The demand for e-commerce has skyrocketed among US shoppers, with around 230 million Americans making online purchases in 2021 alone. While partially fuelled by the Covid-19 pandemic, the demand isn’t expected to diminish anytime soon. As customers’ expectations for easy access and next-day deliveries continue to grow, retailers and manufacturers are rapidly shifting to systems that increase efficiency and maximize storage space.
Automatic storage and retrieval systems (ASRS) are quickly becoming the norm within e-commerce environments. While these robotized systems provide many benefits, they also present unique fire hazards. Dense storage configurations, high racking, limited access, the use of unexpanded plastic storage containers and unmanned electronic systems all pose an increased risk. ASRS can vary greatly from each manufacturer, so prescriptive building and fire codes rarely provide an exact solution – especially when working within large-scale facilities. This leads to increasing the number of sprinklers needed to protect the storage array as the ASRS is trying to fit into the prescriptive solution for which it was not designed.
FM Global Data Sheet 8-34 provides recommended guidance for protecting these racking arrangements, which involves a high number of in-rack sprinklers, multiple levels of in-rack sprinklers and vertical barriers. This solution tends to be costly for the customer, can be challenging for contractors to install sprinklers due to obstructions and tight clearances within the rack, and presents opportunities to damage in-rack sprinklers during warehouse operations like retrieving and storing shelved goods.
New challenges require custom solutions
A leading international retailer with over 200 distribution and fulfilment locations, along with their fire-protection consultant, enlisted the support of the Johnson Controls team to develop fire-protection schemes for their facilities. The goal was to reduce the number of required sprinklers and minimize renovation costs by developing schemes that have hydraulic requirements within the capabilities of their existing facilities.
The retailer needed a solution that could be repeated throughout its North American distribution and fulfilment centres. Each facility comprises densely packed racking at various heights, some soaring to almost 85ft high, and cold storage areas, all accessed by ASRS operation. Due to the immense scale of the project, minimizing labour and material costs was a necessity. Working within each facility’s existing hydraulic system was also a requirement.
The result involved custom design and testing of sprinkler-system arrangements to find just the right fit.
Using simulation to prove design effectiveness
Due to the complex storage arrangements, extensive testing was required to determine and prove effectiveness of a solution that minimizes the number of in-rack sprinklers for every potential fire scenario. However, with the associated costs and required timeline, the number of live fire tests that could be run was limited. This meant that Johnson Controls needed to use a combination of simulation, physical spray testing and live fire testing to meet the project’s needs.
Johnson Controls leveraged their extensive knowledge of fire dynamics modelling to recreate the unique layouts of the ASRS racks seen in the distribution and fulfilment centres within a virtual space. The team used models to represent three types of ASRS rack setups and predicted fire growth within each setup. Multiple simulations were run to determine optimal sprinkler locations based on different fire locations. In addition, physical spray testing was conducted to validate sprinkler selection based on spray characteristics and their location – both in-rack and on ceiling.
Fire testing was conducted using the custom sprinkler arrangements for each rack setup to prove effectiveness of these protection schemes without the use of vertical barriers. The fire tests were chosen based on the worst-case scenarios as determined by the fire modelling. The testing also allowed the customer to find a solution that was able to meet their desired hydraulic requirements.
In total, 14 full-scale fire tests split across the three different ASRS configurations were completed. The tests were conducted at Underwriters Laboratories Fire Test Lab, located in Northbrook, IL. Each test was run for approximately 30 minutes to validate the efficacy of the sprinklers and protection arrangement. Each successful test resulted in a minimal number of sprinklers operating, fire damage that was limited to the fire’s ignition area, and ceiling temperatures well below the allowable limits.
ROI-increasing Results
The result incorporated a multifaceted fire-suppression system that decreased the number of sprinklers installed by 66% and decreased in-rack branch lines by 50%, compared to FM Global DS 8-34 prescriptive solutions. The configuration also eliminated the need for vertical barriers within the racks to further reduce material cost requirements.
A variety of storage-specific Tyco sprinklers were integrated throughout the racking system and ceiling. For cold storage areas, UL Listed Tyco LFP Antifreeze was used to ensure safe and dependable operation of sprinkler systems exposed to freezing temperatures, marking a milestone use of this technology.
‘This project represents a unique application where UL Listed Tyco LFP Antifreeze was used for ASRS storage applications,’ said Manny Silva, chief engineer, Johnson Controls. ‘Overall, the achievements of the fire test programs show the impressive power of simulation and testing when paired with innovative sprinkler technology and the right team of experts. In the end, we are able to meet the customer’s expectations while providing cost savings and dependable fire protection for years to come.’
The overall fire-protection system design is estimated to save the retailer over several hundred million dollars in labour and material costs when complete. These saving can be attributed to several factors:
- The efficiency of simulation to reduce the number of live fire tests
- Reduced material costs due to less sprinklers and no vertical barriers
- Meeting the customer’s existing hydraulic requirements to eliminate the need for pump system upgrade
- Minimal maintenance requirements
For more information, go to tyco-fire.com
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