When installing a fire sprinkler system there are three general types, wet-pipe, dry-pipe, and pre-action. A wet-pipe system contains water under pressure at all times and utilized closed sprinkler heads. A dry-pipe system is used in areas where temperatures drop to less than 40 degrees Farenheit, contains no water in the above ground piping prior to system activation, and is charged with air under pressure. The pre-action system, similar to the dry-pipe, is charged with air under pressure.
In a pre-action system the water supply is held back by a pre-action valve. This valve is connected to a supplemental detection system. Water will not enter the pipe until the detection system is activated. Once activated, the valve is released and allows water into the sprinkler piping. Water will not come from the system, until sufficient heat causes the individual sprinkler head to activate (after the pre-action valve activates, the system functions the same as a wet-pipe system). This type of operation is known as a standard or single-interlock system.
The air pressure on the pre-action valve is constantly monitored. If the pressure changes (due to leak in pipe or other issue) an alarm will sound, however, the system will not activate under this condition. The valve will remain closed, preventing water running into the system until the detection system is activated.
Another type of pre-action system known as a double-interlock system will only operate when both the supplemental detection system and a sprinkler head is activated.
These systems are commonly found in high value areas such as computer rooms, communications centers, and museums.
These systems are to be installed per the requirements of NFPA 13 and NFPA 72. The following inspections are required for system acceptance:
1. Standard hydrostatic test at 200psi for 2 hours.
2. Air pressure leakage test at 40psi for 24 hours.
3. Signage and labeling of all controls and valves to be posted.
4. Alarms monitoring the supervisory air pressure shall be tested.
5. Flow switch and water flow alarm are to be tested.
6. Operational test shall be performed, requiring the pre-action valve to trip.
7. The supplemental detection system shall be tested without operating the pre-action valve.
8. Full fire alarm system function test to be conducted.
In the early 1900's the children's story character, Dr. Doolittle, introduced us to the pushmi-pullyu. This was a gazelle-unicorn like animal having two heads each pulling in its own direction. A more contemporary example might be that of Nickelodeon's CatDog, an animal with two heads on each end, one a cat, and the other a dog.
Now the fire service has it's two headed "animal". It is a tunnel rescue vehicle, being used in Croatia, called "Merkur".
The Merkur solves a unique set of problems found only in vehicle tunnel situations. These problems include:
- poor visibility due to smoke in fire events
- little room for vehicle maneuvering
- lack of oxygen (needed to keep combustion engines running)
The Merkur has two cabs, allowing drive in both operations. It runs on electric, therefore, requiring no oxygen for operation. This vehicle is reported to be extremely simple to operate. There is no gearbox required, merely a lever indicating 'forward' and 'reverse'. Only one cab can be in operation at a time. The driver can simply walk through to the other side for operation. The Merkur is equipped with thermal imaging cameras allowing operation even under extremely low visibility conditions.
The driver gets oxygen through a personal breathing apparatus, however, the Merkur is equipped with a fresh air breathing unit, supplying oxygen to those in the vehicle. This vehicle can evacuate up to 12 people at one time, each spot has its own oxygen mask connected to the vehicles system. For firefighting, the Merkur puts out a fine water fog from the base of the vehicle and around all the tires, allowing access to the source of the fire.
This vehicle is an amazing testament to the power of creativity in the fire service. We must become more accustomed to utilizing our creative capacity in solving the problems that are unique to our departments and communities. As much as we must exercise creativity when it comes to fire ground strategy and rescue tactics, we also must utilized it in administration. We must exercise creativity in the marketing of our fire departments, and in the finances of our departments (to not just make cuts, but to create new revenues).
For more on the Merkur tunnel rescue vehicle check out Hemming Fire.
In this short video from youth speaker, Josh Shipp, he shares 3 skills that every public speaker, teacher, or trainer needs to unlearn in order to present a powerful presentation. Unlearn these skills to be more effective, and leave a lasting impact in your public education presentations.
- Stop speaking to the audience; start speaking to the individual.
- Stop caring so much about audience feedback.
- Stop thinking that you are changing lives.
