CFSA Blog

Considerations for the Protection of Compact ASRS

Author: Anthony Rago and Moriel Kaplan, Jensen Hughes, Inc.

Warehouse fires in recent years have drawn attention to the significant fire risks and fire protection difficulties posed by automated warehousing facilities. High-storage densities, limited access, electronic conveyancing systems, high racking, overpacking and overstacking can all elevate fire risk, making fire safety design more challenging. 
Automated storage and retrieval systems (ASRS) are also certainly not without significant potential fire safety risks. To facilitate the movement of products through the supply chain quickly, retailers have begun shifting to ASRS, and specifically compact ASRS. The problem is that rapid development of these systems has outpaced the current building and fire codes and associated referenced standards. Keeping this mind, several factors and fire protection requirements should be considered when a compact ASRS is being selected and installed.  

Conventional ASRS vs. Compact ASRS

Direct-to-consumer shipping has been increasing for years with the growth of online shopping and now the recent boost spurred by the COVID-19 pandemic. To keep up with order fulfillment while reducing delivery times, retailers have had to change their distribution center supply methodology. Traditionally, manufacturers would deliver products to a central retailer warehouse in pallets where they were broken down to smaller units and delivered to brick-and-mortar stores for sale. However, retailers are now shifting to methodologies that allow for single-unit order fulfillment at the warehouse location. 

This process often requires the manufacturer to supply their products in quantities less than a pallet, such that small, often individual, consumer products are arriving and leaving the warehouse almost constantly. To facilitate the movement of products through the supply chain quickly, retailers have reimagined their warehouses to become omni-channel centers, which include a shift from manual pick processes to Automated Storage and Retrieval Systems (ASRS). 

Conventional ASRS follow traditional storage configurations designed to accommodate large quantities of product or large products on racks, as defined by NFPA 13, Standard for the Installation of Sprinkler Systems. The robotic mechanism moves in the X and Y directions, down aisles and up the racks, to pick or place products that are typically palletized. The products are brought to an employee for the next steps in the distribution process.

Although ASRS have been around for decades, compact ASRS are being introduced to process smaller products. Compact ASRS are lighter-weight storage retrieval machines (typically less than 350 lbs) designed to handle smaller loads, such as cases, totes and trays. Compact ASRS are particularly useful as they reduce warehouse storage space and maximize throughput at each facility. The major differences between conventional and compact ASRS are the quantity of storage contained in a condensed floor area due to the reduction in both rack depth and aisle width, as well as the possibility for mixed commodities in a single area. 

Types of Compact ASRS

While a shuttle-type compact ASRS is used similarly to a conventional ASRS, it is tooled to handle the smaller individually packaged products that were historically manually picked from shelves in a bin or box system. The primary difference between conventional and shuttle-type compact ASRS is the size of the container being stored (pallet vs. bin size). 
This difference means that shelves can be used in lieu of racks, as defined by NFPA 13. And since aisles only need to be as wide as the storage container for operational purposes, the aisle width is also reduced. This reduction in rack depth and aisle width allows for significant condensing of the storage array. In addition, the shelving systems used with compact ASRS can be as tall as the space will permit by dividing it into vertical tiers, each containing multiple shelves much like traditional rack storage.

Grid-type compact ASRS are even more condensed than shuttle-type.  These systems are typically constructed with upright sections, which are interconnected to form vertical shafts between them.  Depending on the system, the robots run in the X and Z directions along the top, bottom, or top/bottom of the structure and then travel in the Y direction via a shaft to store or select bins/totes.  

Because the robotic pickers can move in all three planes, grid-type compact ASRS do not permit aisles or manual access into the structure. The height of the array can be as tall as the space will permit. As such, these systems allow for the most condensed storage configurations currently available. 

Involving Major Stakeholders in the Protection of ASRS

When considering the use of an ASRS, there are many stakeholders that have a vested interest in the design, operation and protection of the selected system.  As their needs often are at odds with one another, it is important to have everyone involved in discussions early. The major stakeholders from a protection standpoint are:    

End-User Inventory Manager: The products’ size, quantity, commodity classification, packaging, and throughput needed to meet demand schedules and other requirements will dictate the type and scale of the ASRS selected. The inventory manager is likely to be the individual with this information and the one who typically represents whether the project moves forward. 

Fire Protection Professional: After reviewing the operational goals and physical details of the ASRS system selected, the fire protection professional will work with the ASRS manufacturer and end user to evaluate the hazards present and then design a protection solution. They will review the applicable building and fire codes and collaborate with all stakeholders to develop a mutually agreeable basis of design for the fire protection system that does not impede the ASRS operation. The fire protection professional will also develop a fire protection response strategy to review with the local fire department whenever the basis of design or alternate method of protection scheme deems it necessary.  

Property Owner: Many property owners have minimum fire protection design requirements for their facilities. These can be as required by insurance carriers or internal corporate policies. Understanding these requirements early in the project is critical as compact ASRS will often not be addressed, but the owner will require proof of compliance with the assumed standard level of risk at project completion. Being able to discuss risk mitigation strategies will allow the fire protection professional to determine risk resolution before lease agreements are broken. 

Insurance Carriers: The property owner and end user’s insurance carriers have a vested stake in the safety of the products being stored. Should an event occur in a compact ASRS, the losses are typically greater than a traditional warehouse storage arrangement due to the condensed arrangement of products in the system. Understanding and incorporating the insurance carrier requirements early and incorporating them into the building design will avoid costly design modifications and ensure the facility can be insured. 

Authority Having Jurisdiction/Local Fire Department: As compact ASRS are relatively new to market, many authorities and fire departments do not have experience with their design, operation, or fire protection requirements and are fearful of the hazards they pose. Working together with the fire department to explain active and passive protection and develop a fire safety response plan for medical or fire emergencies is a critical step for gaining approval for the system.  

Fire Protection Considerations for ASRS Facilities

When designing the fire protection system for a facility, the following is recommended:

• Storage Height: Review whether the protection requirements for rack storage or solid-pile storage can apply. NFPA 13 provides prescriptive protection criteria for shelf storage up to 15 feet in height. Because compact ASRS are typically in warehouses with higher roof/ceilings, these systems are being designed to exceed the previsions outlined in the standard. If prescriptive protection criteria are not available, a risk analysis and/or large-scale testing should be performed to identify appropriate protection.
• Commodities: 
  • Identify the product or grouping of products that may be stored in a compact ASRS based on the retailer’s inventory. This includes flammable liquids - such as hand sanitizer - lithium-ion batteries found in smart watches, clothing and cell phones. In many compact ASRS, the commodities change frequently and are not always stocked in the same quantities or physical location.
  • Review the electronics and batteries associated with the robotics as its own fire hazard. 
• Bin/Tote Type: Evaluate the protection scheme for an ASRS that utilizes completely enclosed bins or totes differently than one that utilizes open top bins for storage. This is necessary since the sprinkler water spray pattern development, or lack thereof, is not the same.
• Building Use Group: Understand the capabilities of designed systems before assuming the available protection is adequate. Additional protection may be needed if commodities are more than the allowable quantities for a building’s defined use group.  For example, there has been an increase in compact ASRS being installed in office-use buildings and mercantile occupancies. These non-typical storage locations may not have the required protection infrastructure, such as robust sprinkler systems and fire pumps, to support the protection of compact ASRS.   
• Water Supply: Analyze the available water supply for adequate water flow and duration. If the existing infrastructure cannot provide the required flow and duration based on the protection scheme, onsite water storage would be necessary. In many cases, providing onsite water storage makes many projects physically or financially unattainable.  
• Sprinkler System: Identify required modifications to the existing installed sprinkler system or proposed design.  Understanding necessary upgrades and associated costs to the backbone of a sprinkler system to achieve higher water pressures to protect the increased storage risk will help avoid budgetary overruns.  
• In-Rack Sprinklers: Assess the available space to accommodate in-rack sprinklers. Locating sprinklers where the robotics are moving or where they are braced is not possible, so the ability to protect without using in-rack sprinklers will need to be reviewed.
• Firefighting Access: Consider access routes to the center of grid-type ASRS. As grid-type ASRS have no aisles providing access into the system, firefighting operations need to be completed from the perimeter area.  Where systems are large enough in area or the structure prevents firefighting operations from the ground, platforms maybe required at strategic locations around the perimeter to direct water hose spray into the array. Additionally, if the perimeter platforms are not sufficient, there may be a need to provide remote water monitors and video/fire detection to assist the fire department with extinguishing the fire.   

The compact nature of the storage and risk of fire requires robust fire protection systems. Fire protection strategy will vary depending on the type of ASRS selected, size (footprint), height commodity quantity and type of commodities being stored.

Available Fire Protection Standards for ASRS

There are limited fire protection standards currently available for the protection of ASRS. NFPA 13 provides options for protecting standard storage configurations, however, it does not provide specific protection requirements for compact ASRS. In specific instances, the protection schemes for the standard storage arrangements can be adapted and applied to a shuttle-type compact ASRS, as this system closely resembles back-to-back shelf storage and multiple row racks. However, NFPA 13 could not be utilized to develop a design scheme for grid-type ASRS since there are no locations to install in-rack sprinkler protection. Also, because the system uses open top bins, a ceiling-only ESFR system is not permitted.

Insurance carrier FM Global has developed FM Global Data Sheet 8-34, Protection for Automatic Storage and Retrieval Systems, based on large-scale fire testing.  It is noted that FM Global Data Sheet 8-34 does not provide sprinkler system design criteria for all types of compact ASRS, only those tested by FM Global. Care should be taken when designing to or extrapolating from this data sheet to ensure that the protection selected is adequate for the system being installed and compliant with local jurisdictional regulations.

Independently, ASRS manufacturers have initiated large-scale fire testing to determine product specific fire protection design scheme. These manufacturers use their test results along with the requirements from NFPA 13 and FM Global to develop system specific fire protection designs that may become listed or approved. Care should be taken to confirm that installation conditions meet the testing scenario prior to assuming protection of the risk is achieved.     

Common Authority Having Jurisdiction Concerns

As alluded to previously, local fire departments have an inherent stake in the design and protection of ASRS.  Compact ASRS provide a high fire load in a condensed area. The most common concerns raised by the fire department when reviewing compact ASRS include access to the ASRS system, site-specific firefighting capabilities (e.g., perimeter platform, remote water nozzle, video and fire detection), safe evacuation if conditions become unsafe and adequacy of water available to fight a fire until extinguishment.  Additional considerations may include, testing and maintenance schedules, automatic and manual shut-off, hazardous materials assessment, and more. Designing solutions for these concerns is imperative for a successful project.

Conclusion 

While conventional pallet ASRS have been around for years, the changes in shopping habits from in person to online shopping, advances in computing power and advances in robotics have allowed for the development of compact ASRS.  Developing a safe fire protection strategy for compact ASRS requires: 

• Understanding the needs of the end user, specifically the commodities and quantities thereof that are intended to be stored within the ASRS.
• Communication with the major stakeholders while understanding the fire protection design requirements requested by the insurance carrier and/or property owners. 
• Validating the fire protection design requirements based on the available standard or conducting customized fire testing for the specific system.
• Analyzing the fire protection infrastructure at the ASRS installation location to ensure that the location can supply the required fire protection features.
• Creating a fire safety plan/strategy with the responding fire department to ensure the tools required for firefighting are available.    

As compact ASRS become more common, additional codes and standards will be developed to provide prescriptive protection requirements. Until such time, the protection scheme for each ASRS system will be unique based on the project and its specific location.