Wet Pipe Versus Dry Pipe Fire Sprinkler Systems: Which Is Right For Your Needs?

Posted on: 2 March 2015

Sprinkler systems are proven lifesavers and can save a business large sums of money by preventing a fire from devastating facilities, equipment and inventory. However, before you install a fire sprinkler system in your business, it is helpful to understand the basic options available to you. While there are several configurations of fire sprinkler systems made by multiple manufacturers, most of the commonly-used systems can be divided into one of two categories: wet pipe and dry pipe systems. The following information provides a brief summary about the system types and gives you a short list of advantages and disadvantages for each kind:

Wet pipe systems

Wet pipe systems are the most common fire sprinkler system in use. They are called wet pipe systems because they maintain water inside the pipe network and sprinkler heads at all times. Wet pipe systems present several advantages, including:

  • Simple and less expensive – wet pipe systems are straightforward in design and operation. There are fewer components than other system types, and that makes installation and maintenance both easier and less costly.

  • Instantaneous availability – since wet pipe systems maintain a ready water supply inside the pipes and sprinkler heads, they are able to spray water on a fire immediately after activation.

  • Increased durability – since the pipes are completely filled with water that serves as a barrier against rust formation, this helps ensure that wet pipe systems are less likely to need major repairs or renovation for a significant amount of time.

Though wet pipe systems are an excellent choice for most applications, they do have a few disadvantages that should be taken into consideration:

  • Vulnerability to freezing – since wet pipe systems are constantly filled with water, they can freeze if the pipe network is placed in exposed areas. Pipe insulation can help mitigate this possibility, but it also adds to the expense of installation.

  • Need for constant pressure – wet pipe systems require a constant water supply in order to operate. In situations where water supplies can be unpredictable, this can be a problem and may require the installation of water pumps to keep the pressure at an acceptable level.

Dry pipe systems

Dry pipe systems are another option for sprinkler systems, though they are a distant second in terms of number of installations. Dry pipe systems are true to their name; the pipe network contains no water, but instead is filled with compressed air. The air prevents the water from entering the system until a sprinkler head is activated by a fire; at that point, the air escapes and releases a flapper valve that admits water into the system.

Dry pipe systems possess some distinct advantages over wet pipe systems, including:

  • Freeze resistance – since the pipes remain empty, a dry pipe system is fairly freeze-proof. This enables them to be installed in locations that would be impractical for wet-pipe systems.

  • Lower incidence of accidental discharge – in some locations, an accidental release of water from sprinkler heads can cause significant damage. The dry pipe helps prevent accidents involving sprinkler heads from being as catastrophic; the lull before water reaches the heads can provide time to shut the system down manually.

Dry pipe systems also have some disadvantages of their own:

  • Delay in water application – the lack of immediate water availability means that it can take up to a minute for dry pipe systems to begin providing water at the sprinklers. These critical seconds can allow a fire to build in intensity and size.

  • More expensive than wet pipe systems – dry pipe systems are more complex than wet pipe systems due to the need for air compressors and other components that add to the cost. In addition, dry pipe systems cost more to install and maintain.

Keep these tips in mind as you decide on the right fire sprinklers for your business. 

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