IEC 60079-29-1:2007/ISH1:2009

TC 31/Publication 60079-29-1 (2007), First edition/I-SH 01

EXPLOSIVE ATMOSPHERES –
Part 29-1: Gas detectors – Performance requirements
of detectors for flammable gases

INTERPRETATION SHEET 1
This interpretation sheet has been prepared by IEC technical committee 31: Equipment
for explosive atmospheres.
The text of this interpretation sheet is based on the following documents:
ISH Report on voting
31/809/ISH 31/817/RVD
Full information on the voting for the approval of this interpretation sheet can be found in
the report on voting indicated in the above table.
___________
There has been a request for formal interpretation of the drop test fail criterion in the
performance standard IEC 60079-29-1 (2007), Subclause 5.4.14.

The fail criterion is:
“The apparatus shall be considered to have failed this test if there is a loss of function
(e.g. alarm, pump function, controls, display) after the test”.

Question:
Is the interpretation of this text, that the loss of function, even in a short period during the
interruption and until restart of the equipment will fail the test? Or is a permanent loss of
function needed to fail the equipment, e.g. a broken display or a pump, which cannot
restart?
Bouncing of a battery spring in the moment of impact can cause the drop out of power in
battery supplied equipment, and make it shut down. Is this considered as sufficient to fail
the test? Or would it be sufficient safe situation for the user if the equipment could restart
and show the correct measurement?

Interpretation:
Any loss of function after the test including any change of state is considered a failure
since there is continued dependency on the life safety device even under adverse affects
such as an accidental drop of the device during use. Automatic or manual re-starting is
not acceptable.
CE 31/Publication 60079-29-1 (2007), Première édition/I-SH 01
ATMOSPHÈRES EXPLOSIVES –
Partie 29-1: Détecteurs de gaz – Exigences d’aptitude à la fonction
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