How to select EPIC® SENSORS temperature sensors for potentially explosive (Ex) atmospheres?
ATEX protection 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).
When installed in an Ex i circuit the sensor itself has no need for ATEX/IECEx approval, if it has IP65 protection class and is 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, eg. from PR electronics (see figure below). In addition, the cable length must be chosen not to exceed the electrical data given in the certificate and data label of the circuit-supplying device.
The sensor is wired directly to an ATEX-approved electrical device in a safe (non-Ex) area.
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 electrical device in a safe (non-Ex) area.
ATEX protection Ex db and Ex tb
- ”db” stands for ”flameproof”, for Ex gas zones 1 or 2 (Ex db)
- ”tb” 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 db-construction, an Ex db-grade connection head, and possibly a temperature transmitter (PR5331A/D, PR5332A/N/D, PR5335A/D, PR5337A/D, PR5350A/B tai PR5437A/D). Also, other transmitter brands are possible, more info available in the certificate
- The measuring circuit can be cabled to a safe area and to a standard device (no Ex requirements).
A device installed in an Ex db enclosure has no ATEX/IECEx requirements, and therefore the transmitter can be a standard-type temperature transmitter for a safe area.
A measuring circuit extending outside the Ex db 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 a safe area or to a temperature transmitter.
ATEX protection Ex e and Ex tb
- ”e” provides ”increased safety”, for Ex gas zones 1 or 2 (Ex e)
- ”tb” 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 tb 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.
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.