This year marks the 150th anniversary of the sprinkler. Since its invention, not only has the sprinkler evolved, but the world around it has not stood still either.
Text: Frank Bieber, VdS Schadenverhütung GmbH, Deputy Head of the Technical Inspection Department
Henry S. Parmelee did not have topics such as plastic production, automatic small divider racks or the electrical monitoring of the operational readiness of sprinkler systems on his radar when he received the patent for his “improvement of fireextinguishers” on August 11, 1874.
Since then, the regulations for the planning and installation of sprinkler systems have continued to develop in parallel with the technology. In 1910, the regulations for the installation of “fire extinguishing sprinkler systems” still consisted of a manageable ten pages (Figure 1). The regulations with the designations “Form 155” (1968; 20 pages), Form 3003 (1974; 81 pages) and VdS 2092 (1999; 142 pages) then gave rise to the CEA guidelines for sprinkler systems at European level and, building on these, to VdS CEA 4001 (2003; 227 pages).
VdS CEA 4001 has been continuously developed over the last 21 years and was published in January 2024 as the 8th edition with 286 pages. As with the last revisions, a three-year cycle has been maintained in which this standard work is updated.
A working group consisting of VdS experts, sprinkler system installers, insurers and experts has worked intensively on the further development of the regulations over 13 meeting days since the last edition. In addition, there are working groups that have developed amendments to specific topics.
The new version of VdS CEA 4001 is available in the VdS webshop, as are the updated versions of VdS 2108 (foam extinguishing systems) and VdS 2109 (water spray extinguishing systems). As with the previous edition, a synopsis is also available as an option for VdS CEA 4001, which - similar to the change mode of well-known word processing programs - shows the changes in detail. In principle, the application of the VdS guidelines is non-binding, but if application is agreed, the 2024 version must be applied at the latest for systems that are commissioned from 01.07.2024.
VdS 2108 “VdS guidelines for foam extinguishing systems, planning and installation” and VdS 2109 “VdS guidelines for water spray extinguishing systems, planning and installation” were also revised at the same time. The changes to these guidelines are essentially limited to the adoption of changes from VdS CEA 4001 (e.g. requirements for the water supply).
Some of the changes in VdS CEA 4001 : 2024-01 (08) are discussed below.
Extinguishing system vs. firefighting system
In common parlance and also in the relevant regulations (e.g. the Model Ordinance on Places of Assembly), the term (automatic) fire extinguishing systems is used. However, this was and is actually wrong. The aim of the sprinkler system has always been “to detect and extinguish a fire at the incipient stage or to bring the fire under control so that it can be extinguished by other means. The final extinguishing must be carried out by called-in forces (e.g. the fire department)."
The term “fire-fighting system” is therefore actually more appropriate, as the forces called in (usually the fire department) may still have to extinguish the fire. However, with an ever-increasing density in the logistics sector (keywords: AKL, TL-ASRS), the fire department is increasingly faced with major challenges in reaching the source of the fire (see also specialist lecture “Trends and challenges in distribution warehouses - Are sprinklers alone still sufficient?” by Matthias Heise & Stuart Lloyd, Zurich Insurance Company, at the VdS-BrandSchutzTage 2023).
For the aforementioned reasons, the following sentence is added to the objectives of the sprinkler system: “For high-bay racking systems in general and multi-row racking in particular, a concept must be drawn up as to how the source of the fire can be reached and finally extinguished in the event of a fire.”
Classification
With the publication of “CEA 4001 - Sprinkler Systems Planning and Installation ”1 at the beginning of this millennium, VdS CEA 4001 was developed in Germany to combine the new European regulations with the proven regulations of VdS 2092. To this end, supplementary texts and requirements were added to the text of CEA 4001. These were (mostly) highlighted in gray. Thus, there was Class 2, which represented the European level and offered a high level of protection for personal and material assets, and Class 1, which, with its additions, provided a very high level of protection.
1 Created by the Comité Européen des Assurances (CEA); today: Insurance Europe
In recent years and decades, this separation has become increasingly blurred. In Germany, sensible changes have also been made to the original CEA text. Technical developments and innovations were not highlighted in gray and should therefore apply to both classes. In the end, it was essentially the water supply that described the CEA requirements on the one hand (single water supply, single water supply with increased reliability, double water supply) and the old requirements from VdS 2092 (water supply 1st-4th type) on the other.
An essential feature of the class 1 system was often the compressed air water tank (DLWB), which was usually required from a water supply of the 3rd type. This highly reliable component stores water and energy and continues to function even in the event of a power or tank failure. In times of ever-increasing water pressures and ESFR sprinklers that eject 1,500 l/min (K480 @ 9 bar initial pressure), the effectiveness of this component is reduced. In the new edition, the water supply has been completely revised, and in this context the division into classes 1 and 2 has also been dropped. A uniform class is now described, which corresponds to the very high protection value of the former class 1. This means that it can also be used when regulations require a class 1 system.
In the few places outside the water supply where there were additional requirements for Class 1, these were examined on a case-by-case basis and generally adopted as general requirements.
Bei den wenigen Stellen außerhalb der Wasserversorgung, bei denen Zusatzanforderungen für die Klasse 1 bestanden, wurden diese im Einzelfall geprüft und in der Regel als allgemeine Anforderungen übernommen.
Water supply system
As a result of the dissolution of the classification system, the water supplies of the 1st-4th type are no longer applicable.CEA 4001 and DIN EN 12845 were used as a guide and the following definitions were established.
Simple water supply
According to section 8.6.1, a simple water supply must meet the requirements for pressure, flow rate and operating time specified in sections 6 and 8.
Permissible simple water supplies are listed below:
- (a) Public water supply network
- (b) Public water supply network with one or more booster pump(s)
- (c) Compressed air water tank (LH or OH1 systems only)
- (d) Elevated tanks
- (e) Container with one or more pump(s)
- (f) Natural and artificial water sources with one or more pumps
Essentially, we have the 2nd type of water supply with a tank and a pump.
Simple water supply with increased reliability
Simple water supplies with increased reliability are water supplies that are considered to be of higher quality due to their higher degree of reliability. These include
- (a) Public water supply network fed from two sides, each side being capable of meeting the pressure and flow requirements of the system alone; it must be fed from two or more water sources and must not be dependent on a single main supply pipe at any point. If a pumping system is required, two or more pumps must be provided.
- (b) Elevated tanks without booster pumps
- (c) Container with two or more pumps
- (d) Natural and artificial inexhaustible water sources with two or more pumps, where the necessary water rate is still available if one pump fails
- (e) Tank with one pump and one compressed air water tank (LH and OH only)
50% solutions
For both the single water supply with increased reliability and the dual water supply, it is not necessary to select pumps that can supply 100% of the required water rate. Taking into account the approach that the failure of one pump must not have any effect, three pumps with 50% of the required flow rate each can also be used.
In the case of a simple water supply with increased reliability, all three pumps can draw the water from a common tank (see Figure 5). The energy supplies for the pumps must also be selected in such a way that there is no impairment if one energy source fails. This is often realized in such a way that pump 1 has a mains supply, pump 2 has a supply from the backup power generator and pump 3 has a double switch cabinet with both supplies.
The use of the tanks is slightly different with the dual water supply. Here, the failure of one tank must not have any effect. This is not feasible with two 100% water tanks, so that three 50% tanks must also be used here (see Figure 6).
The directive also contains examples of the use of diesel pumps for both types of water supply.
Selecting the water supply
The exciting question now is when I can or must use which water supply. This question was based on the existing Class 1, but the draft of DIN EN 12845-1 was also taken into account. The result is a size- and risk-dependent matrix for selecting the water supply (see Table 1).
The reason why the operating times are sometimes lower than in other international regulations is the hydraulic calculation. The water requirement is still determined using the most favorable effective area and not the least favorable as in other regulations. Underground car parks, where it cannot be ruled out that electric cars will also be parked there, must have an operating time of 60 minutes and a fire department supply.
Pumps
Due to the elimination of the class division, some regulations have been simplified here. Previously, there were differences as to whether 5⁄6 or 2⁄3 of the water volume of a tank could be above the center of the pump. Now it is a standard 5⁄6 of the water content that must be above the center of the pump in order for it to be an inlet operation. New drawings have been included in the regulations for clarification (see Figure 7).
The dimensioning of the suction line has also been standardized. The flow velocity may now be a uniform maximum of 2.5 m/s and the negative pressure may reach a maximum of 0.4 bar. This supposed reduction in the requirements is possible because the determination of the NPSH value is now mandatory. This is the relevant value to ensure a reliable supply to the sprinkler pump.
Multi-deep shelving
Multiple depth racks or multiple row racks (MRR) are often used for the dense storage of materials. Chapter 11.5.5 previously only described solutions up to a rack width of 6.4 m. The chapter has now been expanded to include solutions for MRR. A basic distinction is made between two types. There are MRRs that only have shafts in one direction. This is usually the case when storage takes place on roller conveyors and the pallets abut each other in the push-through direction. If, for example, spacers are used between the pallets, the resulting gaps of max. 5 cm are not taken into account. The shafts parallel to the push-through direction must have a minimum width of 150 mm - as usual in chapter 11.5.
If the shafts are larger than 5 cm in the push-through direction, this is an MRR with longitudinal and transverse shafts. Only the design of Category III and IV racks is discussed below. Categories I and II are rare, but the concepts are described in VdS CEA 4001. Hydraulically, the racks are to be calculated with 3 x 3 x 3 = 27 sprinklers plus 260 m2 of ceiling protection.
Multi-row shelving with shafts in one direction only
In the familiar 11.5 manner, each resulting shaft is protected parallel to the push-through direction. In this direction, the maximum horizontal sprinkler spacing is 1.90 m (1.50 m for K.7). At least every second sprinkler level must be protected, whereby the distance between the sprinkler levels must not exceed 3.50 m (2.0 m for K.7) (see Figure 8).
Sprinklers must be arranged in front of the first and behind the last pallet in the direction of loading. The sprinklers must be staggered centrally across the levels.
Compared to double-deep racking, i.e. racking with three longitudinal shafts (for which the previous concepts remain unchanged), the concepts look like a tightening of the requirements, because the simplification for double-deep racking that the middle longitudinal shaft only has to be protected in every second sprinkler level (so-called shaft monitoring) does not now exist for MRR. Why? The final extinguishing by the fire department is taken into account here. As described at the beginning, the fire brigade must reach the source of the fire and extinguish it if necessary. As this can be very difficult with the large storage blocks of multi-deep racking, the aim must be to actually extinguish the fire. This can be assumed for the requirements described below.
Multi-row shelving with longitudinal and transverse shafts
There are also few surprises with this arrangement. Sprinklers must be arranged at the intersection of each longitudinal and transverse shaft. The maximum level spacing is 3.5 m (2.0 m for K.7), but no more than two levels. Sprinklers must be positioned in front of the first and behind the last pallet when viewed from each side.
Miscellaneous
Many other changes have been made in the new version. For example, the chapters on electrical alarms (14) and monitoring (19) have been revised. The requirements for electrical alarming instead of the classic water-operated alarm bell have been adapted to the terminology of the BMA world and a diagram for the control of acoustic signaling devices by a monitoring center with ring bus technology has been added.
The test facilities for flow detectors have been simplified thanks to the class resolution. In future, there will be three equivalent options here:
- Test device with a K30 nozzle behind the flow detector
- Test option via a test sprinkler according to 13.5.2
- Installation of a recognized test device (e.g. ZoneCheck, FlowGuard ...) (recognition requirement clarified in Annex I)
In Chapter 15, there is now only one table for the exposed pipes with details of the minimum wall thicknesses (see Table 2). There have also been some changes in the appendices. All tables in Annex L (ESFR) have been updated. The reference here is the regulations of NFPA 13. The conservative approach is still followed and twelve sprinklers are taken into account in the hydraulic calculation.
Appendices B and C for the classification of storage materials have been revised and updated. An attempt has been made to make the appendices easier to understand/read. The regulations on plastic pallets are new. For example, the classification according to Annex C is generally based on wooden pallets. If plastic pallets are used for materials in categories I to III, the category is to be classified one higher. Incidentally, this regulation is in accordance with prEn 12845-1. For mixed storage in goods distribution centers, freight forwarders, etc., a classification of at least HHS 4 must generally be assumed in future. A lower classification must be explicitly proven.
In addition, normative references have been updated, (typing) errors corrected and passages clarified where there have been repeated queries or discussions.