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This publication is a guide only. Reference to local codes and standards for compliance of system design should always be sought. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, for any purpose without the express written permission of Vision Systems. Warehouses, distribution centres and superstore facilities are environments that contain a diverse scope of inventory that range from raw manufacturing materials and wholesale goods, through to retail consumables and finished products.
The loss of inventory or equipment is only a small part of the overall loss incurred as a result of a fire or thermal event. It is essential that reliable, very early smoke detection systems be deployed to protect the facility and stock from the threat of fire. As an innovative pioneer of aspirating technology, VESDA provides the earliest possible warning of a potential fire by detecting the incipient pre-combustion stage of a fire event.
A team of VESDA engineers who have extensive design and installation knowledge in warehouse environments have assisted in the development of this Design Guide. The content herein is to be used as a reference by designers and consultants when specifying a VESDA system.
It discusses the relevant design considerations, and recommends the installation of an aspirating smoke detection system in warehouse facilities. NOTE: The Design Guide has been produced as a global reference and should be used in conjunction with region specific fire codes and national standards. The following aspects should be considered during the specification and design of an aspirating system:. The diversity in the layout configuration, fire risk, operational hours and variety of stored goods are primary factors when determining the appropriate detection system for a warehouse facility.
In comparison, high-density stores that house fast moving consumer goods such as. The highly combustible nature of polystyrene and polyurethane foams, wooden pallets, cardboard boxes and plastic wrapping also increase the risk factor. Although suppression i. While such systems will provide containment, the risk of water and smoke damage to business-critical stock is increased.
A fire must be detected at the earliest stage to reduce the risk of facility and stock loss. The simple maintenance requirements and the ease of servicing the VESDA system significantly reduce the long term costs i.
The following guidelines are to assist consultants and designers achieve the optimum level of detection required within warehouse storage applications. International standards and codes of practice should always be taken into consideration.
The spacing or density of the sampling holes detection points is dictated by local standards. The flexibility of pipework location allows detection to be placed where it is required, as well as complying to the code requirement. Alarm levels and appropriate levels of response are determined by each individual application environment and are not addressed in the Design Guide.
The following sections describe design recommendations related to the different detection areas. This program illustrates the significance of various parameters in an aspirating smoke detection system so that the most appropriate design can be applied. The choice and level of protection is dependent on the identified risks and requirements of the local fire codes and standards, the insurance company and the client.
VESDA provides the functionality to address the individual configuration criteria, while maintaining adherence to the grid-based codes and standards layout. Sampling pipes for aspirated smoke detection systems are typically located at the roof level and within the racking system. Pipe work layout and sampling point location should be installed as per the standards for point detection.
In facilities where the layout prevents this code adherence e. Smoke stratification: It is essential to consider the possibility of stratification. It is advisable to conduct smoke tests using a smoke pellet or other approved method.
VESDA sampling pipes can be located down the walls or within the racking to overcome stratification problems. See Section 3. Height restrictions: Local codes indicate limitations and height coverage specifications.
Rack layout: The layout configuration of the storage racks may not allow for convenient positioning of sampling points in compliance with the relevant code i. It is often necessary to provide a greater density of sampling points in order to match the rack configuration.
Maintenance: The on-going maintenance requirements for a detection system is a major consideration. Various sampling methods can be used in warehouse facilities. The selection of sampling configuration is dependant upon the application and internal requirements of the warehouse facility i.
The method of locating sampling holes is identical for pipe work sampling, drop pipes or capillary sampling; sampling holes in aspirating smoke detection systems are typically positioned where conventional detectors would normally be placed. Global codes and standards recommend an area of coverage per detector; usually determined by a using a grid layout.
Most standards define different area coverage dependent on certain criteria and reference should be made to your relevant standard. Refer to Figure 1. For example, if high-bay racking is present, detectors and sampling points should be considered in addition to the codes and standards grid layout specification. This provides full protection of the racking and the actual warehouse facility. System design should be the responsibility of an accredited VESDA distributor or agent to ensure the correct application design is maintained.
External climatic changes can cause expansion and contraction of the pipework. It is recommended conduit saddles be used to allow for small amounts of movement. The expansion and contraction caused by temperature variation may also necessitate the installation of airtight expansion joints in the pipe work. The placement of expansion joints allows the pipe to contract and expand without exerting pressure on the pipe fixtures.
To ensure ease of mounting and maintenance, the detector is typically mounted at working height. Refer to Figure 2. Performance-based design determines the best fire protection system by assessing the environmental risks at the concept design stage. Traditional prescriptive codes and standards have proven to provide an appropriate level of fire protection with a reasonable safety margin.
However, as tools and industry expertise continues to develop, the fire protection strategy in many installations is being designed from a risk and performance-based design approach. This may include the use of computerised modeling tools i. Computational Fluid Dynamics and analysis of on-site tests i.
VESDA systems complement performance-based designs by detecting a fire event earlier than conventional detection systems.
VESDA is also easily incorporated into the overall Fire Response Plan, and verification tests can be administered to confirm that the installed system is providing the specified protection. The following sections address physical conditions and risks that occur in warehouses, relevant to a performance-based design approach to fire protection. NOTE: The arrangement of stock may alter the air dynamics airflow and air direction of the facility. It is recommended that performance tests i.
Smoke stratification occurs in many warehouse and factory environments and refers to the incidence of smoke layering, which is a result of heating and cooling of the air within the facility. If a small, incipient fire were to occur within a lower level of the racking, smoke would rise and form a layer below the hot air layer located at the roof level. To assist in sampling or detecting smoke within the stratification layer, it is recommended to sample at differing levels within the warehouse.
This allows air to be drawn from multiple heights or layers and therefore provides earlier detection. Several multiple level sampling methods are discussed below. Drop pipes detect the presence of incipient smoke by penetrating the hot air layer at the roof level. To provide complete detection of the warehouse area, it is recommended that both drop pipe and roof mounted sample points are installed. This allows for optimal sampling when the air at the roof level is either hot or cold.
Drop pipes can be up to a maximum of 8 metres 26ft long, however, local codes and standards should be consulted to determine the correct length for individual facility configurations.
The detector is generally mounted at the end of the racking at working height, and pipework is located horizontally through the racking at different levels. Refer to Figure 3. This allows for sampling at different heights through the racks and provides very early detection and minimises the downtime that would be experienced in the event of fire. The pipework is normally installed between back to back racks allowing for mechanical protection i. When installing above-rack drop pipe sampling, it is essential to ensure that the sample pipework is not at risk of damage by the operation of forklift trucks.
The drop pipes can be fitted to the sheltered side of the box section of the racking. If this is not possible, the pipework can be installed parallel with the rack frame. Drop pipes normally have two to three 2 to 3 holes drilled along their length, allowing sampling at different heights throughout the racking system. Refer to Figure 4. As the smoke spreads and diffuses throughout the warehouse, it becomes diluted and increasingly difficult to detect by conventional detection.
VESDA is the only detector able to cope with smoke dilution without compromising early detection. Cumulative detection refers to the ability to draw air from many points within the protected area into a single detector.
System maintenance requiring access and service of a conventional detection system to code requirement is a major cost factor in warehouse facilities. VESDA reduces the long term costs of maintenance and servicing as normal maintenance does not require access to the pipework, therefore there are no logistic issues or requirements such as disruption to operations i.
A simple method has been devised to allow cleaning of the sampling holes from ground level. The VESDA system detector is normally mounted at an easily accessible height and position within the facility. This allows for easy maintenance and servicing. This eliminates the need to check the sampling points and pipework that is mounted in inaccessible areas. Some warehouses such as superstores have ancillary areas such as public access zones and office space etc.
While fire codes and standards may not require the protection of ceiling voids in premises such as warehouses, there is very little cost impact of installing VESDA to protect this area. Capillary sampling is a complementary sampling method to pipe work sampling. The sampling pipe is located in the ceiling space, a capillary sampling tube connected from the pipe through the ceiling tile, and air is directly sampled from the protected area.
Refer to Figure 5. Location of the capillary sampling points should coincide with the grid layout as described in Figure 1- Grid Layout for Sampling Hole Locations. Warehouse plant rooms such as the air handling plant, forklift battery charge bay and workshop facilities exist as areas that normally contain high power appliances, volatile fuels and other combustible equipment and materials.
It is recommended that either capillary sampling or ceiling mounted pipework be installed to facilitate early detection in these areas.
This publication is a guide only. Reference to local codes and standards for compliance of system design should always be sought. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, for any purpose without the express written permission of Vision Systems. Warehouses, distribution centres and superstore facilities are environments that contain a diverse scope of inventory that range from raw manufacturing materials and wholesale goods, through to retail consumables and finished products. The loss of inventory or equipment is only a small part of the overall loss incurred as a result of a fire or thermal event. It is essential that reliable, very early smoke detection systems be deployed to protect the facility and stock from the threat of fire.
Vesda Pipe Network Design Guide 10193