Understanding In-Rack Sprinkler Systems

Today instead of talking about warehouse racking, let's talk about the topic of fire protection inside warehouses. When we talk about fire protection in warehouses, at this stage we believe that one of the most effective equipment is the in rack sprinkler system, because most warehouses don't have effective equipment to deal with fires, and simple fire extinguishers aren't very effective in dealing with the spread of fires.

So we will introduce you to the definition of in rack sprinkler, how to choose and so on, hope our content can play a certain role for your warehouse fire prevention work.

Definition of In-Rack Sprinkler

Simply put, an in rack sprinkler (in-shelf sprinkler) is a fire sprinkler system specifically designed for use in rack storage areas. It is designed to prevent a fire from occurring by quickly spraying water above or between shelves to extinguish the source of the fire. Unlike traditional sprinkler systems, the in rack sprinkler is mounted directly to the frame or shelves of the rack, allowing for more precise spraying of water to extinguish stored items within the rack.

Why use an in rack sprinkler? Because in areas of high-bay or dense storage, traditional sprinkler systems may not be able to cover every detail quickly enough, especially in the space above the shelves. The in rack sprinkler is designed to work directly in high density storage areas, increasing the efficiency of fire suppression.

The Role of the In-Rack Sprinkler

Localized fire suppression:

 The primary role of the in-rack sprinkler is to quickly suppress the spread of a fire by spraying water directly on or between racks. While a traditional sprinkler system may only spray water evenly throughout a warehouse area, the in-rack sprinkler can more precisely target the point of origin of a fire, avoiding wasted water in unrelated areas.

Reduce fire spread: 

In a high-bay storage system, goods are stacked on shelves, and if a fire breaks out, it can easily spread to higher shelves. in-rack sprinklers can target fires on different shelving levels or between shelves, reducing the rate of fire spread.

Protect high value items: 

In warehouses where valuable or flammable items are stored and where a fire could cause significant damage, the In-rack sprinkler provides additional protection for these special areas, preventing fires from spreading quickly on or within the shelves.

Improve the efficiency of your fire protection system: 

Conventional sprinkler systems cover the entire warehouse, but there may be problems with sprinkler heads not being able to extinguish the fire in time or with the water mist spreading unevenly. The in-rack sprinkler, with its precise layout, is able to take quick action in the early stages of a fire, avoiding widespread water damage and improving firefighting efficiency.

Compatibility with other fire fighting equipment: 

The in-rack sprinkler usually works in conjunction with other fire fighting equipment (e.g. smoke detectors, temperature sensors, etc.). When it detects signs of a fire, it automatically activates and sprays water to extinguish it, ensuring a fast and accurate response.

System Components of the In-Rack Sprinkler

Sprinkler Heads

This is the centerpiece of the system and is responsible for the actual sprinkler, In-rack sprinkler heads are usually mounted on the beams or vertical columns of the shelves, directly in front of the stored items on the shelves. The type of sprinkler head varies depending on the environment in which it is used, and there are usually two common types:

• Normally open nozzles: These nozzles remain closed when there is no fire and only open automatically when the temperature exceeds a set value.

• Delayed nozzle: This type of nozzle has a delay after the system is activated to ensure that water is sprayed only in the early stages of a fire and to avoid unnecessary water damage.

Piping System

Piping is the key component used to transmit the flow of water. It brings water from a fire fighting source (such as a pump or municipal water supply) to the sprinkler heads. Depending on the layout of different warehouses, piping can be horizontal or vertical to ensure that every racking area is covered. Piping usually has a corrosion-resistant design, especially in wet or potentially chemically reactive environments.

Control Valve

Control valves are used to control the flow of water on and off and usually open automatically when the system is activated. They are connected to an alarm system that automatically activates when a fire detector detects a fire, allowing water to flow through the piping system to the sprinkler heads.

Water Source

Water sources usually come from municipal water supplies, cisterns, or specialized fire fighting pools. The volume and pressure of the water source needs to be high enough to ensure that the system can provide enough water quickly in the event of a fire. Often a pump is also provided to ensure water pressure.

Alarm System

When the in-rack sprinkler system is activated, the alarm system will automatically notify warehouse management or security personnel, or even activate the fire control center. The system can give a fire alarm through sound and light to help people evacuate quickly and take emergency measures.

Water Flow Indicator (WFI)

This is a device that detects the flow of water and is used to show whether water is flowing properly into the sprinkler head. If water is not flowing as expected, the indicator triggers an alarm. This helps to identify problems in the system in time to avoid ineffective fire suppression in the event of a fire.

Support Brackets and Fittings

To ensure stable installation of sprinkler heads and pipes, in-rack sprinkler systems are usually equipped with brackets, clamps and other fittings that stabilize the pipes and sprinkler heads on the frame of the rack or between the racks. Installation requires consideration of the shelf layout and height of stored items to ensure that each area is covered.

Fire Detectors

While the in-rack sprinkler system itself does not directly detect fire, it is often linked to fire detectors (e.g. smoke detectors, heat detectors, etc.). When the detector detects abnormal temperatures or smoke, it triggers the sprinkler system to activate automatically.

Key Design Parameters for In-Rack Sprinklers

Sprinkler Type and Installation Position

• Sprinkler Type: Common sprinkler types include Standard Response and Quick Response sprinklers. The latter is designed to respond more quickly to fires and is suitable for higher-risk environments.

• Sprinkler Installation Position: The installation position of the sprinkler is crucial. Sprinklers are typically mounted on the beams of the racks or on the supports between racks to ensure coverage of every storage unit. When installing, factors like rack height, type of goods, and storage density should be considered.

Water Flow and Sprinkler Coverage Area

• Water Flow: The water flow rate for each sprinkler is a critical factor in determining firefighting efficiency. Water flow is usually measured in Gallons Per Minute (GPM). Based on the layout of the warehouse and fire load, the water flow rate of the sprinkler system needs to be accurately calculated to ensure timely fire suppression.

• Sprinkler Coverage Area: The effective coverage area of each sprinkler must be determined based on the specific layout of the warehouse. The height of the racks, arrangement, and type of goods stored will influence the sprinkler's effectiveness.

Water Pressure Requirements

In-rack sprinkler systems require sufficient water pressure to function properly. Low water pressure may result in insufficient water flow, reducing firefighting effectiveness, while high water pressure could damage sprinklers or waste water. Typically, the water pressure requirement of the system is designed based on factors such as pipe length, number of sprinklers, and the height of the floor.

System Response Time

The response time of an in-rack sprinkler system refers to the time from the occurrence of a fire to the activation of the system and the start of water discharge. The system should be designed to respond as quickly as possible, usually within a few seconds. The shorter the response time, the more effectively the fire can be contained.

Temperature Setting

Sprinklers are typically activated at a specific temperature threshold. For example, common temperature settings might be 68°C (150°F) or 93°C (200°F). When the temperature reaches the set threshold, the sprinkler’s trigger mechanism is activated, and water is discharged.

Pipe and Water Source Capacity

• Pipe Design: The diameter, material, and layout of pipes must be designed to meet the required water flow. The pipe layout should minimize water flow resistance while ensuring that each sprinkler has sufficient water pressure.

• Water Source Capacity: The water source must provide enough water to meet the needs of all sprinklers. In high-density storage environments, dedicated pumps may be required to ensure a stable water flow during a fire.

Rack Configuration and Storage Density

The layout and storage density of the racks directly affect the sprinkler system's design. High-density storage, such as narrow aisle stacking or high-rise shelving, requires special consideration to ensure sprinklers can cover every storage unit adequately. The size and shape of the goods should also be taken into account to ensure firefighting efficiency is not compromised.

System Reliability and Maintenance

The design of the in-rack sprinkler system must ensure long-term reliable operation. The system should be easy to inspect and maintain. For example, regular water flow tests, sprinkler inspections, and pipe cleaning should be included in the maintenance schedule. Additionally, the system should be freeze-proof, especially in cold regions, to prevent pipes and sprinklers from freezing.

Prevention of Obstructions and Blockages

The system should be designed to prevent the sprinklers from being obstructed by stored goods or the rack structure. In high-rise or automated warehouses, the placement of goods can interfere with the sprinkler's effectiveness. Therefore, adequate space should be left in the rack design to prevent such blockages.

Environmental and Regulatory Requirements

The design of in-rack sprinkler systems must comply with local fire safety regulations and standards, such as those set by NFPA (National Fire Protection Association) or FM (Factory Mutual) certifications. In environments where flammable materials or chemicals are stored, the design requirements are even more stringent.

Considerations When Choosing In-Rack Sprinklers

When selecting an in-rack sprinkler system, there are several key factors to consider to ensure that the system can respond effectively and safely in the event of a fire.

Warehouse Layout and Rack Design

• Rack Height: High-rise storage or ultra-high racks require sprinklers with higher water flow rates and faster response times. The height of the racks directly affects the arrangement and coverage of the sprinklers.

• Rack Spacing and Storage Density: The gaps between racks and the storage density of goods impact the installation spacing of the sprinklers. Dense storage areas require sprinklers that can precisely cover each storage unit.

• Rack Layout: The rack layout in the warehouse (such as single row, double row, narrow aisle, or wide aisle) determines the arrangement of pipes and sprinklers. When choosing sprinklers, ensure that they can cover the entire rack area, especially the blind spots between racks.

Type of Goods Stored

• Flammable Materials: If the warehouse stores flammable materials (such as paper, wood, chemicals, oils, etc.), fast-response, high-efficiency sprinklers should be chosen to quickly suppress the fire.

• Stacking Method: For high-stacked goods (such as pallets or stacked items), special attention must be given to the arrangement of sprinklers to ensure full coverage of each layer.

• Special Items: If the warehouse stores chemicals or other special items, sprinklers and firefighting methods may require custom designs. For instance, certain chemicals may need dry powder extinguishing systems or other specialized fire suppression systems.

Water Flow and Sprinkler Response Capacity

• Sprinkler Water Flow: Selecting the appropriate water flow for the sprinklers is crucial. Inadequate water flow may result in incomplete fire suppression, while excessive water flow may waste water resources and cause unnecessary damage.

• Response Speed: The response speed of sprinklers is vital in controlling the spread of fire. Quick-response sprinklers are suitable for high-fire-load areas, while standard-response sprinklers are appropriate for low-risk areas. Quick-response sprinklers can activate rapidly in the early stages of a fire to control the spread of the flames.

Temperature and Environmental Conditions

• Temperature Setting: The temperature setting of sprinklers determines the temperature at which they automatically activate. Common temperature settings range from 68°C (150°F) to 93°C (200°F). If the warehouse environment is unusually high or low in temperature, sprinklers designed for those conditions should be selected.

• Humidity: If the warehouse has high humidity (e.g., cold storage or food warehouses), corrosion-resistant sprinklers and moisture-resistant materials may be necessary. Additionally, cold storage may require sprinklers specifically designed for low-temperature environments.

• Corrosive Environments: If corrosive gases or chemicals are present in the warehouse, sprinklers and pipe materials must be chosen with corrosion-resistant properties to ensure the long-term reliability of the system.

Water Source Pressure and Pump Capacity

• Water Source Pressure: It is essential to ensure that the water source pressure is sufficient to support the normal operation of the system. If water pressure is insufficient, booster pumps may be required to increase water flow and pressure. Low water pressure may prevent sprinklers from functioning effectively.

• Pump Capacity: For large-scale or multi-story warehouses, it is necessary to select pumps that can provide sufficient water flow to ensure that all sprinklers receive timely water supply in the event of a fire.

Pipe Layout and Installation

• Pipe Design: The diameter, material, and layout of the pipes must be designed based on the warehouse area, number of sprinklers, and required water flow. The pipe layout should minimize water flow resistance while ensuring even distribution of water to each sprinkler.

• Pipe and Rack Interference: The arrangement of pipes and sprinklers must avoid interference with racks and stored goods. Sprinklers should not be obstructed by goods, and the spacing between racks should be considered to ensure effective coverage of each area.

Compliance with Fire Safety Standards

• Local Regulations: When selecting in-rack sprinklers, ensure that the system complies with local fire safety codes and standards, such as those set by NFPA (National Fire Protection Association) or FM (Factory Mutual) certifications.

• Fire Safety Testing and Certification: Choose equipment that has been certified, such as FM Approved and UL Listed, to ensure that sprinklers, pipes, and control valves meet high-quality and safety standards.

System Maintenance and Operational Convenience

• Ease of Maintenance and Inspection: Select sprinklers that are easy to inspect and maintain, allowing for regular water flow tests, sprinkler inspections, and pipe cleaning. Regular inspections help ensure the system can function reliably during a fire.

• Spare Parts and Support: Choose suppliers that provide reliable after-sales support to ensure timely repairs in case of malfunction and the availability of easily replaceable spare parts.

Fire Risk Assessment

• Fire Load Assessment: Assess the fire load in the warehouse to determine how many sprinklers are needed and the required water flow for each. High fire-load areas require more sprinklers and higher flow rates.

• Zoning: Based on fire risk assessments, divide the warehouse into areas of varying risk levels. For example, high-risk areas may require higher-specification sprinklers, while low-risk areas may use standard sprinklers.

Budget and Cost-Effectiveness

• Budget Control: When selecting an in-rack sprinkler system, choose the most suitable system within the budget. High-performance sprinklers may require a higher initial investment but can save more costs in long-term maintenance.

• Long-Term Operating and Maintenance Costs: In addition to the initial cost, consider the long-term operational and maintenance costs, including water supply, repairs, and the costs of replacing parts.

Conclusion

At the end of the article, I hope my content can help you to pick the right in rack sprinkler system when you build your warehouse.Meanwhile, if you have more needs or questions about industrial racking, you are also welcome to contact us!