A variation of the dry-pipe system is the pre action system which has a two phase response to a fire

Question3Marks: 2A(n) _________________________ system has pressurized water in all pipes and has some form ofvalve in each protected area.

Fire suppression systems fall into three fundamental categories: wet pipe, dry pipe, and deluge. Pre-action fire sprinklers fall right in between all of these.

Pre-action pipes start out as dry pipes; they hold water back using an electronic “pre-action" valve. This system requires two events to happen before any sprinklers discharge:

1. The pre-action valve will only activate when an independent fire detection system detects a fire. Upon alert, the pre-action valve releases, water flows in, and the system essentially becomes a wet pipe system.

2. Now that water is on deck, one or more individual sprinkler heads need to release to engage and discharge water.

Pre-action systems offer several advantages. It’s not uncommon for sprinkler heads to be falsely triggered. Accidental activation often results in costly, irreversible property and water damage. The two-event discharge requirement adds an elevated level of protection from such inadvertent discharges. The use of pressurized air or nitrogen in the piping system allows for the easy detection of leaks.

With over 130 years of experience, Wormald is the specialist in fire safety in Australia.

Traditional “wet pipe” sprinkler systems offers protection against fires, but can result in water damage if unnecessarily activated in sensitive areas, such as; computer rooms, museums, libraries or refrigerated areas. Single or double interlock preaction systems can be configured to allow time for alternative fire extinguishment before the Water Deluge Systems are activated.

According to your specific requirements, fire hazard and fuel load, Wormald can design a system that is activated by wet or dry pilot sprinklers or electric detectors and can be automatic or manually operated. Having designed and installed hundreds of systems for applications large and small, Wormald can work with you to deliver a solution to meet your needs and budget.

Single Interlock Preaction Systems

Single interlock preaction systems protect areas where there is danger of serious water damage that might result from damaged automatic sprinklers or piping. Typically, such areas include computer rooms, storage areas for valuable artifacts, libraries and archives. Preaction systems are effectively used to protect properties where a prealarm of a possible fire condition may allow time for fire extinguishment by alternate suppression means, prior to a sprinkler discharge. In the event the fire cannot otherwise be extinguished, the preaction sprinkler system will then perform as the primary fire protection system.

Double Interlock Preaction Systems

Double interlock preaction systems are designed for applications such as refrigerated areas that require the maximum degree of protection against an inadvertent operation that could result in unnecessary flooding of the sprinkler system piping.

In order to actuate the double interlock preaction system, two independent events, caused by a fire condition, must occur. The sprinkler system piping must lose air or nitrogen pressure due to the operation of one or more sprinklers, and the deluge releasing panel must energize and open the solenoid valve upon the operation of a fire detection device. The double interlock system will operate only when both the dry pilot actuator and the solenoid valve are open at the same time. Opening of the dry pilot actuator only (for example: a forklift truck accidentally dislodges a sprinkler) or of the solenoid valve only (for example: accidental operation of an electric manual pull station) will cause an alarm, and will not trip the system or flood the sprinkler system piping.