psb guide 6a - wittfan.de · the essential psb good practice guide 1 contents 3 system design 3.1...

The Essential PSB Good Practice Guide

Car Park Ventilation

1The Essential PSB Good Practice Guide

Contents

3 System Design3.1 Current Regulations on Car

Park Ventilation3.2 Design Considerations3.3 Extract Systems3.4 Fresh Air Make Up3.5 Design Fire Load3.6 Means of Escape3.7 Fire Fighting3.8 Airflow Rate3.9 Control of Smoke3.10 Activation of Impulse Fans

4 Sprinklers

5 The Option of Impulse Fans &Induction Fans5.1 Performance of a Jet Fan5.2 Relative Benefits of the Two

Types

Introduction

1 What is Impulse Ventilation?

2 Components of the ImpulseSystems2.1 Component Function2.2 Main Extract Fans2.3 Impulse Fans2.4 CO Monitoring2.5 Multi-criteria Smoke &

Heat Detectors

2.6 Extract Dampers2.7 Main Control Panel

2 The Essential PSB Good Practice Guide

6 Computerised Fluid DynamicsModelling

7 A Proven Track Record

8 Car Stacker Systems8.1 Fire Risk8.2 Risk of Gas Build up

Frequently asked questions

Introduction

3

Impulse ventilation is designed to achieve two principle objectives:

• Remove the need for space and energy consuming ducting and

• provide smoke control in the event of fire

Impulse ventilation is still treated as very new technology within the UnitedKingdom even though it has been extensively used throughout mainland Europefor over 15 years.

Since PSB introduced the Impulse Ventilation System into the UK in 2001 it has beenmet with much interest resulting in many questions about this unique andinnovative technology. The Good Practice Guide aims to answer these questionsand to provide a background to Impulse Ventilation and its efficient and effectiveapplication. It will also highlight the key design criteria and point out some of themajor pitfalls of poor design practice.


An Impulse Ventilation System is intended to provide effective ventilation ofenclosed and basement car parks without using ducting. This system is also suitablefor use in loading bays and service roads, although slightly different design criteriamay be required.(See figure 1)

Impulse ventilation differs from the conventional ventilation system in threeprinciple ways:

• Impulse fans replace ducting and provide control of the airflowwithin the car park.

• Smoke management and control are key features of the impulsesystem, a technique not usually possible with a ducted system.

• In larger car parks, the system engineering is based on a design firesize rather than the simple air exchange rates that are referred to inthe current building regulations.

1. What is Impulse Ventilation?



Figure 1

Ventilation Techniques

7

The components of a PSB Impulse Ventilation System include:

• Main extract fans• Impulse fans• Extract shaft or riser• CO detection system• Fully addressable multi-criteria smoke/heat detection system• Extract dampers & actuators• Main control panel• Fire service override switch• Option of remote monitoring/indication

Figure 2


2 Components of the Impulse System

System Components

8

The basic principle of the system is that the main extract fans provide the airchange rate within the car park whilst the impulse fans control the air flow direction.

The environmental conditions are constantly monitored by the use of CO andsmoke detection systems. This environmental data is then fed into the main controlpanel which will adjust the rate of ventilation accordingly.

A minimum of two main variable speed, parallel mounted exhaust fans are usedfor effective air flow control. These extract fans are rated at 50% of the maximumairflow rate.

The main extract fans must be suitably rated for operation within a smoke extractenvironment and it is therefore vitally important to ensure that they have beentested in accordance with the latest European standard EN I 2 I 0 I -3 to verify theirsuitability. Current building regulations specify that they must be suitable forwithstanding a temperature of 300°C for a period of not less than one hour.

2.1 ComponentFunction

2.2 MainExtract Fans

Figure 3

A Main Extract Fan



An impulse fan is designed to create the movement of a large volume of air viathe development of thrust. This is achieved by the creation of a concentrated highvelocity jet stream, which induces air movement and is based on a physical lawfirst established by Bernouilli.

The impulse fans are used to control the direction of the airflow within the car park,ensuring there are no stagnant areas under day to day ventilation conditions. In theevent of a fire, selective operation of the fans makes it possible to control the flowof smoke, achieved by use of the air entrainment characteristic of the impulse fan.

The impulse fans are two speed units operating at I400 and 2800rpm. The lowerspeed (I400rpm) enables airflow to be directed to all parts of the car park andcreate turbulence which facilitates the mixing and dilution of the contaminantgases with fresh air. The higher speed of 2900rpm is used only under fire conditions.

The impulse fans must also be rated to withstand the high temperatures associatedwith smoke extract fans, indeed, they are more likely to experience the highertemperatures than the main extract fans.

Therefore, it is vitally important to ensure that they have also been tested inaccordance with the latest European standard EN I 2 I 0 I -3 to confirm theirsuitability. Again, current building regulations specify that they must be suitable forwithstanding a temperature of 300°C for a period of not less than one hour.

2.3 Impulse Fans

Definition of anImpulse Fan

Figure 4

An Impulse Fan

Figure 5

10

Current building regulations require an airflow rate of 6 air changes per hour(Approved Document F). The arbitrary application of this requirement can result inconsiderable waste of energy, and resultant increase in operating costs. For 80% ofthe time, most car parks have little traffic movement, consequently very little vehicularexhaust pollution is present during that time, therefore a lower rate of ventilation canbe employed without compromising the optimal environmental conditions.

A variation in airflow rate is permitted within the relevant Approved Document,providing the level of pollution within the space is monitored and controlled withinthe specified limits. By varying the rate of ventilation according to trafficmovement, the Impulse Ventilation System requires lower rates of ventilationoverall, resulting in reduced operational costs. The usual ventilation rate is between3 and 6 air changes per hour dependent on the level of traffic movement and theconsequential level of exhaust emissions.

2.4 CO Monitoring


CO & LPG Monitor


Figure 6

Multi-criteria fire detector heads are used for two reasons:

• To reduce the chance of false alarm.• To provide for early detection of a developing fire.

The location and distribution of the fire detectors and their programming isextremely important to ensure the correct mode of operation of the system. This isparticularly the case in ramp or void areas.

The most commonly used type of detector incorporates both thermal and smokedetection within one head (see figure 6). Whilst multi-criteria heads will sense bothsmoke and vapours emitted from the early stages of a developing fire,conventional fire detection systems will only operate in the detection of heatdelaying detection

This feature is extremely important as a car fire is often confined to the passengercompartment of a vehicle, and consequently sufficient heat will not be releasedfrom the fire at detector level for some considerable time from initial ignition. This istime that is lost for the evacuation of the building and for alerting the fire service.

2.5 Multi-CriteriaSmoke & HeatDetectors

The Multi criteriaSmoke Detector

12

Under normal circumstances in multi-level car parks the extract dampers remainopen to provide the required ventilation on each level. In the event of fire, thedampers on the fire floor will remain open, but those on the non-fire floors will closeautomatically. This method of operation means that all the air extracted is drawnthough the fire floor and no smoke contamination will occur on the non-fire floors(see figure I 2).

2.6 Extract Dampers



Figure 7

The main control panel is the heart of the Impulse Ventilation System whichincludes a PLC (programmed for effective system operation) and all theswitchgear necessary to control the system operation. The main control panelcontinually receives signals from the CO and smoke detection monitors enablingthe system to respond to the conditions prevailing within the car park and providethe appropriate rate of ventilation and airflow direction.

Obviously, fires within car parks can involve more than one vehicle therefore it isimportant to consider the impact of a multi-vehicle fire at the same location on theperformance of the ventilation system.

Figure 7 shows a fire test, undertaken by PSB, involving three vehicles. It can beseen from the illustration that, even though three cars are involved in the fire, aclear approach to the vehicles is maintained for the fire-fighters, who are thenable to tackle the fire efficiently and reduce further damage caused by the fire.

Due to the ability of the Impulse Ventilation System’s control system to manipulatethe activation of the impulse fans, much greater control can be achieved, therebyfocusing the bulk of the airflow through the fire zone.

2.7 Main ControlPanel

Fire Test at the Villa ArenaCar Park, Amsterdam


Current building regulations do not consider a car park ventilation system as asystem of life safety due to the usually sparsely populated nature of car parks andthe limited or precise fire risk associated with them.

However, the new breed of vehicles emerging as the norm for domestic motoring,including people carriers and 4 x 4s, carry a much greater fire load than thevehicles on which the regulations were originally based. The fire load for theselarger vehicles can be at least twice as high as the assessment on which thecurrent building regulations are based, up to five times as high in some instances,largely due to the increasing use of plastics in the construction of modern vehicles.

The materials used in the production of the car upholstery have long beenoutlawed for use in domestic and commercial furniture, further increasing the realfire potential.

There are six main considerations which should be taken into account in the designof an Impulse Ventilation System

• Points at which contaminated air can be extracted

• Fresh air intake facilities

• Design fire load

• Means of escape

• Fire fighting

• Car park geometry

3 System Design

3.1 CurrentRegulations on Car ParkVentilation

3.2 DesignConsiderations

16

One or more extract points will be situated at the most suitable and practicallocations, normally on the perimeter of the car park and, ideally, at the oppositeend to the fresh air intake. Each extract point will have at least two extract fansoperating in parallel. Extract shafts can be either builders’ work shafts or of steelconstruction. This ensures an even and efficient airflow through the car park.

3.3 Extract System


Consideration of the fire load is an important factor in the design of a realistic andreliable ventilation rate for a car park. There are a number of sources ofinformation available to the design engineer, and a variety of opinions within theindustry as to the level of fire load that should be adopted.

It is generally accepted that the peak fire output of a domestic saloon vehicle willbe in the order of 3MW. However, as explained earlier, some vehicles have a muchgreater output. It is reasonable to base the design on the spread of fire to twoadditional vehicles as well as the vehicle of origin.

3.5 Design Fire Load

A facility must be made for fresh air to be drawn into the car park. For single levelcar parks it is most frequently the ramps that are used as the route for fresh airintake. This also allows for efficient ventilation of the ramps, which are often subjectto the highest level of pollution due to standing traffic.

Alternative methods of drawing in fresh air may have to be considered for carparks greater than two levels. This may involve lightwells, voids in the outer walls orthe use of fresh air supply fans.

In larger car parks, where more than one extract point is used, it may not benecessary to use all the extract points in the event of a fire. In such cases the

unused extract points may be used for fresh air supply by reversing the fans therebygaining further improvement in smoke control.

3.4 Fresh AirMake Up


3.6 Means ofEscape

Figure 8

The results ofa fire inMaastricht.

It can also be assumed that the two additional vehicles involved in the fire willpeak in fire output simultaneously, albeit unlikely, whilst the original source of firedies down. This scenario would result in a fire size as follows: (2 x 3MW) + 2MW = 8MW.

The location of the escape and fire-fighter access routes must be taken intoaccount at the design stage. In the event of a fire smoke flow is managed, as faras is practical, in order to avoid contamination of escape routes and ensuringaccess to them is not compromised.


The illustration demonstrates how, in a real fire situation, the flow of smoke wascontrolled to avoid contamination of the means of escape and maintain clearair for the greater part of the car park.

This is one of the major differences between a ducted and an impulse system. Aducted system will extract the smoky gases through each of the extract grilles atboth high and low level as illustrated in figure 9. An impulse system, through theintelligence of the system, enables greater control of the smoke flow through theselective activation of impulse fans

Figure 9

A DuctedSmokeDispersalSystem.


A key function of any car park ventilation system is to facilitate rapid access bythe fire services to the building and fire. The impulse system is designed to ensurethat at least one side of the vehicle is kept clear of smoke, thereby aiding visibilityand the approach of the fire service personnel.The traditional means of providing ventilation employing a ducted or smokedispersal system induces smoke to all areas of the car park causing visibility to berestricted, thereby impeding escape and hampering the approach to the fire bythe fire service. By adopting an engineered approach to the system design,rather than applying an arbitrary I 0 air changes per hour, irrespective of car parksize, the impulse system is able to control the flow of smoke by the selectiveoperation of the impulse fans. This will improve both access to the means ofescape by members of the public, and approach to the fire by the fire service.

3.7 Fire Fighting

The main fans are designed to remove the necessary quantity of air according tothe level of pollution created by traffic movement within the car park. Undernormal ventilation conditions, the airflow rate will be in the order of three airchanges per hour, or “trickle” ventilation during “off peak” periods, when there islittle traffic movement. The system will vary the rate of ventilation, and control thenumber of impulse fans operating according to the level of pollution.

On detection of heat or smoke, the airflow to the fire floor will be increased. Thisis done by the main extract fans increasing in speed and selected impulse fanswithin the fire zone automatically switching to high speed (2900rpm). All the airextracted from the car park will pass through the fire zone, controlled by theselective operation of the impulse fans and the closure of the extract dampers tothe non-fire floors, (see figures 9 & I I).Closure of the dampers will ensure that the extract is concentrated to the firefloor and smoke will not migrate to the remaining, otherwise unaffected, floors.

3.8 Airflow Rate

20

3.9 Control of Smoke


Due to the selective operation of the impulse fans on the fire floor, smoke will becontained and channelled through an air corridor, created by the jetstream of theimpulse fans and guided towards the extract point. The air movement outside thesmoke corridor will be induced into the corridor, trapping the smoke.

The impulse fans that operate under fire conditions will depend on the zone inwhich the fire occurs. The information provided via the fire detection system, willdetermine which fans should operate to control the smoke flow.

Activation of all, or too many, impulse fans will result in excessive, uncontrolledmovement of air which, in turn, will cause an aerodynamic overloading of themain extract fans with resultant smoke logging of a large proportion of, or even allof the car park. The system is based on overlapping zones which permits veryaccurate control of the smoke. This principle is illustrated in figure I 0.

The air velocity within the corridor is designed to be sufficient to overcome thebuoyancy effect of a design fire load, normally 8MW. Due to all the air extractedfrom the car park being concentrated into the smoke corridor, there will also be asignificant cooling effect on the smoky gases, thereby limiting the hazard of firespread and further structural damage.

The width of the smoke corridor will depend on a number of factors,

including floor to soffit height, number and depth of beams, size of car park andcar park geometry.

On the basis of the known design smoke corridor width, the floor to soffit heightand the known velocity needed to control the flow of a specific fire load, the airvolume that needs to be extracted from the car park under fire conditions can becalculated (see figure I I ).


Figure 10

Impulse Fan Arrangement & Overlapping Zones


Figure 11

Controlling Smoke Flow


Figure 12

Isolation of the Non-fire Floor

24

3.10 Activation ofImpulse Fans


Failure to activate the impulse fans in a fire situation may well result in the fire beingunventilated, the results of which are well known. Due to the lack of air there willbe an increase in smoke generation and higher smoke temperatures with theconsequential increase in damage to structure and property. Whilst the preciselocation of the impulse fans is to some extent flexible, the selection and distributionof them is obviously crucial to the performance of the ventilation system.

There are a number of key criteria necessary to consider during the design processto ensure reliable operation of the system. These criteria include:

• Slab to soffit height• Fan thrust• Spacing of fans• Number of fans in operation• Main fan extract rate• Smoke travel distance• Soffit contour

The thrust of the impulse fan will induce air movement equivalent to up to eighttimes the amount of air passing through the impulse fan itself. Consequently,activation of too many fans will disrupt the operation of the system as explained inparagraph 3.9. Activation of too few fans will result in the system’s inability toadequately control the airflow.

Similarly, the contour of the soffit will influence the aerodynamic performance ofthe impulse fans, which will have to be taken into account when determining thespacing and number of fans to be installed and activated.


Impulse Ventilation Systems, when properly designed and installed, effectively remove theneed for sprinklers within a car park. Designed for smoke control, the system will channelall the air through the fire zone, providing significant cooling to the smoky gasesdischarged by the fire and limiting the risk for fire spread.

With the early detection of a fire via the multi-criteria smoke and heat detection systemand the resultant early alarm to occupants enabling prompt evacuation and the controlof smoke flow, the practical need for sprinklers no longer exists.

If (for whatever reason) sprinklers are still installed in the car park, there will be no impacton the efficiency of the impulse system.

4 Sprinklers


A more recent development in car park ventilation fan is the centrifugal typeinduction fan which now compliments the axial Impulse fans. Collectively, these fansare both commonly referred to as Jet Fans. As with impulse ventilation systemsgenerally, with the further option of fan types without a full understanding of theirapplication, there are many pitfalls with potentially significant consequences thatawait the system design engineer.

These two ranges of fans are basically designed to provide the same functions andthese are:

• Influence the direction of airflow within the car park to ensure that all areas areefficiently ventilated

• Induce air turbulence during daily ventilation to ensure efficient mixing anddilution of pollutant gases with fresh air

• Manage the flow of hot smoky gases in the event of fire

5. The Option of Impulse Fans & Induction Fans

5.1 Performanceof a Jet Fan

The performance of both the impulse and induction fans are measured in terms ofthrust, usually expressed in Newtons. The level of thrust will determine the amountof air that the fan is capable of moving, not only the air passing through the fan,but the amount of air “induced” into the jetstream created at the fan outlet.

5.1.1 System Affects


The quantity of air movement created by the jetstream can be up to 8 times thatpassing through an impulse fan developing 50N of thrust. This level of air movementwill depend on the useable thrust which will be affected by the resistance toairflow created by the obstructions within the car park, such as downstand beams,containment and ducting. The amount of resistance caused by the obstructions istaken into account in the design of the system and the selection of the number offans.

One further consideration that must be taken in account is the number of jet fansoperating. Obviously, the greater the number of jet fans that are operating, thegreater the volume of air that will be moved, therefore, care must be taken toensure that the main extract fans will be of sufficient capacity to extract thatvolume of air otherwise the car park, in effect, will become pressurised. In such asituation for example, in a fire situation, smoke could be forced into escape andfire fighter access routes. This is particularly important when considering the use ofthe larger 100N Centrifugal type of fan.

A further consideration when using the larger of the centrifugal fans is the impacton sprinklers if they are used. Due to the width of the discharge nozzle of the 100Ncentrifugal fans, typically 1200mm, the high velocity discharge, in the order of25m/s, will have an adverse affect on sprinkler patterns. In such cases, it is muchbetter to use a larger number of smaller fans since, with the large nozzle size,spread of the high velocity air will impact on sprinklers even if the fan is locatedcentrally between sprinkler heads; it must be remembered that the performanceof a jet fan is based on the air induced into the jetstream from the surrounding areaand the induced air will also impact on the sprinkler pattern.


5.2 RelativeBenefits of theTwo Types

Each of the two types of fan has its relative benefits which are summarised below.The axial fan is largely superior in terms of system performance and efficiency,whilst the centrifugal fan provides benefits in terms if space, although this is mainlyrestricted to the smaller of the two fans.

On the basis of the known design smoke corridor width, the floor to soffit heightand the known velocity needed to control the flow of a specific fire load, the airvolume that needs to be extracted from the car park under fire conditions can becalculated (see figure I I ).

5.2.2 The AxialImpulse Fan(The Vortax)

The axial fans tend to be more flexible and more efficient than the centrifugal typeof jet fan. This is borne out by the following:

• Lower power requirement, 1.1KW as opposed to 1.4KW for the 50N fans and2.2KW against 2.6KW for the 100N.

• Improved directional control for jetstream giving greater control of smoke in fireconditions

• Lower system losses with less jetstream contact with soffit

• Quieter in operation

5.2.3 CentrifugalJet Fan (The Pulsar


These fans tend to give greater benefits when height of car parks is restricted,particularly in the case of the smaller centrifugal fan.

• Saving in height of 180mm on the 50N fan and 120mm on the 100N.

• Compact assembly for the smaller 50N fan

The larger motor capacity necessary in the centrifugal fan is not great for individualfans, though of course this will be more significant for the overall system, but theloss of efficiency is caused by the compactness of the fans. Due to the restrictedspace, there is not a full scroll which normally forms part of the centrifugal fanconstruction and this creates much higher dynamic losses within the fan.

Further losses are created at the discharge due to the greater proportion of thedischarge air being in contact with the soffit caused by the coanda effect, andthis will also cause greater losses due to more significant contact with downstandbeams and other obstructions.

PSB Pulsar Induction fan

Figure 13


The correct application of CFD modelling can produce particularly usefulinformation to aid the design process or to demonstrate the systems effectiveness.

CFD is one of many tools used in the design engineers’ arsenal; however someinstallations have highlighted the need for caution in relying too greatly on the resultsof CFD models. CFD is no different from any other stand-alone software, in that theresults rely on the accuracy and the interpretation of the resultant information.Without a full understanding of the system design principles and application, thefinal results are totally meaningless and maybe potentially dangerous.

6 Computational Fluid Dynamic Modelling

31


Impulse ventilation has been proven, not only in test conditions, but also in real firesituations. This can be seen from the results, not only from the fire in Maastricht illustratedin figure 8, but also a further

example illustrated in figure I 3, where the escape routes were kept clear of smoke as wellas the vast majority of the remaining car park.

7 A Proven Track Record

Figure 14

Smoke control in the Museumplein Multi-level Car Park

Car stacker systems are becoming increasingly popular with developers in order that theycan gain maximum use of limited basement space. With the use of stacker systems thereare additional considerations that need to be taken into account when considering thecar park ventilation scheme.

The most important considerations are:

• The risk of increased fire spread

• The consequential increased potential fire size

• The risk of build up of hazardous gases and vapours in the pits often associated withstacker mechanisms

8.0 Car Stacker Systems


PSB PitPurge stacker pit ventilation system

Figure 15


The build up of gases within the pits associated with the stacker systems is a seriousrisk and steps should be taken to provide “local” ventilation. This can mostefficiently be done using a purge system. An extract system would not be asefficient and would necessitate the installation of flameproof fans when a purgesystem only requires a standard type of fan.

The purge system should be designed to provide continuous ventilation duringnormal operation and shut down in the event of fire to avoid the risk of spreadingthe fire.

8.2 Risk of GasBuild Up

The potential for fire spread is greatly increased when stacker systems are useddue to the vehicles being parked one above the other in a rack typearrangement. For this reason, it is

advisable to

• consider the use of sprinklers to impede the rate of fire growth

• reconsider the design fire size, particularly if sprinklers are not used

8.1 Fire Risk

37

Frequently Asked Questions


Q What criteria are there for system design?

A (I) Net area of the car park, (2) Floor to soffit dimension, (3) Means ofescape, (4) Where air can be supplied, (5) Where air can be extracted

Q Does the Impulse Ventilation System meet the requirement of 50% high & 50%low level ventilation ?

A Yes, the Impulse Ventilation System provides movement of air from floor tosoffit ensuring thorough ventilation of the entire car park.

Q Do the ramps need to be ventilated separately?

A There are specific requirements within the regulations for areas in which therecan be a particularly high build-up of gases. This may mean that the rampsneed to be separately ventilated but each application has to be consideredindividually

Q Is the cabling fire rated?

A Yes. Fire rated cable is used for fans and for detectors. In some cases, thecable can be located within the slab, which may remove the need for firerated cable to be used.

Q Is a standby electrical supply required?

A Yes. To meet the requirements of building regulations, a continuouselectrical supply must be maintained to the car park ventilation system.

Q Should the impulse fans be tested to withstand the same time/temperaturecriteria, set out in Building Regulations for main extract fans?


A Yes the fans must be tested to the European standard EN I 2 I 0 I - 3. PSB fansare in fact tested to withstand 300°C for 2 hours. This exceeds the currentBuilding Regulations requirements.

Q How does the Impulse Ventilation System compare to other (ducted) systems?

A Taking into account the saving on ducting costs and the cost of standbygenerators due to the significant reduction in power requirements, largesavings are likely in most cases. Additionally, in many cases, sprinkler systemsare not needed. An Impulse Ventilation System reacts extremely quickly,usually within about 2 minutes.

Q Do you get stagnant areas with the Impulse Ventilation System?

A No. Due to the strategic and calculated distribution of the impulse fans andthe monitoring of CO levels, there will be no stagnant areas within the carpark.

Q Does the PSB Impulse Ventilation System have higher operating costs?

A No. Due to the removal of ducting and it’s associated high pressure drop,significant reductions in power consumption are make with theconsequential reduction in related operating costs. Additionally, with COmonitoring there is no need for the system to work continually at fullcapacity.

Q Do you get false smoke alarms?

A False alarms are unlikely with the use of multi-criteria fire detectors.

Q What experience does PSB have in underground car park ventilation?


A PSB has installed over 400 systems into car parks of various sizes throughoutEurope, with vehicle capacities ranging from 17 up to 5000 cars at theAlmada Forum in Portugal.

Q Why must we use PSB specified products?

A PSB has researched and developed the system for a number of years. In thistime, PSB has established strong links with a number of suppliers. Thereliability, performance and quality of the products are of great importancein such a system and by using specified suppliers and products tested to thelatest European standards, we can ensure that this reliability is passed ontoour customers.

Q Can the system be tailored to meet specific requirements?

A PSB will consider any specific design requests and, if viable, include them inthe system. PSB can also colour code impulse fans to indicate different levelsor zones within the car park so that customers are able to find their vehiclemore quickly.

Q Concern is expressed that, if the system starts too quickly on detection of fire,people such as the elderly or infirm may be caught and trapped within a hotdense smoke corridor.

A Due to the use of multi-criteria smoke detection, the Impulse system detectsa fire at a very early stage, long before dense smoke is emitted,consequently, the situation should not arise. However, where this is aconcern, the system start maybe delayed and alarms activated, allowingan extended period for escape.are in fact tested to withstand 300°C for 2hours. This exceeds the current Building Regulations requirements.


Copyright © PSB-UK Limited 2007

All rights reserved

The contents of this document remain the property of PSB-UK Limited and must not be copied, stored ortransmitted without prior permission, in writing, from PSB-Uk Limited

PSB UK Ltd. Witt House, Brookwoods Industrial Estate, Burrwood Way, HolywellGreen, Halifax, HX4 9BH UK

Web: www.psbuk.comTel: +44 (0) 1422 378131

Fax: +44 (0) 1422 377321 Email: [email protected]

A member of the WITT & Sohn Group of Companies

Car Park Ventilation

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