DEVICE DESCRIPTION
2
9
DK37/M8 - H250/M8
www.krohne.com
11/2017 - 4002616802 - AD DK37 NEPSI Ex ia R02 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...+60
°
C / -4...+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
Variable area flowmeters are designed in accordance with GB 3836.1-2010 and GB 3836.4-2010
for use in zone 1.
The inside of the measuring unit is also approved for zone 1.
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.
INFORMATION!
Definition of zone 1:
An area in which an explosive atmosphere, as a result of the mixture of flammable substances in
the form of gas, steam or mist with air, under normal operation may occasionally occur.
