Car Park Applications

The AST Impulse System in Detail
The AST Impulse Ventilation System consists of main exhaust fans to provide the airflow rate through the car park, impulse fans to control the airflow direction, a CO and smoke detection system and a main control panel.  The CO and 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 within 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 clearly defined and pre-determined corridor and control its flow to the extract point.

An Advanced Ductless System
The Impulse Ventilation System does not use ducting; consequently, therefore 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 operate at much lower pressures, meaning smaller generators or power supplies and lower running costs due to lower power usage by the fans.  It has been shown that savings in excess of 40% in running costs can be realised, hence a real incentive for a car parks owner to install the impulse type of system.  Another advantage to the system is the appearance.  Instead of a bulky ducting system running through the length of the car park roof, the system uses a series of aesthetic impulse fans to provide air movement.  These can be manufactured in any standard RAL colour to blend in with the car park colour scheme.

Ventilating for Vehicle Emissions
The standard method of ventilating a basement car park is to apply the arbitrary six air changes per hour as required under Building Regulations.  This rule applies whatever the car park size, its level of occupancy, traffic movement, or time of day.  To limit the car parks atmospheric pollution, the use of CO detectors linked through the AST control panel, is able to control the impulse ventilation system to regulate 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 only operates at full load at peak times of the day, adding to the significant savings in operating costs.

Controlling Smoke in an Emergency
The system employs a "high-density" distribution of AST multi-criteria smoke detectors that ensure comprehensive coverage of the car park.  The purpose in having multi-criteria detection has two purposes; firstly, it provides an early alarm of a developing fire and second, minimising 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 allows the system to identify the precise location of a fire and therefore subsequent control of the smoke.  Upon detection of smoke, the extract rate of the system is increased to maximum and the impulse fans within the fire zone are activated, creating a corridor of smoke to the main extract point.

Safety for the Public and Efficiency for Fire-fighters
As well as protection of the public and their escape routes, a further and equally important aspect of the system is the safety of the fire fighters in their approach both to and tackling of the fire.  By controlling the flow of smoke, upto three sides of the vehicle can be kept clear of smoke so that visibility is maximised.  The velocity of air over the fire is sufficient to cool the products of combustion to a level that permits a relatively safe approach and reduces further collateral damage.

Engineered Ventilation
Vehicle fire loads can vary significantly, and in some cases such as MPVs, can be up to 8Mw per vehicle.  The Impulse Ventilation System, due to its engineered approach and level of flexibility is able to cope with such variations better than the old ducted system.  As larger fire loads mean higher extract rates, a ducted system would require larger ducting to cater for the higher volumes or higher-pressure drops within the ducting that gives rise to installed motor power.