AVOIDING WAREHOUSE DISASTERS: THE SAN ANTONIO APPROACH
FIRE PREVENTION BUREAU
The nature of the traditional warehouse changed as American cities became more decentralized after World War II. Large square-footage, single-story structures sprawled on suburban and rural landscapes replaced the multistory warehouses on downtown city streets.
The changes in size and location have been accompanied by changes in construction materials, methods of storage, and types of merchandise housed. The results have been warehouse fires that are large, severe, and the occasion for significant dollar losses.
Some of the characteristics of modern warehouses have been reflected in the model building codes. The Uniform Building Code, for example, permits “unlimited area” buildings provided that the building is one or two stories in height, fully sprinklered, classified as a B-2 “business” occupancy, and provided with 60foot clear yards on all sides. Note that the type of construction is not specified.
Most commodities stored in warehouses today characteristically are of higher value, are easily damaged, and can pose a significant fire threat. Thus, fire protection standards have been revised to incorporate the types of materials now stored and the methods of stocking them. Among these standards are NFPA Standard 231. Standard for Indoor General Storage, and NFPA Standard 231C, Standard for Rack Storage of Materials. Other standards deal with specific commodities such as rubber tires and rolled paper. In addition, model fire codes have specific chapters dealing with high-piled stock. For example, Article 81 of the Uniform Fire Code has highpiled stock requirements that encompass sprinkler systems, building and site access. 12-inch hose stations, smoke detection systems, permissible pile heights, and smoke removal systems.
Sprinkler system design criteria have taken tremendous strides to try to keep up with constantly evolving hazards. Many research dollars have been spent to update specific design details, as evidenced by the early suppression-fast response sprinkler.
Despite the revised standards, codes, and fire protection features, large-loss warehouse fires still are occurring in the United States. The San Antonio Fire Department undertook a study to find out why. Our research pointed to ignorance and a lack of communication as two of the reasons.
PROBLEMS ASSOCIATED WITH WAREHOUSE FIRES
An excellent white paper, “Before the Fire: Prevention Strategies for Storage Occupancies,” prepared under the auspices of the NFPA by a committee of fire officials, warehouse owners, and insurance authorities, identified several characteristics common to many warehouse fires. These include the following:
- The commodities stored in a warehouse change over a period of time, rendering the originally installed sprinkler system inadeqate to handle the more hazardous commodities.
- Even during the early stages, the fire is beyond the control of the plant’s fire brigade and the arriving fire department. This indicates very rapid fire spread.
- “Substandard” fire walls fail to limit spread beyond the area of origin.
- Warehouse managers do not segregate dangerous commodities such as aerosols and flammable liquids.
- 6Warehouse managers allow tem-
- porary storage of materials in the aisles.
- Storage heights are increased without verifying compatibility with the sprinkler system.
- Traditional paper and metal packaging materials have been changed to more hazardous plastic materials.
- Warehouse employees and operators are unaware of the fire hazards of the commodities they handle.
The San Antonio Fire Department identified additional problems that could lead to a warehouse disaster.
They include the following:
- Some sprinkler contractors do not ask for and document information concerning the type of materials that will be stored and the storage methods that will be used in the warehouse.
- Some warehouse owners fail to make compliance with fire codes a priority.
- Some sprinkler contractors too often underestimate the hazards posed or use the incorrect design standard.
- Sprinkler systems are designed “to the curve,” with little or no conservatism in pipe sizing.
- There is deterioration of available water supply to sprinkler systems and concurrent lack of recognition of this problem.
THE COMMODITY LETTER SOLUTION
Since information is the key to combating the problems of ignorance and lack of communication, our department set out to gather vital information in a standardized format for each warehouse. The base of our datagathering program is a five-page questionnaire that asks specific questions about the warehouse, particularly those relevant to Articles 80 and 81 of the Uniform Fire Code, the code adopted by the city of San Antonio. The Commodity Letter provides the information we need to determine the fire code requirements and serves as a record of the facility.
Printed and distributed by our department, the Commodity Letter presents nine questions pertaining to the identity and description of the stored materials. (See sidebar on page 42.) The information must be submitted on the letterhead of the new warehouse occupant listed on the questionnaire and must be signed by an authorized agent of that organization. Each page of the questionnaire contains the project’s name/number, address, and type of occupancy proposed as well as information pertaining to the review.
The Commodity Letter concludes with the following statement: “The report prepared by vour company (responding to the questions listed above) will be used as a record of your operations. Should your operations change and render the report inaccurate, you must notify the San Antonio Fire Department in writing.”
When a warehouse plan is submitted for review, our fire plan checker gives a Commodity Letter to the contractor constructing or remodeling the space, who passes it on to the tenant for completion. The plans are put on hold until the letter is returned and has been reviewed by the fire department to ensure compliance with code requirements. When a new certificate of occupancy is requested by a new tenant moving into an existing space and no construction work is involved, the fire inspector in the field gives the Commodity Letter directly to the new tenant. The certificate of occupancy is held pending a letter review.
INFORMATION ANALYSIS
If an occupant’s Commodity Letter shows that the warehouse does not contain high-piled stock (stock above 12 feet for Class I to IV commodities in racks or on pallets; 15 feet for solidpiled materials; and six feet for some Class V commodities according to the Uniform Fire Code and Standard Fire Prevention Code) and is free of hazardous materials and processes, we approve the plans. The occupant, however, must paint a red “reminder” stripe at the six-, 12-, or 15-foot level (depending on the type and stacking arrangement of the commodity). These stripes help the warehouse manager remember to comply with our stacking requirements.
If the warehouse will house highpiled stock and/or hazardous-materials operations and processes, the appropriate requirements will be given to the contractor/tenant. Fiscal restraints very often necessitate that the warehouse tenant change his operations (lower pile heights, for example) to stay “outside” of the fire code requirements and avoid the increased costs of compliance. When this happens, we require a modified Commodity Letter reflecting the changes.
One of the most important highpiled stock requirements is that of an adequately designed and installed sprinkler system. When new systems are involved, we require that full design criteria be spelled out on the sprinkler plans. We want to know every decision the sprinkler designer makes: commodity class type, aisle widths, encapsulated/nonencapsulated stock, rack types, specific design curves used, density adjustments, and so on. We compare this information with that in the Commodity Letter to ensure compliance.
In the case of an existing sprinkler system, we require that the sprinkler contractor supply us with information on the base sprinkler system design if it is not already on file. The system is compared with the needs specified in the Commodity Letter, and system upgrades (in rack sprinklers, for example) are made as necessary. In some cases, we must perform a flow test to verify that the water supply to the warehouse’s sprinkler system hasn’t deteriorated over time.
Construction is permitted to begin after the plans have been approved. The contractors call for all the required inspections including hydrostatic tests, water supply tests, standpipe flow tests, pump tests, detection system tests, smoke removal tests, and functional tests. The warehouse tenant is issued a Certificate of Occupancy after all tests and inspections have been approved.
PROGRAM EVALUATION
We consider our Commodity Letter program a success. Although the initial reaction from participants was grumbling, most have come to accept it as a necessary part of developing a code-compliant project. Without the vital information contained in the Commodity Letter, our office would be unable to perform a thorough and relatively quick plan review.
Many of our local warehouse owners and leasing agents have our letter on file to pass out to new tenants. Some even have incorporated it into their computer systems.
Our warehouse code enforcement program has led to many fruitful meetings with the warehouse industry. Our department, in conjunction with a large warehouse association, has issued a letter explaining the code requirements that focuses specifically on existing warehouse spaces.
Another program benefit has been the testing of positive-pressure fans in the warehouse environment. These fans proved valuable and permitted us to modify the fire code to allow manually operated smoke and heat vents or mechanical roof fans on new or existing warehouses. Previously such vents were permitted only on existing warehouses. In the future we plan to develop a standard screen for the Commodity Letter in our computer system and to store all of the letters received for easier access. The introduction of mobile display terminals in our fire apparatus and fire prevention vehicles eventually may enable us to access the letters from the field. A fire inspector then could verify what he sees in the warehouse during an inspection or a firefighter could learn what’s inside a warehouse on fire.
