KROHNE DK 46-47-48-800 ATEX II2G Ex i EN - Manual (Page 6)

2
DEVICE DESCRIPTION
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DK46 - DK800
www.krohne.com 08/2012 - 4000430903 AD DK46/800 II2G R04 en
2.4 Flammable products
Atmospheric conditions
An explosive atmosphere is defined as a mixture of air and flammable gases, vapours, mists or
dusts under atmospheric conditions with the values
T
atm
= -20°C...+60°C / -4°F...140°F and P
atm
= 0,8...1,1bar.
Outside of this range, no key data are available as to ignition behaviour for most mixtures.
Operating conditions
Variable area flowmeters operate outside of atmospheric conditions, which means that
explosion protection according to Directive 94/9/EC (ATEX) – regardless of the zone assignment
– is fundamentally not applicable due to the lack of key safety data for the interior of the
measuring unit.
2.5 Equipment category
The flowmeters are designed in Category II 2G according to EN 60079-0 and
EN 60079-11 for use in Zone 1.
2.6 Types of protection
The circuits of the limit switches (ring sensors) are designed in Intrinsic Safety type of protection
of Category ”ia“. They can also be operated in Category ”ib“.
CAUTION!
Operation with flammable products is only permissible if no explosive fuel/air mixture is formed
on the interior of the flowmeter under operating conditions. The user is responsible for the safe
operation of the flowmeter with regard to the temperatures and pressures of the products used.
In case of operation with flammable products the measuring units must be included in the
periodic pressure tests of the system.
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