John is installing a sprinkler system that makes use of a thermal-fusible link for a data center located in Canada. Which of the following statements is true of the system he’s installing?

A.
The pipes of a dry pipe system are filled with water when pressurized air within the pipes is reduced.

B.
The pipes of a preaction system are filled with water when pressurized air within the pipes is reduced.

C.
The sprinkler heads of a deluge system are wide open to allow a larger volume of water to be released in a shorter period.

D.
The pipes in a wet pipe system always contain water.

Explanation:
B: Preaction systems and dry pipe systems are similar in that the water is not held in the pipes but is released when the pressurized air within the pipes is
reduced. Once this happens, the pipes are filled with water, but it is not released right away. In a preaction system, a thermal-fusible link on the sprinkler head has
to melt before the water is released. The purpose of combining these two techniques is to give people more time to respond to false alarms or to small fires that
can be handled by other means. Putting out a small fire with a handheld extinguisher is better than losing a lot of electrical equipment to water damage. These
systems are usually used only in data processing environments rather than the whole building, because of the higher cost of these types of systems.
A is incorrect because dry pipe systems do not use a thermal-fusible link. Like preaction systems, water is not held in the pipes. The water is contained in a
“holding tank” until it is released. The pipes hold pressurized air, which is reduced when a fire or a smoke alarm is activated, allowing the water valve to be opened
by the water pressure. Water is not allowed into the pipes that feed the sprinklers until an actual fire is detected. First, a heat or smoke sensor is activated; then,
the water fills the pipes leading to the sprinkler heads, the fire alarm sounds, the electric power supply is disconnected, and finally water is allowed to flow from the
sprinklers. These pipes are best used in colder climates because the pipes will not freeze.
C is incorrect because deluge systems are not usually used in data processing environments because the water being released is in such large volumes.
Instead, deluge systems are used in environments where a fire could spread quickly. The pipes of a deluge system do not have water in them until a deluge valve
is tripped by a fire alarm system. However, the deluge valve is nonresetting, so once the valve is tripped, it stays open.
D is incorrect because a wet pipe system should not be used in a colder climate or a data processing environment, nor does it use a thermal-fusible link. Wet
pipe systems always contain water in the pipes and are usually discharged by temperature control level sensors. One disadvantage of wet pipe systems is that the
water in the pipes may freeze in colder climates. Also, if there is a nozzle or pipe break, it can cause extensive water damage. These types of systems are also
called closed-head systems.