Hazardous areas



Within chemical, petroleum and technical industry there is ex-rated and flammable environments. Depending on the substances which are considered to make up the risks and the extent of their occurrence, these areas has been divided into zones.

Zone 0 – Constant presence of explosive substances.
Zone 1 – Temporary presence of explosive substances at normal operation.
Zone 2 – Occasional presence of explosive substances (not present during normal operation).

For the zone grouping there is determined norms. The authority that can be asked at uncertainty regarding work and zone groups and material allowed to be used is “Sprängämnesinspektionen (Inspection for explosives)”. To make installation work easier, there is on the most industries a rating map. This map informs about the different zones present within the industrial surface. In the case a map is not available a judgement of the area must be carried out.

Explanation of zone division

Zone 0
There it always is a risk of explosion. This is found inside tanks, cisterns and in pump rooms and such spaces where fluids, easily set on fire and gases are expected to be present continuously.

Zone 1
Here an explosive risk at for example reloading, fillings, valves and at taps of fluids, easily set on fire and gases, valves etc.

Zone 2
areas except zone 1 within an Ex-area.

As a complement to the zone division, is temperature- and gas group classification. According to the Cenelec norm (Cenelec stands for Comite Europeen de Normalisation Electrotechnique) it is decided upon following temperature classes

Class Max. temperature Gas group identification
T1 Över 450°C
T2 300°C
T3 200°C
T4 135°C IIA
T5 100°C IIB
T6 85°C IIC

The temperatures which are stated in the table is the maximum temperatures which may be present on the material, for example heating cable which may be used at an ambient temperature of 40°C.

Special attention is directed against group II C (hydrogen). 2 H2O2 2 H2O + O2.

If two gas groups are mentioned in the same specification, for example II B and II A, the whole surface is rated as II B.

All equipment, which shall be installed in an Ex-rated surface, must meet the sealing class, which are prescribed for the zone.

Below is a list over the symbols that are used:

Exe Increased safety
Exd Inflammable
Exp Pressure adapted
Exs Special protection
Exm casted design
Exo Filled with oil
Exi Interior safety
Exq Filled with sand

Description of the norms is available in Europanormer EN-50014-50020

EX material



Products can be approved in accordance with local regulations or European norms. The European norms is marked with an extra E in front of the Ex symbol.


Exd IIB T6
Flamsäkerhet till lokala normer Gasgrupp Temperaturklass
Eexd IIB T6
Flamsäkerhet till Europeiska normer Gasgrupp Temperaturklass

Fortfarande finns det länder vars normer ej harmoniseras/överensstämmer. Länders provningsmyndigheter har olika tolkningar av normerna. Värmekabel är fortfarande en öppen fråga i många länder. Detta innebär att det i Belgien eller England kan vara möjligt att använda en kabel, som sedan inte accepteras i Tyskland eller Sverige och tvärtom.

Provningsmyndigheter som finns är:

Holland Tyskland Sverige
INIEX P.T.B Intertek (Semko)
Norge Danmark Finland

Vid sidan om flamsäkerhetstesten finns även elektriska och mekaniska tester på t.ex. isoleringstjocklek i temperaturklassen, temperaturbeständighet i skärm, värme från kabeln, mantling, draghållfasthet, böjlighet, böjtålighet, temperaturtålighet etc. Dessa tester kan utföras av:


Exd IIB T6
Flame proof to local standards Gas group Temperature class
Eexd IIB T6
Flame proof to European standards Gas group Temperature class

There are still countries which norms not is harmonic/corresponding. The testing authority of the different countries has different interpretations of the norms. Heating cables are still an open question in many countries. This implies that for example in Belgium or in England can be possible to use a cable, which is not accepted, in Germany or in Sweden and in contrary.

Testing authorities available are:

Netherlands Germany Sweden
INIEX P.T.B Intertek (Semko)
Norway Denmark Finnland

Except from the flame-proof tests there is also electrical and mechanical tests on for example the thickness of the insulation in the temperature class, heat- and cold resistance in the screen, heat from the cable, sheathing, tensile strength, flexibility, bending strength, temperature strength etc. These tests can be carried out by:

Netherlands Germany Sweden
Intertek (Semko)
SP – Statens Provningsanstalt i Borås
Norway Denmark

SS EN 60529

First number: Protection against contact and penetrating objects.
Second number: Protection against fluids
0 1 2 3 4 5 6 7 8
 0  IP00  –  –  –  –  –  –  –  –
 1  IP10  IP11  IP12  –  –  –  –  –  –
 2  IP20  IP21  IP22  IP23  –  –  –  –  –
 3  IP30  IP31  IP32  IP33  IP34  –  –  –  –
 4  IP40  IP41  IP42  IP43  IP44  –  –  –  –
 5  IP50  –  –  –  IP54  IP55  –  –  –
 6  IP60  –  –  –  –  IP65  IP66  IP67  IP68
umber: degree of protection against contact and penetrating of fixed objects. Second number: Degree of protection against penetrating fluids.
  1. No Protection against penetrating objects.
  1. No Protection
  1. Protection against contact of dangerous parts with the backside of the hand or object with a diameter larger than 50mm.
  1. Protection against vertical falling water drops.
  1. Protection against contact of dangerous parts with a finger or fixed objects with a diameter larger than 12mm.
  1. Protection against vertical falling water drops when the sealing inclines max. 15°.
  1. Protection against contact of dangerous parts with tools or fixed objects with a diameter larger than 2.5mm.
  1. Protection against sprinkling water.
  1. Protection against contact of dangerous parts with wire or fixed objects with a diameter larger than 1mm.
  1. Protection against sprinkling.
  1. Protection against contact of dangerous parts with wire. Dust guard.
  1. Protection against water jets.
  1. Protection against contact of dangerous parts with wire. Dust guard.
  1. Protection against heavy water jets.
  1. Protection against influence at short immersion in water.
  1. Protection against influence of long immersion in water.

When you choose material to an application you shall make sure that the IP-rate of the chosen material at least corresponds to the zone class available for the area or as in description stated class for the application.