The proper design and review of fire-sprinkler systems takes months or years to learn. Avoid the following common mistakes that could get your sprinkler plan rejected.
Mistake No. 1: Improper Design Classification or Labeling
Occupancy and commodity classification definitions are found in Chapter 2 of NFPA 13, but some professionals depend too heavily on the examples provided in the appendix.
For instance, a designer may classify a retail facility with storage as an ordinary hazard facility, but when the storage exceeds 12 feet in height, it would be considered more of a storage facility. Lowe's, The Home Depot, SAM'S Club - any store in which items are stacked more than 12-feet high - have to meet a different set of requirements.
Properly labeling the plans is also paramount. It would be impossible to determine the design criteria for a facility if the plans simply state that the building is a warehouse facility, but that is a frequent situation.
Mistake No. 2: Missing or Inaccurate Water-Flow Test Data
The drawings and hydraulic calculations must include the site of the flow test and the date and time the test was conducted. The calculations must be taken to the point of the water-flow test, not to some fictitious or convenient point. For example, you can't put 100 feet in your calculations when the flow test was actually taken 500 feet from the building.
Mistake No. 3: Installing the Wrong Sprinklers
It is important that the exact sprinkler indicated on the plans and in hydraulic calculations is the sprinkler installed on the jobsite. There are numerous sprinklers available, each with a unique set of design criteria, flow-pressure requirements, spacing requirements, and specific obstruction rules. Installing the wrong sprinkler invalidates all the calculations and could put the building and its people at risk.
Mistake No. 4: Inaccurate Hydraulic Calculations
There are several areas in which mistakes can be made while performing a hydraulic calculation. You have all the pipe lengths, pipe sizes, elevation changes, fittings, and set pressure losses (such as backflow-prevention devices) that must be included in the calculations. There are many inputs, any of which could adversely affect a system.
Mistake No. 5: Missing Design Documents
Chapter 8 of NFPA 13 lists approximately 44 items that must be indicated on your plans. If one of these items is neglected or missing, it may cause a number of issues that would have to be corrected later in the field. It is far more economical to find and correct these issues early in the design process.
Richard A. Piccolo is president at B & F Technical Code Services Inc. (www.bftechcs.com), Hoffman Estates, IL.