Chapter 6 - Extinguishing Systems Flashcards
Most standpipe systems are what?
Wet.
What is the major player in standpipe systems?
Head pressure.
For a pump to push water upper riser it has to do what?
Overcome the weight of the water, The head pressure.
Until a riser is completely full of water the pressure in the riser is solely due to what?
The head pressure.
Unless the riser is full of water what pressurizes the system?
Head pressure alone.
The pump can only generate riser pressure in excess of the head pressure when what?
The riser is full of water.
In years leading up to 1993, NFPA standards required standpipe outlet pressures to be between what psi?
65 to 100 psi.
What is the most common PRD?
Orifice restrictors which are simple metal discs, or washers with holes drilled in them.
What are the two ways of restricting the amount of water flowing through the outlet?
Partially obstruct the standpipe outlets waterway.
Restrict the distance the valve can be opened.
PRD’s only restrict pressure when?
When water is flowing.
PRVs limit the discharge pressure when?
Under both flowing and static conditions.
Pressure regulating valves limit the discharge pressure how?
To a specific level regardless of how much pressure is pumped into them.
Pressure reducing valves reduce pressure how?
To a certain percentage of inlet pressure.
Which valves are more efficient and more expensive?
Pressure regulating valves.
Which valve is most often used in high pressure gas applications?
Pressure regulating valve.
PRVs used for standpipe outlets are almost always what type?
Pressure reducing valves.
PRVs used as inline valves are what type?
Pressure regulating valves.
What are two type of PRV stand pipe outlets?
Factory adjusted and field adjusted
What significant problem do PRVs present to firefighter safety?
Firefighters cannot significantly increase their outlet pressure by pumping into the system.
What are PRVs usually characterized by?
A wide bonnet beneath the valve wheel.
Some other anomaly.
Some field adjustment PRVs have visible calibration numbers that are often mistaken for what?
Outlet pressure settings.
What does not exist in buildings built since 1993?
PRDs.
After 1993 outlet pressures may be what PSI?
Anywhere from 65 to 175 psi.
What needs to be known about the outlet before connecting to it?
It’s flow pressure.
Standpipes are constantly pressurized by small electric pumps called what?
Jockey pumps.
How long will the pump continue to run for if the demand is discontinued?
10 minutes.
What is the pressure at which the system’s PRVs, PRDs and sprinkler piping are calibrated?
Churn pressure.
What is the biggest factor for the difference between the rated capacity pressure and the churn pressure between pumps?
Pump size.
When a fire pump is running with no water it will build to its maximum pressure and turn water until it turns off. What is this?
Maximum pressure is the pump’s churn pressure.
What is the order of pumps in which they turn on?
Jockey pump.
Primary fire pump.
Secondary pump.
Every standpipe system has how many fire department connections outside the building
At least one.
What is the most common problem associated with pumping into standpipe systems?
Failure to actually get water into the system.
To get water through the check valve and into the system the fire department pumps must exceed what?
The system pressure.
FDC pipes tie into standpipe systems where?
Downstream of the buildings pump discharge.
All systems have what to prevent water in the system from escaping through the FDC pipe?
One way check valves.
Intoler buildings pumps for higher zones are sometimes where?
On the bottom floor of the zones they are supplying.
Using what PSI as the default figure for outlet pressure is a fairly safe bet?
120 psi.
What is the chief concern about pumping into old buildings?
Potentially fragile nature of the old fire department connection pipes.
What type of hose and where should you pump in old buildings?
Use at least 2 in hose with a solid or nozzle and calculating pump pressure to the fire floor only.
When is tandem pumping operation required?
If the needed pressure is in excess of 300 psi.
What may be the best tactic for laying out hose in the stairwell?
Connect on the floor below the fire then stretch the slack up the stairwell past the fire floor so that it will feed down.
Most sprinkler systems are what type
Wet
Where are control valves usually located?
In the stairwell where the sprinkler pipe branches off the standpipe riser.
How can excess water damage be reduced after the zones control valve is closed?
Opening the zone drain valve to dump residual water into the drain system.
What dry pipe systems are used in high value water sensitive areas?
Preaction sprinkler systems
What is a common problem with preaction systems?
The control valve is often in the protected space.
What are the two basic types of gaseous extinguishing agents?
Inert gases - argon.
Halocarbons - FM-200
When room containment is not feasible what type of extinguishing systems may be used instead of inert gases and halocarbons?
Carbon dioxide extinguishing systems.
The valves for what levels often deviate from the valve location pattern for the rest of the building?
Basement levels, the lobby and penthouse levels.
What type of sprinkler zones are fed by two separate risers with a control valve at each?
Looped sprinkler zones.
What is one very important thing that property managers can do?
Put a floor plan on the stair door of each floor.
What are two ways to partially obstruct standpipe outlet waterways
Orifice restrictors
Vane type mechanism
Where is the vane type mechanism located
Inside the valve discharge
What are the two ways of restricting the amount of water flowing through the outlet
Partially obstruct the standpipe outlets waterway
Restricted the distance the valve can be opened.
What are two ways for limiting the distance the valve can be opened
Removable pin
Mechanical stop
When a PRV is usually in full view overhead what type of system
A single PRV supplies both the sprinkler valve and the standpipe outlet
When building a makeshift standpipe what do you do
Work from the top down, four stories per 100 ft of hose
When sprinklers on multiple basement levels are fed by the city water pressure only it’s common for the valves for those floors to be what
Groups together in a single room on one of the floors
If the system pressure indicates a need for PRVs and none are apparent how do you find them
The buildings fire protection riser diagram
Three things the FDC signageshould show
The floor it serves
Whether it serves stamp pipe outlets and or sprinklers
The FD pump pressure of that zone
Four things fire protection riser diagram should show
The configuration of the system from bottom to top.
The locations of PRVs and PRDs and their pressure settings.
Any loop system sprinkler zones.
The locations of the FDC’s and the FD pump pressures for each zone
Floor plans in the fire control room should
Delineate the sprinkler zones on multiple zoned floors
Show the sprinkler valve locations
Indicate standpipe outlet locations
Show pre-action protected areas and the control valves
Show air is protected by gaseous suppression systems
Show fire pump locations
The pump can only generate riser pressure in excess of the head pressure when?
The riser is full of water. (84)
What type of inline PRV is usually in full view overhead though inconspicuous and often unnoticed
A single PRV supplies both the sprinkler valve and the standpipe outlet on each floor. (89)
What size building should departments plan and train for tandem pumping
30 stories. (101)
For a makeshift standpipe you work from which way and how many stories per 100 ft of hose
Work from the top down four stories per 100 ft of hose
Every sprinkler zone has what type of valve
Drain valve. (107)
Where are drain valves usually located
Near the sprinkler control valve (107)
In loop zones how many control valves have a drain near it
Generally only one of the control valves. (107)
We’re not in a stairwell control valves might be where (2)
Above the suspended ceiling tile often nearest stairwell door
Mechanical rooms
How can you determine how the standpipe system is zoned
This can be visually determined by locating the tops of each riser. (109)
