Enforcing EN12101-3 2015 Rules On High Temperature Smoke Extract Fans and Frequency Inverters

On occasion, the speed at which a fan’s smoke extract runs may need to be altered. This may be to facilitate a ‘boost mode’, whereby this extract rate is increased for fire-fighting purposes, to fine-tune the extract rate to meet the design criteria, or simply to reduce the extract rate when all doors are closed, to prevent over de-pressurisation of a space which could make it difficult to open the escape doors.

EN 12101-3 2015 permits the use of inverter drives to control smoke extract fans, but only in certain circumstances;

  1. Use of an inverter and a fan that are tested and CERTIFIED to operate together
  2. Use of the inverter for soft starting only, and then switching to Direct On Line (DOL) when the fan is running
  3. Use of an un-tested inverter and smoke extract fan when the fan motor is de-rated by 20% and suitable filters are fitted to the output to protect the fan motor insulation from unexpected temperature rise.

Option 3 results in additional equipment being installed, along with larger (and more expensive) fans and motors. Option 2 requires the use of additional control equipment within the control panel and, furthermore, when using DOL mode, it is not possible to control the speed of the fan, hence limiting the suitability of this application.

In our opinion, it would always be best to use a combination of devices that are not only tested together but tested and certified to operate together, as in option 1. And this is exactly what LYFE offer with our pre-assembled smoke extract packages.

Some manufacturers have suggested that the enforcing authority need to produce some specific guidance on how they intend to enforce the 2015 rules, but here at LYFE, our opinion is that we should not be asking how the rules intend to be enforced, but rather ask ‘how can I comply?’ It is only by changing the mindset to focusing on greater life protection at all times, rather than adhering to minimum requirements (and, at best, only when they are known to be enforced).

At LYFE, we see that greater life protection can be achieved by always specifying:

  • Smoke-control systems that are used to ground lifts and open access control doors
  • Smoke-control systems that are used to connect sprinkler flow switches
  • Extension of the fire detection & alarm systems from the common parts into the individual flats