Importance of Smoke Control Systems, Types and Use of Smoke Ventilation Systems - Report Example

PROJECT DESIGN Student’s Name Code + Course name Professor’s name University City, State Date Table of Contents Introduction 3 Importance of Smoke Control Systems 4 Types and Use of Smoke Ventilation Systems 4 Natural Smoke Ventilation Systems 5 Mechanical Smoke Ventilation Systems 10 Installation and Equipment 12 Acceptance Testing 13 References 13 Reviewing the use of natural and mechanical smoke ventilation systems in common corridors of apartment blocks Introduction In apartment blocks, controlling smoke in common escape routes is essential for the purpose of improving the conditions necessary for escaping as well as fire fighting. Smoke control is usually achieved by way of minimizing obstruction, toxicity as well as thermal exposure in routes that are commonly used in apartment blocks. It improves the conditions necessary for fire as well as rescue services (SE Controls 2015, p.1). For any apartment design to be approved and its process to be successful, the team making the design has the responsibility of ensuring its viability. They should consider good system design objectives, analysis of Computational Fluid Dynamics should be made with the scenarios well calculated. Agreement and documentation of the modeling, pass, and fail criteria should be done before the design commences. Specifically, the design team should take care of the different operating models for the means of escape as well as fire fighting operations. The designer of the smoke control systems should ensure that the proposed systems go together with the fire strategy of the building and provides the required levels of fire safety. Figure 1: Sample Smoke Ventilation Design Source: Advanced Smoke Group (2015, p.1) There are different types of smoke ventilation systems that can be used by apartment designers including, natural, mechanical and pressure systems. This report aims at discussing the use of natural and mechanical smoke ventilation systems in common corridors of apartment blocks. Importance of Smoke Control Systems Colt International Licensing Ltd (2015, p.1) argues that, smoke control systems in apartment buildings are used to protect the escape routes like common corridors to allow easy escape during the event of fire. The aim is to keep the corridors smoke free as well as improve the conditions in the corridors that open to the protected stairs. It is easy for smoke to spread from the apartment to the corridors when the door is left open hence making it difficult for occupants to escape (Department for Communities and Local Government 2007, p.29). The fire as well as rescue teams need a clear access to stairs in the apartment to allow them form bridgehead for their operations with the use of fire fighting shaft that is protected from smoke (The Smoke Ventilation Company UK 2015, p.1). Smoke control systems helps in preventing flashover as well as the succeeding full development of fire. They also reduce the thermal damage that may occur on the structural components at the time of fire. Apartment corridors are installed with smoke clearance ventilation systems to ventilate them being logged completely with smoke in the time of fire. The intention is to clear smoke at the corridors and facilitate access before the smoke becomes threatening to life. Types and Use of Smoke Ventilation Systems The use of smoke ventilation systems in apartment corridors depends on the building layout. This report analyzes two types of systems including natural ventilation systems and mechanical ventilation systems. When designing an apartment, the distance between fire doors within corridors should be 30m. The length of the dead end corridors should be 7.5m. This ensures that there is a short distance that people will travel through smoke. If the apartments are sprinklered, the length of the dead end corridors should be 15m. Smoke control systems should be provided for each corridor opening to every stair for stopping the spread of smoke to the stairs (Building Regulations 2000). Natural Smoke Ventilation Systems Natural ventilations can be installed using AOVs or shafts. Automatically opening ventilators (AOVs) can be used for the purpose of evacuating smoke where corridors extend to the external walls (Advanced Smoke Group 2015, p.1). The use of shafts in natural ventilation systems may also be used in evacuating smoke. For corridors that have external walls, OV’s and AOVA’s can be used. Considering that natural ventilation is the most simple as well as cost effective choice, it is the best ventilation type to be used in corridors that extend to external walls. In this case, the corridor AOV or OV used should be 1.5m2 at each level (Figure 2). AOVs are usually necessary when an access to a single stair is available. On the other hand, OVs are allowed access to multiple stairs is available. However, the AOV at the stair head require to automatically open every time when the OV is opened (Smoke Control Services Ltd 2015, p.9). Therefore, the use of an AOV should be a common practice in any case. There are different types of AOVs that can be used including; Coltlite louvred ventilators as well as Kameleon casement ventilators. Figure 2: Corridor with external walls Source: Colt International Limited (2015, p.5) For corridors that are enclosed, ventilation shafts can be used since there is no external wall that is adjacent to the corridor. Here, a single smoke shaft which is vertical should be installed all through the apartment to serve at each level together with a natural ventilator like the Colt Seefire ventilator on top of the shaft. From the corridor, the smoke usually enters the shaft in two ways, through the smoke damper like the Defender Smoke Damper. It can also enter the corridor through a fire rated door that is actuated like the Doorman. There are two types of shafts including; the natural like the standards smoke shaft and mechanical shaft like the Colt Mechanical Shaft. The natural or standard ventilation shaft requires a 1.0m2 of open ventilator within each corridor opening into a 1.5m2 shaft open at the top (Figure 3). The standard shaft can be in the form of a Defended damper or even a Doorman fire rated door that is actuated. This type of shaft is usually operated automatically. Figure 3: Standard Ventilation Shaft Source: Colt International Limited (2015, p.5) These types of shafts have various benefits. They do not require fans in their cabling as well as controls together with their standby power requirements. They produce low noise since they are virtually silent. Their cost is low in terms of purchasing and operations since they require small power as well as limited equipment for testing and maintaining. These shafts in ventilations do not require a roof top plant. Natural ventilation is usually the norm for installing in common apartment corridors. The recommended natural ventilations include; natural wall vents and natural vent shafts at the stair head. Natural ventilation usually works by way of harnessing forces from the wind as well as thermal buoyancy so as to drive the flow of air through the ventilator (Fire Design Solutions 2014, p.1). For the thermal application, the driving force that is anticipated is the hot smoke buoyancy that comes from the fire. However, these buoyancy forces are usually small when compared to forces from wind; there is a high possibility of the performance being affected by wind. Natural ventilation requires a source of air inlet as well as an opening of the exhaust for it to operate effectively (Figure 4). For a wall that is mounted with a vent, the vent serves to provide an air inlet at the bottom as well as an exhaust at the top. An inlet air can also be provided using the stair door after opening. This requires a vent at the stair head so as to assist in venting any smoke. Figure 4: Source of inlet air and Extract Point Source: Colt International Limited (2015, p.8) When designing natural smoke ventilation, it is necessary to consider freeing the open areas of the windows as well as the smoke shaft doors. They should be able to the escape of smoke when actuated. The doors, windows and ventilators should be able to be opened wide enough for the purpose of allowing smoke to enter the vent from the building (Building Regulations 2000). Provided that the designer has achieved a free area, one can make use of any type of vent. Normal choices include; louvered vent, bottom or side pivoting ventilator or window. The free area allows the selection and location of vents that are highly vulnerable to adverse effects of wind with the potential of blowing smoke back to the corridor. Therefore, apartment designers should take in consideration, the wind effects mitigation strategies when selecting as well as locating vents. Below is an example diagram of a free area. Figure 5: Free area of smoke ventilators When the designer uses a roof light as an opening vent that is automatic, an angle of 1400 should be provided as a minimum opening that will help in mitigating wind effects that are adverse. In case the designer used an outward opening at the bottom or a side hung corridor, the free area should be calculated by multiplying the vent length opposite the mechanism of the pivot by the opening distance of the ventilator whose measurement is 900 to the flap or window which is opened (Figure 6). Figure 6: Bottom or side hung corridor calculation Source (SE Controls 2015, p.3) a – distance the ventilator opens d – 900 to the opened window/flap For smoke shaft doors, the free area is calculated by the height of the door and the opening distance. The open ventilator free area that is measured should also be measured in the plane as shown in the above diagram. Here, the area is at minimum and there are right angles that direct the airflow. Mechanical Smoke Ventilation Systems Mechanical systems use shafts with dampers, fire doors, or powered ventilators can be used for evacuating smoke. Mechanical ventilations use mechanical shafts that serve to reduce the shaft cross section that is required. This reduced the additional costs that may be incurred through saving of space. For example, the Colt Mechanical Shaft usually uses a fan system that draws smoke out of the fire ventilation. It requires a shaft which is smaller at the size of 0.6m2. Mechanical ventilations are usually an alternative of the natural ventilations (Colt International Limited 2015, p.4). Mechanical Shafts have various benefits. They are small in size, flexible in layout and can provide more and improved ventilation for the compensation of extended travel distances. A mechanical shaft is usually better in performance than a natural shaft (SE Controls 2015, p.1). The reason is that a mechanical shaft extracts at a rate that is defined. It means that it s not affected by pressures from external winds. This type of shaft is less vulnerable to obstacles to the airflow in the duct. Mechanical ventilations are also known as powered ventilations. They have several requirements including; power maintenance, classified equipment for temperature, standby fans as well as wiring which is fire resistance (Lawrence Webster Forrest 2015, p.1). Consideration of internal pressures in the apartment is necessary and should be limited to ensure that the doors can be operated. Air inlet should be provided in the communal area for the prevention of system damage. It also ensures that there is no excessive pressurization or depressurization. This is to ensure that huge amounts of smoke are not drawn from the apartment as well as avoiding elevated pressure differentials to allow easy opening of escape doors. Designing of apartments should be done based on each floor level and how it can be affected by fire. What should open are the smoke vents on floor where the fire is coming from as well as other important vents. Mechanical system designers are required not to open ventilators in many floor levels and especially those that are connected through a smoke shaft. This helps in avoiding the spread of smoke to other unaffected areas in the apartment (Smoke Control Association 2012, p.24). The construction of smoke shafts should be made of materials that are non-combustible. All vents on the corridors must have a smoke or fire resistance performance of about E30S like that of fire door. After activating the system, all smoke vents at the top of the smoke shafts and bottom of the fire floor, and the vent at the stair head should be able to open. Also, the fans should be able to run with the speed of the design. Systems that can allow travel to extended corridor distances can also be designed. However, care should be taken when removing the subdivisions of the corridor. The travel distance through smoke should be limited to help in reducing the number of floor in the apartment to be evacuated by fire fighters. Installation and Equipment The equipment required should be selected to fit the particular performance requirements for the mechanical ventilation system. This is to ensure that the system works properly as expected. Designers should come up with an engineering plan which is detailed to help in guiding their installation as well as choice of equipment. Acceptance Testing After designing and installing the smoke ventilation system, it is important to test it to proof its performance alongside the design criteria. The installer should test it and an approving authority should witness the testing for approval of its compliance to the project specification as well as the approved design criteria. References Advanced Smoke Group, 2015, Residential Applications, Smoke Control, Available from The Building Regulations, 2000, Fire Safety, Approved Document B, Vol.2 – Buildings other than dwelling house. Colt International Licensing Ltd, 2015, Smoke control and environmental ventilation systems for multi-storey residential buildings, Smoke Control, Available from Colt International Limited, 2015, Smoke control and day to day ventilation systems for multi-storey residential buildings, Ventilation systems that help meet legislative requirements and achieve design objectives, Available from Fire Design Solutions, 2014, Natural Vs Mechanical Smoke Ventilation Systems, Standards, Available from Lawrence Webster Forrest, 2015, Mechanical Smoke Ventilation Systems (MSVS). Fire Engineering and Fire Risk Management Consultants, Available from SE Controls, 2015, Guidance on Smoke Control to Common Escape Routes in Apartment Buildings, Wellington, Available from Smoke Control Services Ltd, 2015, The Guide to Smoke Control Solutions for Flats, Smoke Control, Available from Smoke Control Association, 2012, Guidance on Smoke Control to Common Escape Routes in Apartment Buildings (Flats and Maisonettes), Available from The Smoke Ventilation Company UK, 2015, Smoke Control Solutions for Architects, Consultants and M & E Contractors, A basic Introduction to Smoke Control, Available from Read More