How Does a Dry sprinkler System Work

We mostly have wet pipe fire-suppressing systems in homes but in bigger spaces like warehouses, workshops, and factories we have a dry sprinkler system. Let’s see how this system works and what are the advantages and complications of this system. 

Firstly, we should also know that different types of dry sprinkler systems work differently in case of a fire hazard. Although the main structure is the same throughout some of the detectors and valves are installed in addition to a security lock from sprinkling water. 

This feature helps prevent damage to equipment and storage items that are stored in warehouses, data centers, and archives. The three types of sprinkler systems are the No-Inter lock Sprinkler system, and the Single and Double Inter-lock Sprinkler system.

Let’s understand the structure and workings of a dry sprinkler system in detail. There are two halves of the system in the upper part there is air compression and atmospheric air monitored through a pressure gauge and the lower half is for water supply which is separated from the upper half through a deluge valve.

 This deluge valve has a diaphragm around the upper part which blocks the water supply ahead to the sprinklers and air pipes. In the middle, we have a solenoid valve and on the left side, we have heat detector alarms and a control panel to detect heat during a fire breakout.

The right side of the solenoid valve has a manual actuator that resets the sprinkler system after putting out the water supply through the sprinkler.

When the fire breaks the alarm rings and the automatic sprinklers that are located on top of the air compression pipes burst. The air in the compression pipes starts to move out and the pipes start to empty the air from the sprinklers.

The alarm detection detects the heat and smoke sending a message to the control panel which eventually opens the solenoid valve and the water starts to enter the pipes above the diaphragm reaching air-compressed pipes. 

The water reaches the sprinklers and as soon as the pipe is filled with water the sprinklers spray water to put down fire. When you have put the fire out the water is drained out of the pipes through the manual actuator valve and the system is reset with the air compression pipes above and the water pipe at the bottom of the system.

You have to replace the old sprinklers with the new ones in the pipelines so that the other time any accident occurs the new sprinklers get active and burst open again. The water will again move out to extinguish the fire with the same process again as mentioned above which involves the emptying of air compression and water movement in the pipes to the sprinklers. The solenoid valve will allow the water to flow upward to the sprinklers.

There is a slight difference in the Single and Double Inter-lock sprinkler system. The Single Inter-lock system has an alarm detection system that only allows the water to flow from the sprinklers if the alarm detects the smoke afterward. The air then moves out of the compression pipes and the solenoid valve opens along with the deluge valve to move upwards. The automatic sprinklers do not burst and spray water at first. The automatic sprinklers burst and the air comes out first before the water to prevent damage if they get burst by accident.

The Double Inter-lock Sprinkler system has a dry pilot valve which is at the extreme left of the solenoid valve and gets activated only after it detects fire after the opening of the solenoid. The dry pilot valve is connected with the air compression valves and the water pipelines.

As soon as the solenoid valve opens after the alarm detection, the water stays at the bottom and the diaphragm of the deluge valve opens only after the air fills in the pipe of the dry pilot valve connected to air compression pipes.

The dry pilot valve opens with the air pressure and the diaphragm of the deluge valve then allows the water to flow upwards to the sprinklers and the fire can be put down with the help of the sprinklers system. To empty the sprinkler pipes from the water with the help of a manual reset valve installed at the right side of the deluge valve.

Different types of Sprinkler heads 

There are two types of sprinkler heads in sprinkler systems. One is an open-type sprinkler and the other type is a closed-type sprinkler. The former does not have a bulb but the latter has a heat-sensitive bulb which gets bursts in case of fire.

The closed sprinkler has a direct water supply and is installed in frost-free rooms with wet sprinkler systems while the open sprinkler is used in the dry sprinkler system for rooms exposed to frost.  The sprinklers have a different type and angles of deflectors based on the area and location where they are placed.  The fastest response time index of a sprinkler is about less or equal to 50. Different shapes of sprinklers are used in different locations like kitchens and electronic spaces.

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Advantages and Disadvantages of the Dry Sprinklers System.

• They are commonly used in cold temperatures because the wet pipes freeze in extremely cold weather making it difficult to use water during the fire extinguishing process. They can also be used in attic spaces like loading docks and cold storage applications.
• Accidental water leakage in a wet sprinkler system can damage electronic equipment or storage spaces like data centers or archives but a dry sprinkler system keeps control of the damage by its inter-lock technology.
• The dry sprinkler system is much more complex and expensive than the simple or wet sprinkler system, it has a lot of operating units and valves with a constant need to keep a check on air pressure in the compression pipes through the pressure gauge.
• More testing and maintenance is required for the working of a dry sprinkler system properly because the pipes may wear out in a short period causing costly repair and replacements.
• Corrosion and leakage of metal pipes are more often in the dry sprinkler system due to air pressure in the pipes and it requires constant repair and maintenance unless a nitrogen-based gas is installed in compression pipes. Wearing out of pipes due to chemical build-up is much worse.
• Wet pipes are suitable for homes and small spaces but for spaces like electronic control rooms and storage systems, it is preferable to install the dry-sprinkler system for safety purposes preventing less damage in case of the bursting of the sprinklers due to any other reason than fire.
• Dry sprinkler systems have an increased response time than wet sprinkler systems which may result in a hazardous situation with more damage. 

All combined these advantages and disadvantages make a dry sprinkler system a suitable choice depending on where you want to install it and what sort of space is required. For electronic rooms, it is preferred to use a dry one because the web sprinkler system can cause uncertain situations in cases even if there is no fire hazard. But on an ending note be cautious about how you use the dry systems as it takes a lot of time to respond to a fire alarm and to allow the valve to supply water to the sprinkler which could even increase the possibility of more damage.