Regulations for sprinkler systems and storage facilities

A warehouse fire can have devastating consequences, potentially leading to the closure of the business. Significant damage to property and personal injury can spell the end for a company. The environment and groundwater can be severely contaminated by firefighting water, and the air can be polluted by toxic fumes. Of course, every business wants to avoid disaster, and legislators have also enacted many laws and guidelines for fire protection. There are many fire protection measures that a company should implement. Above a certain height of shelving systems, the use of sprinkler systems is also mandatory. Used plastic storage containers must also meet certain requirements.

Most sprinkler systems in companies and warehouses are wet sprinkler systems, in which the entire pipe network is filled with water. These systems are only suitable for areas that are not at risk of frost (>5 degrees Celsius). However, there are also dry systems, pre-action sprinkler systems (VTAV) and mixed systems. In dry systems, areas at risk of frost (<5 degrees Celsius) are filled with compressed air. Only after a sprinkler button is triggered does the system fill with water. The VTAV sprinkler system is a dry system that is triggered by an automatic fire detector (smoke detector). Only then does water flow into the system, making it suitable for buildings where water damage caused by falsely triggered sprinklers must be avoided. If some areas of the building or warehouse are at risk of frost and others are not, a combination of wet and dry systems can also be used.

How is a sprinkler system constructed? Overview of components and influencing factors

Basically, the design of the sprinkler system depends on various factors such as the type of storage (rack storage with open or closed floors, block storage, etc.), the technical regulations selected, the stored goods, the building geometry, the amount of water required and the number of sprinkler heads required, and much more. The system consists of the basic elements of a pipe network (in the areas of the building to be protected), sprinklers and an independent and secure water supply. The secure water supply is a particularly important part and often has to be designed redundantly. The public water supply network, storage tanks, inexhaustible water sources and compressed air water tanks can be used for this purpose. Depending on the level of fire risk, the pipes are equipped with a certain number of sprinklers at various positions.. 

How a sprinkler activates in the event of a fire – mechanics and process explained

Each sprinkler contains a glass tube filled with a special liquid and a small amount of air. If the temperature in the warehouse or building rises, the liquid in the glass tube expands. The resulting pressure increases until all the air is absorbed. At a certain temperature (usually 68 degrees Celsius), the glass tube bursts and the sprinkler is triggered. The pressure in the sprinkler system drops and a pump starts, bringing water through the pipe system to the sprinkler. A spray from the sprinkler then extinguishes the source of the fire.

The prescribed fire protection measures are generally based on the height of the racking systems. For storage heights below 7.5 m, the racking and storage operator can usually manage without excessive fire protection measures. Above a storage height of 7.5 m, the Industrial Building Directive (IndBauRL) stipulates automatic fire extinguishing systems (sprinkler systems) or even rack sprinkler systems. ‘In storage buildings and buildings with storage areas, automatic fire extinguishing systems must be installed for storage heights (top edge of stored goods) of more than 7.5 m.’ (6.4.2 IndBauRL). From a storage height of 9 m or 12 m, new territory is entered once again. The Model Industrial Building Guideline requires more extensive fire protection requirements for high-bay racking systems with storage heights above 9 m (top edge of stored goods). However, these are not further elaborated here. The VDI 3564 guideline (Fire protection: Recommendations for high-bay racking systems) provides more specific information. It includes, for example, recommendations on the requirements and size of smoke extraction areas.

In addition to pallets, lattice boxes and containers, containers and boxes made of various materials are also used as load carriers in racking systems. The storage containers used are also subject to fire protection. The German VdS schadenverhütungs GmbH and the American industrial insurance company FM Global are leading the way in this area. If sprinkler systems are used, closed storage containers where penetrating extinguishing water cannot drain off are generally unsuitable. For this reason, containers with water drainage holes are used here, as they cascade the extinguishing water from the sprinkler systems to lower shelf levels. For the development of plastic load carriers with regard to fire protection, the FM Global Data Sheet 8-34 Protection For Automatic Storage and Retrieval Systems/ Data Sheet 8-9 Storage Of Class 1, 2, 3, 4 And Plastic Commodities and the technical VdS guideline CEA 4001 Section K.7 are used in Germany. FM Global and VdS give different indications on the design of water-permeable plastic storage containers. It is therefore essential to harmonise these directives in the medium term. The water exposure (mm/min) and flow rate are the most important design parameters for protection against fires. According to the pro-K Storage and Transport Systems working group, precise design specifications and recommendations are therefore not expedient. Depending on the country, there are other guidelines and requirements from regional insurers and institutions that must be considered for protection against fires.

Especially in the case of automatic warehouses, the guidelines of FM Global and VdS lead to conflicting goals in terms of damage prevention, label scanning and load carrier detection by light barriers.