System Design Flashcards
Maximum fan diameter for HVLS fan
24’
The HVLS fan shall be centred between approximately how many sprinklers
4
The vertical distance from HVLS fan to sprinkler deflector shall be a minimum of
3 feet
What will HVLS fans do when a signal from alarm system is received
Shut down immediately
Where is the pipe schedule permitted
-additions/modifications to existing systems
- new systems under 5000sqft
-systems above 5000sqft if 50psi is available at highest elevation sprinkler
Residual pressure shall be met where
Elevation of highest sprinkler
Flow rate is measured in
GPM
Velocity is measured in
FPS (feet per second)
As pipe size decreases what happens to the velocity
Increases
Minimum required residual pressure in light hazard
15 psi
Minimum required residual pressure in ordinary hazard
20 psi
Acceptable flow at base of riser and duration of flow, supervised, light hazard
500gpm
30 minutes
Acceptable flow at base of riser and duration of flow, un-supervised, light hazard
750gpm
60 minutes
Acceptable flow at base of riser and duration of flow, supervised, ordinary hazard
850gpm
60 minutes
Acceptable flow at base of riser and duration of flow, un-supervised, ordinary hazard
1500gpm
90 minutes
Where must the residual pressure be evaluated
Highest sprinkler
Pipe sizes must be no less then ____ for steel pipe systems
1”
Pipe sizes must be no less then ____ in hydraulically calc. copper tubing and non-metallic pipe systems
3/4”
Smoother the interior of the pipe the more ____ flow will be
Smooth, laminar
The more rough that the interior is, the flow will be more ____
Turbulent
As pipe diameter becomes smaller, does pressure loss become more or less
Less due to friction
Increased velocity = increased _____
Turbulence
How does a looped system help reduce water velocity
By feeding the opened sprinkler from 2 directions
Define gridded system
Essentially series of loops in which all the branch lines serve as feed mains supplying any opened sprinkler
2 methods for determining water supply are
Pipe schedule & hydraulic calculations
What was the original method of system design
Pipe schedule
New pipe schedule systems can only be what hazard
Light & Ordinary
When are pipe schedule systems permitted with extra hazard
Only pre existing
Pipe schedule systems only permit the use of sprinklers with a k factor of
5.6
How many heads are branch lines generally limited too with pipe schedule systems
8 heads
What chapter can you find the number of heads off a pipe schedule system based off hazard
Ch.23 light and ordinary hazard
Ch.23 Annex for extra hazard
What are hydraulic calculations
Mathematical calculations to arrive at a specific flow and pressure
What systems must be hydraulically calculated
-extra hazard
-deluge systems
-high piled storage
When is the Darcy weisbach formula used
When calculating with liquids other then water (anti freeze, foam)
Anti freeze systems >40 gal
When is the hazen Williams formula used
With water (what we use)
Higher C value means
More smooth
What is the first step is system design
Occupation hazard
Quantity and combustibility of light hazard
-both low
-fires are expected to have a low HRR
Ordinary hazard Group 1 quantity and combustibility of content
Quantity is moderate
Combustibility is low
Ordinary Hazard Group 1, what is HRR and stock pile height
-Fires are expected to have moderate HRR
-stock piles do not exceed 8ft
Ordinary Hazard Group 2, quantity and combustibility of content and
- Quantity is moderate to high
- Combustibility is moderate to high
Ordinary Hazard Group 2, HRR and stockpile heights
-Moderate HRR expected
-stockpiles with content of moderate HRR is 12’
-stockpiles with content of high HRR is 8’
Extra hazard group 1, quantity and combustibility is
Very high
Dust of lint is present
Extra hazard group 1, HRR
High HRR, rapidly developing fires
What does extra hazard group 2 have which group 1 doesn’t
-Moderate to substantial amounts of flammable liquids
-shielding of combustibles is extensive
Class 1 definition
Non-combustible products stored on a wood pallet
Class 2 definition
Non-combustible products stored in a wood crate or similar combustible packaging
Class 3 definition
Products made from combustible natural products or group c plastics
Class 4 definition
Products or packaging containing group A & B plastics
When mixed commodities are present, how are the requirements determined
Based off the highest classified commodity
Hazard class and commodity class definitions are found in what chapter
Chapter 5
What is the study of water in motion
Hydrokinetics
What is pressure
Force applied to a unit of area
What is the purpose of the density method of design
Provide enough water to control a fire
How do we measure velocity pressure
Pitot tube
What happens to pressure when velocity is increased
Pressure drops (Bernoullis principle)
What is static pressure also known as
Total pressure
