EPL (Equipment Protection Level) according to IEC/EN 60079-xx series of standards

Definition:

The level of protection assigned to equipment based on its risk of becoming a source of ignition, and distinguishing the differences between explosive gas atmospheres, explosive dust atmospheres, and the explosive atmospheres which may exist in coal mines

Link between Zones, Atex categories and EPL:

Area towards Equipment

Why EPL (Atex categories)

Historically it has been acceptable to install equipment into specific zones based on the type of protection.

In som cases it has been showen that the type of protection may been divided into different levels of protection that can be correlated against each Zone. A better risk assessment would consider all factors. When using a risk assessment approach instead  of the inflexible approach of the past linking equipment to Zones the inherent ignition risk of the equipment is clearly indicated, no matter what type of protection is used.

An example using a risk assessment approach:

Plant operators often make intuitive decisions on extending (or restricting) their Zones in order to compensate for this inflexibility. A typical example is the installation of "Zones 1 Type" navigation equipment in Zone 2 areas of offshore oil production platforms, so that the navigation equipment can remain functional even in the presence of a totally unexpected and prolonged gas release. On the other hand, it is reasonable for the owner of a remote, well secured, small pumping station to drive the pump with a "Zone 2 Type" motor, even in Zone 1, if the total amount of gas available to explode is small and the risk to life and property from such as explosion can be discounted.

The situation became more complex with the publication of the first edition of IEC 60079-26 which introduced additional requirements to be applied for equipment intended to be used in Zone 0. Prior to this, Ex ia was considered to be the only teqhnique acceptable in Zone 0.

It has been recognized that it is beneficial to identify and mark all products according to their inherent ignition risk. This makes equipment selection easier and a risk assessment approach, more appropriate.