3 min read

FM200 Fire Suppression Discharge

6 July 2018

What is FM-200 and how does fire suppression work in a data centre?

As a professional data centre operator, we utilise a variety of systems to ensure that your IT equipment is safe from the effects and potential damage caused by a fire.

As well as fire suppression, you can learn everything a data centre should provide by reading through our 'Data Centre Checklist'


Within our Byfleet data centre, we have a chemical based fire suppression system - FM200. This is a special fire extinguishing gas that removes the heat element of the fire triangle. You may have seen them around the data centre as big red cylinders.

FM200 Fire Suppression Discharge

FM200 is designed for data centres and means in the event of a fire occurring, it is extinguished extremely quickly - all without interruption to your services and no effect on your equipment.

An important component of the overall fire safety systems in a data centre is fire detection. These are the systems that make the decisions about the seriousness of an incident and whether to release the FM200 fire supressing gas.

Fire detection in a data centre consists of two main systems:

  • VESDA – Very Early Smoke Detection Apparatus. VESDA is constantly sampling the air to detect any minute particles of early stage combustion. Due to its sensitivity, should this system detect anything out of the ordinary, specially trained employees are able to quickly locate, identify and mitigate any potential risks before a full fire begins.
  • Ionising and Optical - We also have more traditional fire detection equipment, such as ionising and optical based detectors throughout the data centre. These are more traditional fire detectors such as those which you may find in offices or your home.

For the FM200 fire suppression gas system to release, we need to have entered a ‘double knock’ situation. This means that two independent ionising or optical sensors have detected something like a fire. This starts a 60 second countdown before the FM200 is released.

FM200 Fire Suppression Discharge

In normal operations the progression of the system works through five stages:

1. VESDA Pre-Alarm – if the system notices anything that could be the very early stage of a fire

2. VESDA Fire – the system detecting some particles that are certainly related to something combusting

3. Initial Knock – a traditional sensor has activated

4. Double Knock – at least one other sensor has activated

5. FM200 Release – the fire suppression gas is released

What happened on the 3rd July?

On Tuesday 3rd July, we experienced a component failure on a single FM200 cylinder that caused it to release its fire supressing gas and subsequently triggered an accidental discharge of the entire FM200 system.

Somewhat ironically,  this release of FM200 from the single failed cylinder was the cause of a Double Knock, activating three separate detectors, starting the countdown for the system to be activated and then releasing the FM200 from all the other cylinders. Due to the immediate activation of the Double Knock and countdown, the building was evacuated as per standard fire procedures once the Double Knock alarms are sounded.

Component failures and accidental discharges of a FM200 system are extremely rare with an estimated failure rate of 1 in 16 million for the components within the system. As a result we are still working with our specialist fire systems contractors to review any learning points on the root cause of the initial component failure, and will be sharing these through the industry due to the rarity of this type of incident.

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