Emerson Edition 4 Manuel D’Utilisation

Chapter 2 Safety

308014EN, Edition 4
May 2013

Rosemount TankRadar REX equipment is often used in areas where 
flammable materials are handled and where an explosive atmosphere 
may be present. To protect both the plant and the personnel, precautions 
must be taken to ensure that this atmosphere cannot be ignited. These 
areas are called hazardous areas and equipment within these areas 
must be explosion protected. 

A number of different explosion protection techniques have been 

developed over the years. Intrinsic safety and explosion proof (or flame 
proof) safety are two techniques. 

Intrinsic safety, IS, is based on the principle of restricting electrical 
energy available in hazardous-area circuits such that any sparks or hot 
surfaces, that may occur as a result of electrical faults in components, 
are unable to cause ignition. Intrinsic safety is the only technique 
accepted for Zone 0 hazardous areas. It is also safe for personnel and 
allows equipment to be maintained without the need for a gas-free 
certificate. 

For example, temperature measurement with the DAU is intrinsically 
safe. 

The basic principles of intrinsic safety are: 

•

All flammable materials are grouped according to the energy 

needed to ignite them. 

•

Equipment located in hazardous areas are classified according to 
the maximum surface temperature that it can produce and this 
must be safe with the flammable gases that may be present. 

•

Hazardous areas are classified according to the probability that an 
explosive atmosphere is present, and this dictates whether or not 
a particular explosion protection technique may be used.