DEVICE DESCRIPTION
2
7
DK37/M8 - H250/M8
www.krohne.com01/2016 - 4000760404 - AD DK37 M8 Ex II2G R04 en
2.4 Flammable products
Atmospheric conditions:
Atmospheric conditions:Atmospheric conditions:
Atmospheric conditions:
The ATEX directive does not stipulate values for atmospheric conditions. However, for
determining the explosion characteristic parameters of temperature and pressure range, the
following is assumed as a basis:
T
atm
= -20°C...+60°C / -4°F...+140°F and P
atm
= 0.8...1.1 bar / 11.6...15.9 psi
Outside of these ranges, for most mixtures no key figures are available for the ignition
behaviour.
Operating conditions:
Operating conditions:Operating conditions:
Operating conditions:
Variable area flowmeters operate outside of atmospheric conditions, which means that
explosion protection according to the ATEX directive –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 Device 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 variable area flowmeter is designed with type of protection intrinsic safety, level of
protection "ia" as per EN 60079-11.
The marking II 2G Ex ia IIC T6...T1 Gb
II 2G Ex ia IIC T6...T1 GbII 2G Ex ia IIC T6...T1 Gb
II 2G Ex ia IIC T6...T1 Gb contains the following information:
WARNING!
Operation with flammable products is only permitted as long as no explosive fuel/air mixture
builds up on the inside of the flowmeter under operating conditions. The operator is responsible
to ensure that the flowmeter is operated safely in terms of the temperature and pressure 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. When using the device version H250/C...
(PTFE version, non-conductive) the minimum conductivity of the media must be 10
-8
S/m, in
order to avoid danger from electrostatic charge.
II
IIII
II Explosion protection Group II
2
22
2Device category 2
G
GG
GGas explosion protection
ia
iaia
ia Intrinsically safe, level of protection "ia"
IIC
IICIIC
IIC Suitable for gas groups IIC, IIB and IIA
T6...T1
T6...T1T6...T1
T6...T1 Suitable for temperature classes T6 ...T1
Gb
GbGb
Gb EPL, suitable for zone 1 or zone 2
