Fire sprinklers are generally described as approximately 97% effective in controlling fires. Studies will vary, depending the author and data set that they have available to them. While this is an interesting statistic, several factors enter into this figure.
The data sources used in calculating these numbers come from reported incidents. Unfortunately, many fires are adequately controlled or extinguished, and are not included in the data used in the analysis. Also, the data set is usually a loss that meets a threshold, and is reported to an insurance company that maintains a statistical database, or is otherwise reported. The unfortunate problem is that those fires which are not controlled are detailed on page 1 of the following day's newspaper, but those fires controlled with minimal damage may not be noticed or reported at all. So, with that in mind, the effective rate of fire sprinklers is difficult to accurately quantify.
However, with all the difficulties in quantifying the failure rate, the cold hard fact is that, although rarely, fire protection failures do occur. And many times the failures could have been prevented with a minimal effort and due diligence. One of the most effective ways of determining potential failures and correcting them is through a thorough self-inspection program. The program should be conducted weekly, with some items checked on a monthly basis. This is in addition to inspection services performed by your sprinkler contractor.
Most potential latent failure conditions can be observed and corrected prior to a fire incident. If no fire occurs, any deficiency in your fire protection system continues on, day after day. But, when a fire occurs, the deficiency may have a significant impact on the outcome of the effectiveness of the fire protection system. Many of these latent failure conditions may be eliminated with regular and diligent fire protection inspection programs and a written impairment program.