Important
This ATEX Category depends on the application (see below) and also on the intrinsic safety level of the transmitter supply (associated apparatus) which can
sometimes suitably be [ib] instead of [ia]. As it is well known, the level of an intrinsic safety system is determined by the lowest level of the various apparatus
used, i.e., in the case of [ib] supply, the system takes over this level of protection.
The meaning of ATEX code is as follows:
II: Group for surface areas (not mines)
1/2: Category - It means that only a part of the transmitter complies with category 1 and a second part complies with category 2
(see next application sketch).
G: Gas (dangerous media)
D: Dust (dangerous media)
T85°C: Maximum surface temperature of the transmitter enclosure with a Ta from -50°C to +40°C for Dust (not Gas) with a dust
layer up to 50 mm depth.
T85°C: As before for Dust for a Ta +85°C
(Note: the number close to the CE marking of the transmitter safety label identifies the Notified Body which has responsibility for
the surveillance of the production)
The other marking refers to the protection type used according to relevant EN standards:
Ex ia: Intrinsic safety, protection level “a”
IIC: Gas group
T4: Temperature class of the transmitter (which corresponds to 135°C max) with a Ta from -50°C to +85°C
T5: Temperature class of the transmitter (which corresponds to 100°C max) with a Ta from -50°C to +40°C
T6: Temperature class of the transmitter (which corresponds to 85°C max) with a Ta from -50°C to +40°C
About the applications, this transmitter can be used in Zone “0” (Gas) classified areas (continuous hazard) with its “process part”
only, whereas the remaining part of the transmitter, i.e. its enclosure, can be used in Zone 1 (Gas), only (see sketch below).
Reason of this is the process part of the transmitter (normally called primary transducer) that provides inside separation elements
to seal off the electrical sensor from the continuously hazardous process, according to the EN 60079-26 and EN 60079-1. About
Dust application, the transmitter is suitable for “Zone 21” according to the EN 61241-0 and EN 61241-11 as it is shown on the
relevant part of the sketch:
Application for pressure transmitter Ex ia categories 1/2G and 1/2D
Zone “0” Zone “1”
Dangerous
medium
(process)
Tank
Zone “0” / Zone “1”
separation element
Primary transducer
Note: the transmitter can be con-
nected to either [ib] or [ia] supply
(associated apparatus)certified
[Ex ia]
Note for “Primary transducer”:
see the certification for
exceptions
Application with Gas Application with Dust
266 Tx
Category 1/2 G Ex ia
Zone “20” Zone “21”
Dangerous
medium
(process)
Silo
Note: the protection is mainly
assured by the “IP” degree associ-
ated to the low power from supply.
This can either be [ia] or [ib]
266 Tx
Category 1/2 D Ex ia
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