Dry Pipe Sprinkler Systems
There is a very literal definition of a dry pipe sprinkler system; its pipes are filled with pressurised air or nitrogen rather than water. This makes its design, mechanism and operation considerably more complex than a regular wet pipe sprinkler system, but for certain environments, a dry pipe system is very necessary and the only practical solution to the problem of fire detection and prevention.
Where are dry pipe sprinkler systems used?
A dry pipe sprinkler system is effectively the only solution in commercial or industrial areas where the ambient temperature is such that stored water in pipes may ordinarily freeze. This would create a risk of burst pipes, but also the potential inoperability of the sprinkler system. This has obvious consequences and will also create issues with the validity of the system for insurance purposes.
Therefore, a dry pipe sprinkler system should be used in areas where the average ambient temperature is below 40˚F/4.44˚C, but where a risk of fire still exists. This is typically the scenario found in places such as unheated warehouses, attics, loading docks, parking garages and commercial freezers. Dry pipe sprinkler systems are also used in places like museums or other areas where the contents of a room are valuable or water-sensitive, and any leakage from the pipes in a wet system may be undetectable, at least for a period of time.
How do they work?
A remote valve is the key to the principle of the dry pipe sprinkler system. This is held in a closed position by air pressure and therefore prevents water entering the pipes. When a fire occurs and the sprinkler heads are operated, the air escapes and the pressure drop opens the valve, this then releases the water onto the fire as per a normal wet pipe system. This activation signals an alarm and other notifications set up in the system, however, there is a delay of up to 60 seconds for the water to actually hit the fire.
Limitations of a dry pipe sprinkler system
While a dry pipe sprinkler system is a necessity in some commercial and industrial buildings, there are some disadvantages. There is additional control equipment and air pressure supply required, which increases the complexity of the design, and therefore increases installation and maintenance costs. Maintenance is also affected by the need to drain and dry the system after each operation, which also has an impact on a testing regime. Pipework in a dry pipe sprinkler system is typically steel and so is open to corrosion, there is also the possibility of moisture and condensation building up in the pipes over time, this of course can freeze up and block the sprinkler heads, so routine drying is very important.
There are several different types of sprinkler systems used for different fire prevention requirements, of course we have the standard wet pipe system, but also pre-action systems, deluge systems and foam-water systems. All of these are suitable for the environment they are designed for, and while dry pipe sprinkler systems have some issues when compared to a wet system, they are a relatively simple solution for difficult to sprinkle areas.
We have qualified and experienced heating and electrical engineers at Robinsons who can advise on the most suitable fire prevention system for your premises. This is done through understanding your business, buildings and operations and through talking to you to find a practical and affordable solution, so call us today.