LEADER GROUP UK LTD

Over the past three months 46 Fire Officers representing 27 UK Fire Brigades have visited the scientific research facility based at the University of Le Havre in France where an ongoing study into Positive Pressure Tactical Ventilation (PPV) is being carried out. The visits to the facility, organised by LEADER GROUP UK LTD, enable fire officers to observe how the work at the University is laying the foundation for the introduction of a European standard covering PPV equipment as well as developing new theories on the implementation strategy related to the operational use of PPV.

When I first introduced the concepts of 'tactical ventilation' using Positive Pressure fans to the UK fire service back in the 1980s the idea was considered highly controversial. My articles through the pages of this very Journal prompted some interesting debate that led to one 'learned person' suggesting I should invent a 'bazooka style gun' that firefighters could use to blast holes in burning buildings to relieve smoke conditions!  However, the transition in thinking over the past 15 years is demonstrated by current advice given to firefighters, expanded from an original advisory paragraph of 63 words in the manual of firemanship to a more recent 71 page manual devoted entirely to 'tactical ventilation', PPV and compartment firefighting. In the early days I was supported by CFO John Craig and the brigades in Wiltshire, Bedfordshire, Grampian and Essex who helped develop a greater awareness in the potential of PPV and without CFO Bull's impetus through Tyne & Wear's involvement in the mid 1990s we may never have reached the stage we are at now.

It is currently estimated^[1] that 42 percent of UK fire brigades have purchased PPV equipment and that this figure is set to double to over 84 percent by the end of 2000! Of the brigades currently using PPV,  27 percent are promoting it as a 'fire attack' tool whereas a further 43 percent are using PPV in post fire situations only. The remaining 30 percent are in the process of training their firefighters and are currently evaluating the implementation strategy advised in DCOL 14/99.

In December 1999 we were pleased at Leader Group UK Ltd to sponsor an opportunity for 46 UK Fire Officers representing 27 brigades to visit the scientific research facility based at the University of Le Havre in France where an ongoing two year research project into the practical use of PPV equipment is being undertaken. This is probably the most detailed research project into Positive Pressure Ventilation outside of the USA and scientists at the University are laying the foundation towards the creation of a new european standard for PPV equipment in the new millenium. Under the guidance of Professor Michel Lebay the fire officers were taken through a range of airflow experiments in the purpose built facility where different fans of varying size, style and manufacture were placed in various positions in relation to the inlet doorway. The benefits of PPV were demonstrated by utilising blowers in singular, back to back and 'V' formations and airflows through the compartment were strictly monitored and displayed on computer screens for all to see.

Seal around the door.   

The operating principles of both 'turbo' style and 'conventional' fans were considered and the traditional 'seal around the door' concept so often associated with 'conventional' air streams (figure one) was shown to not to exist by use of a bubble machine. It was clear to see that a negative or neutral pressure still exists around the periphery of the inlet doorway where bubbles were moving both in and out of the inlet point whilst the fans were working at full capacity. Says Mr Lebay, 'there actually is no true 'air seal' at the doorway' and air flows at the entry point behave similarly with both turbo and conventional styles of fan. However, it was clear from the demonstrations that turbo units create a far higher airflow through a structure than conventional units on a size for size basis. This is because of the air entrainment effects at the entry point which are specific to the 'turbo' style of ventilator (figure two) and the fact that overlapping air-cones from ''conventional' units demonstrate much air wastage as up to 30 percent of the airflow fails to enter the structure.

This fallacy of an 'air seal' at the entry point was also noted in earlier tests by the UK scientific Fire Research & Development Group (FRDG) where it was noted that 'no significant differences were observed between turbo ventilators and conventional PPV fans.....both appeared to produce similar air streams at the entry point and both seemed to clear compartmental smoke conditions in roughly the same time'. The FRDG had used 'streamers' at the entry point instead of bubbles but had reached a similar conclusion as to the existence of a true 'air seal'.

  The recent Dear Chief Officers Letter (14/1999) advising an implementation strategy for the operational use of Positive Pressure Ventilation mentioned the 'seal around the door' concept and inadvertently mislead some brigades into believing that such a seal was necessary to implement the strategy with 'best effect'. The Home Office (Fire Policy Unit) has since redefined its views in a letter to Leader Group UK Ltd and assured that 'the guidance in the DCOL does not purport!to make a judgement about the relative merits of different types (styles) of fan' and confirms 'no significant differences' should be drawn between the turbo and conventional styles of fan 'which appear to seal the (inlet) door (way) to the same extent'.

  Information Exchange

  The visits to the scientific research facility were preceded by seminars where Commandant Michel Perosglio discussed the French Fire Service's ten years of experience with PPV or PPA (Positive Pressure Attack).  A series of lively debates between the UK contingent and the French fire officer resulted in some excellent information exchange.

  Additional workshops were hosted by Groupe Leader at their offices in Le Havre where design technology was openly discussed with chief design engineer Pascal Manche and the needs of the user were addressed. Although the research facility is openly funded as a european third party (unbiased) test house we were happy for UK fire officers to see our equipment demonstrated against other manufacturers fans. "Our confidence is measured by the performance of our PPV fans that repeatedly out-perform all competitor's models in the test facility", said Groupe Leader's Managing Director Thierry DELERUE. The delegates were suitably impressed by both 'conventional' and 'turbo' style fans in Groupe Leader's wide range which clearly demonstrated superior air flows in comparison to the larger American models in the scientific setting of the test house^[2] - "These units have been designed and tested with the firefighter in mind and have proven to be robust and durable enough to withstand the rigours of everyday use" said Mr DeLerue. "They are currently operational with several brigades throughout the UK and we are constantly receiving requests to supply them with additional fans". The conventional units have been the most popular to date although there is a growing trend towards the smaller turbo style fan that fits into reduced locker space and eases stowage problems. "We have been approached by several brigades to supply them with a package comprising of a small lightweight portable pump and a PPV (turbo) blower that combine to readily fit into the locker that previously housed a larger portable pump", he went on to say.

  Its easy for manufacturers to make 'claims' in their literature concerning the volume of air any particular fan can 'push'. However, this was an ideal opportunity for fire officers to witness the effectiveness of Groupe Leader fans alongside all the major competitors and decide for themselves exactly who has  'air superiority'.

AMCA Standards or European?

The standards for PPV fans have been regulated to date by the Air Movement & Control Association (AMCA) in the USA who admit themselves that their programme of tests are not designed to measure the effectiveness of PPV airflows or an individual unit's ability to move smoke through and out of a compartment or structure. The development of specific standards suited to such tasks are being addressed by the University of Le Havre project and hopefully a european model will evolve sometime in the not too distant future.

Groupe Leader are manufacturers of a wide range of both 'turbo' and 'conventional' style PPV blowers. For a demonstration contact Leader Group UK Ltd - Telephone: 0151 334 0202 - E-Mail: LdrGroupUK@aol.com - Internet http://www.groupe-leader.fr