By BBC Northern corrrespondent Richard Wells

Imagine the scene. A house catches fire. Mercifully the occupants escape without injury. The fire brigade is called amid fears that the flames could spread to neighbouring homes and firefighters duly arrive to fight the blaze not with water but... a fan.

It sounds the stuff of madness. But in the Lancashire town of Preston, on Friday, Positive Pressure Ventilation, as the technique is called, is to be put to the test as a means of extinguishing fires.

A large portable fan, strapped to a fire engine, has been used by Lancashire Fire Brigade for some time to help mopping up operations after a fire.

Fans used to improve conditions

It rapidly clears heat and smoke from buildings where a fire has already been put out using conventional hose and water or chemicals. Working conditions for firefighters are improved immediately.

Friday's experiments take that technique one very important stage further using the fan during a blaze.

Lancashire Fire and Rescue Service says its research has shown that use of the fan should blow away the products of combustion, such as smoke, fire gases and heat, without fanning the flames with potentially dangerous oxygen.

The effect is to save wastage of a much valued resource - water - and reduce damage to gutted buildings, a boon to victims and insurance companies.

21st century firefighter

It is this research that is being put to the test in a street in Preston which is awaiting demolition.

Unwanted furniture and bedding will be taken into rooms in derelict terrace houses and set ablaze. Firefighters will use the fan, tactically and offensively, to see how it copes.

Firefighters are hopeful that the carefully regulated house fires will be blown out successfully.

Monitoring equipment will help inform experts whether the fan could have a pivotal part to play in the 21st century fire brigade.

But the old fashioned hose, complete with water, will be on stand-by... just in case.