Wet Sprinkler Fire Protection System

Wet Fire Sprinkler Systems – Uses, Maintenance, Advantages, Disadvantages and Comparisons

Unlike passive methods which contain a fire and stop it from spreading, an active system requires action to be taken to detect, alert and contain a fire.  An example of active fire protection methods are fire sprinkler systems.

The installation of a fire sprinkler system comprises of fire pumps, water storage tanks, control valve sets, sprinkler heads, flow switches, pressure switches, pipework, and valves. There is a lot involved in each component of a fire sprinkler system, the type of pump, hydraulic calculations, flows, pressures, quantity of sprinklers and their placement, and the list goes on.

It takes knowledge and experience to ensure this vital active method of fire protection is installed correctly.

Types of fire sprinkler systems

There are 4 types of sprinkler protection systems that are permissible for installation:

  1. Wet System
  2. Dry System
  3. Pre-action
  4. Deluge

The system is very much dependent on the type of warehouse or building and what the goods being protected consist of. For example, a warehouse storing electronic equipment such as TV’s, computers, and server rooms, need a dry fire protection system to reduce potential damage to property.

A wet system is more common than other fire sprinkler systems and we find that even in Gauteng, requests are received for wet fire sprinkler systems over other systems. In a wet sprinkler system, the pipes are filled with pressurized water so that when a fire occurs, water is immediately discharged to extinguish the fire.

When to use a wet fire sprinkler system?

According to SANS 10400 National Building Code, while not all commercial warehouses or buildings require an automated sprinkler protection system, those over 2500m2 do

Where a building is required to have a sprinkler system, any concealed space, such as a ceiling void, which has a depth that exceeds 800 mm must be equipped with a sprinkler system.

Wet fire sprinkler systems protect areas against quickly growing or spreading fires and are used in buildings where there are:

  • Combustible materials, or when thermal damage can occur quickly
  • Excessive storage heights

Industries and businesses that need a wet fire sprinkler system

  • Food and snack manufacturers
  • Processing plants
  • Packaging warehouses
  • Beverage manufacturers
  • Sugar Mills
  • Wholesalers

Advantages of a wet sprinkler system

  • One of the main advantages of a wet sprinkler system is that a fire is extinguished relatively quickly as pressurized water is released immediately as pipes are already filled with water at each sprinkler head.
  • Each sprinkler head acts independently which means that in a smaller fire, the damage caused by water is limited.  
  • It is easier to install.
  • Wet systems are more cost effective to install compared to other systems.

Disadvantages of a wet sprinkler system

One major disadvantage is that a wet sprinkler system runs the risk of freezing in temperatures less than 4.5oC. In such an event, the fire sprinkler system will not work as water within the sprinkler pipes will be frozen as well. Frozen water can cause the pipe to burst causing more damage to your facility.

Fire protection equipment used for different systems also takes into consideration the temperatures they can withstand e.g., alarm valves.

When considering the correct fire sprinkler system to install, you need to consider not only the type of goods being protected, but also the temperature that can be reliably maintained in the warehouse or facility.  

Wet vs dry fire sprinkler systems

  • Able to extinguish fires immediately – while a wet fire sprinkler system is filled with pressurised water to extinguish fires immediately, a dry system, particularly in South Africa is filled with pressurised air that keeps water at a riser. When activated, the pressure in the pipes drops, a valve opens, and water flows through the pipes and out to extinguish the fire.
  • More affordable and easier to install – dry pipe systems are more costly than a wet pipe system because they are more complex to install and maintain.

How often should a fire sprinkler system be inspected?

According to regulations in South Africa, fire sprinkler systems, including wet sprinkler systems, should be inspected twice a year by a suitably qualified individual or company. Further to this, a weekly test needs to be conducted on the sprinkler ICV and fire pumps.

Due to previous fire sprinkler quizzes conducted by Elite Fire Protection on LinkedIn, with less than half test takers answering this questions correctly, we continue to educate and create awareness on maintenance of fire equipment and remind everyone what the requirements are in South Africa to avoid or reduce the risk of malfunction of fire sprinkler systems, loss of lives and damage to property by ensuring all systems are in good working condition in accordance with the regulations. With over 50 years of combined experience, Elite Fire Protection is capable of ensuring that your fire sprinkler system is installed, maintained and serviced so that you, your building/property and your people are safe from the devastating effects of a fire.