Ex P Pressurised Enclosure – What is it and how is it useful

Ex P Pressurised Enclosure is an explosion protection mechanism used in hazardous locations. Ex P enclosures are designed to house electrical equipment that is either too large to be made explosion proof or too highly powered. Industries with complex processes such as chemical, pharmaceutical, oil and gas industries, refineries, and paint manufacturing units that use and store highly flammable gases and vapours require a safe, durable, low-cost solution for operating electrical equipment and yet create an explosion free zone. This is where Ex P enclosures come into the picture.

Where is an Ex P enclosure used?

Ex P enclosures are commonly used in industries or environments that have an explosive atmosphere. An explosive atmosphere consists of a mixture of gases, vapours, and dust in the air that are flammable and cause ignition and thereby explosion. The ATEX European Union Directive classifies and controls the Explosive atmosphere. Our article – A complete guide to ATEX certification – explains these classifications in detail. A variety of protection concepts are used in these hazardous areas, Ex P pressurised enclosures being one of them. You can learn about protection concepts from our article on Concepts for protection of hazardous areas.

How do the enclosures work?

These pressurized enclosures look like large cabinets which are tightly sealed so that explosive gases cannot enter the chamber, and electrical equipment that are non-explosion proof can be safely operated. An Ex P enclosure consists of:

  • A control unit
  • Ex P pressure monitors
  • Ex P purge valves

First, the enclosure is purged or cleansed with ignition protection gas. This helps dilute the combustible gas mixture and thereby create an explosion free zone. Next overpressure is created so that explosive gases cannot make their way into the enclosure. The Purge valves inside the Ex p enclosures help control and transport the ignition gases, whereas the temperature monitoring system ensures adequate cooling. A number of equipment such as industrial monitors, motors, pumps and switch gears can safely be operated within the Ex P enclosures.

Since purging and pressurising are integral parts of these enclosures, they have been assigned the nomenclature Ex P pressured enclosures – P standing for purge. 

Though durable and reliable, proper care should be taken during the installation and operation of these enclosures. They should be properly sealed so that the chances of leaks are minimized. 

Also, the enclosures should be designed keeping in mind their environment. Can they withstand rain and snow? Are the enclosures exposed to salt water or other chemicals? What are the thermal conditions and what’s the temperature inside and outside the enclosures? Are they exposed to extreme temperatures? What light fixtures are used here and do they meet the industry standards for explosion proof lighting? These are some of the questions that need to be asked before using Ex P enclosures in a hazardous environment.

Main Features of Ex P Enclosures

  • They can be certified as per ATEX and IECEx standards.
  • The design of all enclosure joints should comply with established standards.
  • No external hot surfaces above the temperature class.
  • All plastic components should undergo high temperature and humidity testing.
  • Sparking contacts, semiconductor devices, batteries and rotating parts can be fitted within an enclosure.

Advantages of using Ex P pressured enclosures

Using Ex P pressurised enclosures can provide a range of benefits, some of which are:

  1. They are robust with high longevity (as much as 15 years) and are very user-friendly. 
  2. They are available in a variety of sizes and hence can be commercially and non-commercially used. 
  3. They are lighter than other protection methods. For example, while a typical Ex D enclosure may weigh around 180 Kilograms, an Ex P enclosure weighs around 40 Kilograms. 
  4. These enclosures can be easily opened, which not only makes maintenance easy but also helps in quick response during emergencies. 
  5. They are cost-effective since a single unit can purge multiple enclosures in a series. This enables the replacement of multiple explosion proof boxes and interlinking conduits. 
  6. The purge and pressurised enclosures can be easily reconfigured and upgraded as per requirement. 

When it comes to performance, there is no limitation for Ex P enclosures. It is largely dependent on the size of the Ex P cabinet or the Ex P application. Ex P applications are hosted inside enclosures which are closed and sealed. All power dissipation and heat flows must be removed. Air conditioning systems can be used for this purpose. Also, components must be fitted at a distance from each other to prevent damage from high voltages and currents. 

When it comes to safety in hazardous areas, Ex P pressurised enclosures are a good option. We have a range of certified products fitted with this mechanism suitable for a variety of facilities. Check out our Product Portfolio today to browse them.