. http://www.atexglobal.com/atexdirective-94-9-EC.pdf)

I suggest you would use a flameproof gland of suitable type and size for both switch and cable.
(e.g. http://www.etscc.co.uk/hawke-cable-glands)
 18 June 2014 05:32 PM
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chartassuk

Posts: 57
Joined: 25 July 2008

Hi Cam,

One other element required from both Zone assessment and pressure switch - T Class - find that out please.

This will determine whether the device is suitable for installation in the Hazardous Area.

Next, look at the ATEX certificate for the pressure switch - are there any X conditions (special conditions for use)? - find that out please.

The EEMUA toolbox guide 214 edition 5 states a couple more important factors:

Is the cable type round, compact and with extruded bedding? (i.e. SWA or GSWB, not a loose cable such as YY/CY/SY)

Does the pressure switch contain an internal source of ignition? (i.e. any energy storage components, or contacts that are able to produce a spark)

These further pieces of information will help inform you on gland selection.

You should also read up on BSEN60079-1 (Ex d), and -14 (installations).
 18 June 2014 07:47 PM
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camaraneo

Posts: 3
Joined: 17 June 2014

I first need to apologise - I was getting mixed up, the unit is not a pressure switch, but a thermostat, switching 230Vac, and there is an internal source of ignition.

Supply cable is armoured, YD303 (fire resistant, 3 core 2.5mm) - round, compact, extruded bedding, no cold flow).

Sorry, I didn't specify that the current gland is a Hawke 501/453/Universal EEx d. This is not a barrier gland, but an elastomeric seal type.

The only special condition that applies for the device is "the calorific transfer of the sensor shall not transmit, in any case a heating above 80 deg C, including ambient temperature, to all thermostat part directly in contact with explosive atmosphere." (LCIE cert translated from French)

There is no doubt whatsoever about the device's suitability for the area, or for the intended service, and the section of EEMUA 214 I am asking about does not reference the T class... But the area requirements are T3, device is T6

The only question is whether a barrier gland is needed in place of the non-barrier gland in use now.

Since the area of installation is Zone 1 gas group IIB, the enclosure is les than 2l volume, and the cable is round, compact, extruded bedding, I believe a barrier gland is not required.

However, I have a guy arguing that the table refers to the classification of the device, which is good for gas group IIC, and in this case the barrier gland would be required.
 19 June 2014 10:45 PM
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chartassuk

Posts: 57
Joined: 25 July 2008

Thanks for supplying additional info.

'Guy' is wrong; the circuit has to be installed to meet the environment, and the environment is:

Z1 IIB T3

The fact that the device rating exceeds the environment requirement is pretty common as it's more cost effective (and less installation error inducing) for a manufacturer to make equipment to meet a more onerous set of criteria. ATEX certification carried out once for a hypothetical 1G (Z0) IIC T6 device is definitely cheaper than ATEX certification for each of 1G/2G/3G, IIA/B/C, T1-T6! Sorry these are now EPLs of Ga/Gb/Gc..

If the the environment was a Z2 IIA T1 and the device was a Ga IIC T6, would we go to the expense, time and effort of using barrier glands? No, of course not.

In summary, you have followed guidance correctly for the environment, device rating, cable type, energy potential and volumetric limit for the device within this circuit, so a non-barrier Ex d gland is appropriate.

I would also question the last time 'guy' had his CompEx refresher..
 20 June 2014 12:47 PM
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camaraneo

Posts: 3
Joined: 17 June 2014

Thanks chartassuk, it's always good to get some backup.
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