<Li> Increased complexity - Dry pipe systems require additional control equipment and air pressure supply components which increases system complexity . This puts a premium on proper maintenance, as this increase in system complexity results in an inherently less reliable overall system (i.e. more single failure points) as compared to a wet pipe system . </Li> <Li> Higher installation and maintenance costs - The added complexity impacts the overall dry - pipe installation cost, and increases maintenance expenditure primarily due to added service labor costs . </Li> <Li> Lower design flexibility - Regulatory requirements limit the maximum permitted size (i.e. 750 gallons) of individual dry - pipe systems, unless additional components and design efforts are provided to limit the time from sprinkler activation to water discharge to under one minute . These limitations may increase the number of individual sprinkler zones (i.e. served from a single riser) that must be provided in the building, and impact the ability of an owner to make system additions . </Li> <Li> Increased fire response time - Because the piping is empty at the time the sprinkler operates, there is an inherent time delay in delivering water to the sprinklers which have operated while the water travels from the riser to the sprinkler, partially filling the piping in the process . A maximum of 60 seconds is normally allowed by regulatory requirements from the time a single sprinkler opens until water is discharged onto the fire . This delay in fire suppression results in a larger fire prior to control, increasing property damage . </Li>

How does a pre-action fire sprinkler system work