Ventilation of Enclosed and Underground Car Parks

PSB have commisioned a short presentation film about the Impulse System. This can be ordered on DVD from our head office. A small web movie version is also available by following the link below.

Watch the DVD preview HERE

The System in Detail

The PSB Impulse Ventilation System consists of main exhaust fans to provide the airflow rate through the car park, unique impulse fans to control the airflow direction, a CO & smoke detection system and a main control panel. The CO & smoke detectors provide a signal to the main control panel indicating the environmental conditions within the car park. This enables selective operation of impulse fans in individual areas affected by CO pollution, or in the event of a fire, the strategic operation of individually selected impulse fans. The selective operation of impulse fans is designed to contain smoke within a defined & pre-determined corridor and control its flow to the extract point. Should a fire situation arise, PSB can guarantee the smoke path and remain the only company to make this claim.

An Advanced Ductless System

The Impulse Ventilation System does not use ducting; consequently, the level of pressure drop is much lower than that of the traditional type of system. The reduced pressure drop means that the extract fans are required to operate at much lower pressures, meaning smaller generators and lower running costs due to lower kilowatts taken by the fans. It has been shown that savings of well in excess of 40% in running costs can be realised, hence a real incentive for a car parks owner to install this type of system. Another plus to the system is its appearance. Instead of a bulky ducting system running through the length of the car park roof, the system uses a series of sleek impulse fans to provide the air movement. These can be manufactured in any colour so as to fit in with the car park colour scheme.

Ventilating for Vehicle Emissions

The normal means of ventilating a basement car park is to apply the fairly arbitrary 6 air changes per hour as required under Building Regulations. This rule applies whatever the car park size, level of occupancy, traffic movement or time of day. This is nice and simple and it complies with building regulations, but, in these days of depleting ozone layers and the need to limit atmospheric pollution, it is time to apply a more engineered approach to the ventilation of car parks.

By the use of CO detectors linked through the unique PSB-designed PLC software, the impulse ventilation system is able to control the level of ventilation within the car park to ensure that contamination levels are kept well within the specified criteria. Varying the rate of ventilation means that the system need only operate at full load for probably 10-15% of the time, adding to the significant savings in operating costs.

Controlling Smoke in an Emergency

The system employs a "high-density" distribution of PSB multi-criteria smoke detectors to ensure comprehensive coverage of the car park. The purpose in having multi-criteria detection is two-fold; firstly it permits an early alarm of a developing fire and second, it minimises the risk of false alarms, which is beneficial to the car parks owner, users and fire service. The high-density matrix of the detectors also enables the system to identify the precise location of a fire and subsequent control of the smoke. On detection of smoke, the extract rate of the system is increased and the impulse fans within the fire zone are activated, creating a virtual corridor of smoke.

Safety for the Public and Efficiency for Firefighters

Apart from the protection of the public and their escape routes, a further and equally important aspect of the system is to safeguard fire fighters in their approach to and tackling of the fire. By controlling the flow of smoke, three sides of the vehicle are kept clear of smoke so that visibility is maximised. The velocity of air over the fire, whilst not too great so as to cause an added fire risk, is sufficient to cool the gases to a level, which permits a relatively safe approach and reduces further collateral damage.

 

Engineered Ventilation

Nowadays, vehicle fire loads vary significantly. In some cases such as people carriers, can be up to 8mW per vehicle. The Impulse Ventilation System, due to its engineered approach and level of flexibility is far more easily able to cope with such variations than the old ducted system. Larger fire loads mean higher extract rates. With a ducted system, much larger ducting will be necessary to cater for the higher volumes. The alternative is even higher-pressure drops with the consequential spiralling level of installed motor power.

 

Testing and Product Rating

"The Key to reliability is product integrity"


A Real Fire Test at Villa Arena, Amsterdam.

All products used by the PSB Impulse Ventilation System have been thoroughly tested and approved. Along with cold smoke tests, a number of fire tests have been undertaken, the last being at the Villa Arena Car Park in Amsterdam (Europe's largest single storey underground car park.) The test was overseen by the Amsterdam Fire Brigade and initially involved lighting one car, parked between 2 other cars. Because of the high-density of the multi-criteria detectors, the system detected the fire and was activated automatically on to fire ventilation mode within 3 minutes.

The fire had been artificially accelerated by the fire service who opened one of the car windows to increase the fire load. As the PSB system forced so much air over the car, the fire began to die at which point the test was stopped and restarted after adding combustibles to the car. Over the following 15 minutes, the fire grew and eventually spread to the adjacent cars. Throughout this, the fire service was able to stand just metres away from the fire, demonstrating the cooling effect of the system over the fire.

Additionally as the smoke was being controlled away from the fire, the fire service was able to closely monitor its progress and eventually extinguish the fire with ease. The system worked as planned and proved itself without the use of a sprinkler system, as is commonplace with many other installations where a PSB System is installed.