Selecting temperature sensors for
explosive (Ex) atmospheres
24.11.2015
1(5)
Selecting temperature sensors for potentially explosive (Ex) atmospheres
SKS Automaatio Oy's product range meets various temperature measurement needs in
potentially explosive atmospheres. The company's range covers temperature measuring
sensors, temperature transmitters, barriers, cables, cable glands, displays, alarm
devices, enclosures and lights. SKS Automaatio Oy is a part of the SKS Group.
The SKS Group has been granted an ATEX Quality Assurance Notification (VTT 02
ATEX Q001) as required under EU directive 94/9/EC. The notification, issued by VTT
Expert Services Ltd, gives the right to manufacture Ex e and Ex t temperature sensors
and to assemble Ex d temperature sensors for use in explosive atmospheres.
The SKS Group's sensor manufacturing operations have been assessed in an IECEx
Quality Assessment Report (FI/VTT/QAR14.0001/01) as required by the EN ISO/IEC
80079-34 standard. The auditing organization was VTT Expert Services Ltd. The report
gives the right to manufacture Ex e, Ex t and Ex d temperature sensors for use in
explosive atmospheres and to apply for IECEx approval for them.
You can choose from three Ex types of protection when selecting SKS Sensors®
temperature sensors manufactured by the SKS Group:
Ex i or I.S.
- ”i” or ”I.S.” provides ”intrinsic safety”.
- Designed for Ex zones 0, 1, 2, 20, 21 or 22.
- The sensor is a standard-type RTD or TC temperature sensor (no ATEX/IECEx requirements).
- The connection hood is a standard-type, IP 65-protected hood, with a protective earth
connection screw (no ATEX/IECEx requirements).
- The whole circuit must be designed as an intrinsically safe Ex i circuit (cable length,
ATEX/IECEx transmitters, ATEX/IECEx barriers).
- More details on page 2
Ex d, Ex t
- ”d” stands for ”flameproof”, for Ex gas zones 1 or 2 (Ex d).
- ”t” stands for ”protection by enclosure”, for Ex dust zones 21 or 22 (Ex tb).
- The sensor is ATEX and/or IECEx-certified, and consists of a Pt100 or TC sensor element
specially adapted for Ex d-construction, an Ex d-grade connection head, and possibly a
temperature transmitter (types PR5331A/D, PR5335A/D, PR5337A/D or PR5350A/B). The
enclosure is dust-protected (Ex t).
- The measuring circuit can be cabled to a safe area and to a standard device (no Ex
requirements).
- More details on page 3
Ex e, Ex t
- ”e” provides ”increased safety”, for Ex gas zones 1 or 2 (Ex e).
- ”t” stands for ”protection by enclosure”, for Ex dust zones 21 or 22 (Ex tb, former Ex tD A21).
- The sensor is an ATEX and/or IECEx-certified, Ex e-type, Pt100 or TC sensor, which can also
be used for dust areas, thanks to its dust-protected Ex t enclosure.
- The measuring circuit can be cabled to a safe area and to a standard device (no Ex
requirements).
- Our currently certified types are cable sensors, without a connection head.
- Our sensors can be manufactured with Ex e-grade connection heads, which makes them new
types that must be individually certified.
- More details on page 4
Selecting temperature sensors for
explosive (Ex) atmospheres
24.11.2015
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Ex i (I.S.)-type SKS Sensors® temperature sensors
The standard types of SKS Sensors® temperature sensors made in Finland are either
RTD (mainly Pt100) or TC (e.g. K, J or S type) sensors. Both are considered to be simple
electrical devices that can be installed in potentially explosive atmospheres, without Ex
approvals or Ex markings.
When installed in an Ex i circuit the sensor itself has no ATEX/IECEx approval
requirements, as long as it is IP65 ingress-protected and equipped with a separate ground
terminal. The whole circuit is intrinsically safe (I.S.) only when the sensor's outgoing
measuring circuit is connected to an I.S.-approved device outside the Ex area. The I.S.approved device can be an Ex temperature transmitter of, for example, PR Electronics
Inc. (see figure below). In addition, the cable length must also be engineered so as not to
exceed the electrical data given in the certificate and data label of the circuit-supplying
device.
Ex II (1) GD
3- or 4-wire
Ex
Ex II 1 GD
Ex ia IIC T4…T6 Ga
Ex ia IIIC Da
[Ex ia] IIC
PR
5131B
R/I
SKS Pt100
IP 65
non-Ex
2-wire
PR
5333D
R/I
2-wireoutput
mA
Ex II (1) GD
PR
5116B
I/I
SKS Pt100
IP 65
[Ex ia] IIC
supply
mA or V
relay output
Ex
non-Ex
Figure: Two examples of Pt100 temperature sensor solutions:
-
Upper part of the figure: the sensor is wired directly to an ATEX-approved,
associated electrical apparatus in a safe (non-Ex) area.
-
Lower part of the figure: the sensor is connected to an ATEX-approved, I.S. 2-wire
transmitter installed in a connection head, in which the transmitter's mA output signal
is wired to an ATEX-approved, associated electrical apparatus in a safe (non-Ex)
area.
Selecting temperature sensors for
explosive (Ex) atmospheres
24.11.2015
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Ex d / Ex t-type SKS Sensors® temperature sensors
Temperature sensors manufactured by the SKS Group can be assembled with an Ex dapproved connection head. The sensor element part is a replaceable RTD or TC probe
specially adapted for Ex d-construction (a standard element is not fit to be used in Ex dconstruction), while the connection head is Ex d-classified and equipped with cage
clamp terminals or a 2-wire temperature transmitter (the approved transmitter types are
PR5331A, PR5335A, PR5337A, PR5350A, PR5331D, PR5335D, PR5337D and
PR5350B). This assembly is ATEX Ex d-approved by product certificate (VTT 12 ATEX
055X) where X means that the cable gland can be chosen according to the temperature
class.
Device installed in an Ex d enclosure has no ATEX/IECEx requirements, and therefore
the transmitter can be a standard-type temperature transmitter for a safe area (see
figure below).
Ex II 2 GD
Ex d IIC T5/T6 Gb
Ex tb IIIC T80/T95 Db
non-Ex device
PR
5331A
2-wire mA
PR
5116A
SKS W-…Exd
or
SKS T-…Exd
supply
mA, V or/and
relay output
Ex
non-Ex
+PR transmitter
A measuring circuit extending outside the Ex d enclosure has no ATEX/IECEx
requirements for the next device outside the Ex area. The signal can be wired to a
standard-type signal converter in the safe area (see figure above) or to a temperature
transmitter (see figure below).
non-Ex device
Ex II 2 GD
Ex d IIC T5/T6 Gb
Ex tb IIIC T80/T95 Db
2-, 3- or 4-wire
SKS W-…Exd
or
SKS T-…Exd
Ex
PR
5131A
R/I
non-Ex
ATEX/IECEx-approved, Ex d-type sensor
Approval data
SKS W-…Exd or SKS T-…Exd
VTT 12 ATEX 055X Issue1
- RTD or TC sensor element adapted for Ex d-construction
- inside enclosure: terminals or temperature transmitter
(PR5331A/D, PR5335A/D, PR5337A/D or PR5350A/B)
- installation and connection according to datasheet
Ex II 2 G Ex d IIC T5/T6 Gb,
Ex II 2 D Ex tb IIIC T80/T95°C Db
2-wire
output
mA
Selecting temperature sensors for
explosive (Ex) atmospheres
24.11.2015
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Ex e / Ex t-type SKS Sensors® temperature sensors
The SKS Group also produces Ex e-type temperature sensors, which are ATEX and/or IECExcertified.
An Ex e-approved sensor's measuring circuit has no ATEX/IECEx requirements for the next
device outside the Ex area. The signal can be wired to a standard-type temperature
transmitter in a safe area, for example (see figure below).
Ex II 2 GD
Ex e IIC T6…T3 Gb,
Ex tb IIIC T60..T200°C Db
2- or 4-wire
PR
5131A
R/I
non-Ex device
SKS Pt100-EX
Ex
2-wire
output,
mA
non-Ex
Ex e-type sensors and their product certificate data are presented on the next page.
Visit www.skssensors.com/en/industry-sectors/explosive-areas/
Selecting temperature sensors for
explosive (Ex) atmospheres
24.11.2015
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Ex e / Ex t-type SKS Sensors® temperature sensors
Ex e-type sensors
Approval data
1059616, WT-BAJONETTI-6/XXX-YYYY/TDT-4J-KLA-EX
VTT 14 ATEX 005X
IECEx VTT 14.0003X
- Pt100 bayonet sensor, 4-wire, 6 mm diameter
- produced on request
- approval permits only dimensions XXX and YYYY to be altered
1059620, 2xWT-BAJONETTI-8/XXX-YYYY/TDT-4J-KLA-EX
- 2xPt100 bayonet sensor, 4-wire, 8 mm diameter
- produced on request
- approval permits only dimensions XXX and YYYY to be altered
1061957, WT-KAAPELI-6/XXX-YYYY/TDT-4J-KLA-EX
- Pt100 cable sensor, 4-wire, 6 mm diameter
- produced on request
- approval permits only dimensions XXX and YYYY to be altered
Ex II 2 G Ex e IIC T6…T3 Gb
Ex II 2 D Ex tb IIIC T60°C…T200°C Db
VTT 14 ATEX 005X
IECEx VTT 14.0003X
(X = temperature limits)
Ex II 2 G Ex e IIC T6…T3 Gb
Ex II 2 D Ex tb IIIC T60°C…T200°C Db
VTT 14 ATEX 004X
IECEx VTT 14.0002X
(X = temperature limits)
Ex II 2 G Ex e IIC T6…T3 Gb
Ex II 2 D Ex tb IIIC T60°C…T200°C Db
1061958, WT-KAAPELI-6/XXX-YYYY/SDS-2J-KLA-EX
VTT 07 ATEX 012X
- Pt100 cable sensor, 2-wire, 6 mm diameter
- produced on request
- approval permits only dimensions XXX and YYYY to be altered
Ex II 2 GD Ex e II T1-T6
Ex tD A21 IP66 T60°C
Tamb(max) +180°C
1061961, 2xWT-KAAPELI-6/XXX-YYYY/TDT-4J-KLA-EX
VTT 14 ATEX 004X
IECEx VTT 14.0002X
- 2xPt100 cable sensor, 4-wire, 6 mm diameter
- produced on request
- approval permits only dimensions XXX and YYYY to be altered
(X = temperature limits)
(X = temp., voltage)
(X = temperature limits)
Ex II 2 G Ex e IIC T6…T3 Gb
Ex II 2 D Ex tb IIIC T60°C…T200°C Db
1068685, WT-MI-302-6/XXXXX-200/FEP-4J-KLA-EX
VTT 07 ATEX 013X
- MI sheath structured Pt100-element, 4-wire, 6 mm diameter
- produced on request
- approval permits only dimension XXXXX to be altered
Ex II 2 GD Ex e II T1-T6
Ex tD A21 IP66 T60°C
Tamb: -40…+125/550°C
1125387, WT-MI-302-3/1000-200/FEP-4J-KLA-EX
VTT 07 ATEX 014X + SUPPLEMENT 1
- MI sheath structured Pt100-element, 4-wire, 3 mm diameter
- sensor part length 1 m
- approval permits no values to be altered
Ex II 2 GD Ex e II T1-T6
Ex tD A21 IP66 T60°C
Tamb: -40…+125/550°C
1073428, WT-MI-302-6/1000-200/FEP-4J-KLA-EX
VTT 07 ATEX 014X
- MI sheath structured Pt100-element, 4-wire, 6 mm diameter
- stocked, sensor part length 1 m
- approval permits no values to be altered
Ex II 2 GD Ex e II T1-T6
Ex tD A21 IP66 T60°C
Tamb: -40…+125/550°C
1072372, WT-MI-302-6/2000-200/FEP-4J-KLA-EX
VTT 07 ATEX 015X
- MI sheath structured Pt100-element, 4-wire, 6 mm diameter
- produced on request, sensor part length 2 m
- approval permits no values to be altered
Ex II 2 GD Ex e II T1-T6
Ex tD A21 IP66 T60°C
Tamb: -40…+125/550°C
www.skssensors.com
(X = temp., voltage)
(X = temp., voltage)
(X = temp., voltage)
skssensors@sks.fi