ATEX sensors for hazardous areas

Intrinsically safe temperature sensors under our own certification — resistance thermometers and thermocouples, made in Hanau.

ATEX sensors measure temperature where flammable gases, vapours or dusts may occur: in chemicals and petrochemicals, painting and drying plants, mills, silos and spray booths. GHI manufactures intrinsically safe Pt100 resistance thermometers and type K, N and J thermocouples for zones 0, 1 and 2 as well as zones 20, 21 and 22. The EU type-examination certificate is issued to GHI — we mark our products ourselves, issue the declaration of conformity ourselves and do not depend on any subcontractor for the Ex version.

Our certification — and what it covers

GHI is itself an ATEX manufacturer. The EU type-examination certificate and the IECEx certificate are issued to GHI, and production is monitored by notified body 2004 (Bureau Veritas). The approval covers the WME and TME measuring inserts and the WML and TML sheathed sensors — on their own and installed in our thermowells and connection heads.

Not covered are flameproof enclosures (Ex d) and process temperatures above +450 °C. Tell us the zone, equipment group and temperature class and we will design the version.

Which version suits your zone?

Zone and installation determine the type of protection and the marking. Choose the row that matches your measuring point.

ATEX versions at a glance

Understanding ATEX — the basics in brief

Zones, equipment categories and EPL

The zone describes how often an explosive atmosphere occurs and thus determines which equipment category may be installed:

• Gas: zone 0 (continuous) → category 1G, EPL Ga · zone 1 (occasional) → 2G, Gb · zone 2 (rare, short-term) → 3G, Gc
• Dust: zone 20 → 1D, Da · zone 21 → 2D, Db · zone 22 → 3D, Dc
• Equipment for zone 0 may always be used in zones 1 and 2 as well, but not the other way round

Type of protection intrinsic safety: Ex ia and Ex ib

Intrinsic safety limits the energy in the circuit so far that neither a spark nor heating can cause ignition. Ex ia is approved for zone 0, Ex ib for zone 1. The sensor alone does not make the measuring point intrinsically safe: it must be connected to a certified intrinsically safe circuit, i.e. an isolating repeater, Zener barrier or transmitter with intrinsically safe input.

Reading the marking — example II 1/2G Ex ib IIC T4 Ga/Gb

Every symbol has a meaning, and this is exactly what the operator checks:

• II — equipment group for all areas except mining
• 1/2G — partition-wall installation: the tip is in zone 0, the connection head in zone 1
• Ex ib — type of protection intrinsic safety
• IIC — highest explosion group, includes hydrogen and acetylene
• T4 — temperature class: maximum surface temperature 135 °C
• Ga/Gb — equipment protection level inside/outside the partition wall

Intrinsic safety parameters and the verification

For verifying intrinsic safety, the sensor parameters are compared with the values of the isolating repeater: Ui 30 V, Ii 70 mA and Pi 500 mW apply as the total over all contacts — with two measuring elements, therefore combined, not per circuit. In addition, the cable-length-dependent values Ci 250 pF/m and Li 50 µH/m apply. On request we prepare the intrinsic safety verification to EN IEC 60079-11, section 5.7, as a test document for your records.

Temperature class and surface temperature

The maximum surface temperature results from ambient temperature and supplied power. For the dust zones the marking is T440 °C…T63 °C, with thermowell as a T₂₀₀value. The ambient temperature at the connection head may be between −40 and +85 °C, the measuring range of the sensor in the hazardous area between −50 and +450 °C.

Special conditions for safe use

The certificate carries the suffix X. Three points must be observed during installation and operation:

• For installation in a partition wall to zone 0 or 20, an additional thermowell is required
• The process connection must be leak-tight
• The metal housing must be earthed via the installation

What we do not offer

Being clear saves a query: our approval covers only the type of protection intrinsic safety “i”. We do not offer flameproof enclosures (Ex d), and the approval ends above +450 °C process temperature. As a rule we do not use third-party certificates — what is on our type plate is our own certificate.

What is supplied with the sensor

Every Ex sensor comes with a type plate with full marking, EU declaration of conformity and operating instructions. On request we add factory calibration with test report, inspection certificate and the intrinsic safety verification. Please state the required scope directly in your enquiry.

Approved and made in Hanau

GHI has been building temperature sensors since 1970 and manufactures at its Hanau site. Ex production runs under a quality assurance system monitored by Bureau Veritas, and the company is certified to ISO 9001. As a result, Ex versions add no extra lead time compared with the standard version.

Typical industries

Chemicals & petrochemicals Pharma & biotechnology Food & beverages Plastics & extrusion Energy, power plants & hydrogen Machinery & plant engineering

Please contact us

We are happy to help with questions about products, versions and delivery times.

Dennis Kühne
Phone: +49 6181 504 93 18
Mobile: +49 160 91437153
E-mail: info@ghi-gmbh.de