NICET WBSL Level II flashcards
NICET WBSL Level II · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Design density definition
- The minimum gpm per square foot of floor area that must be discharged over the design area; it is selected from occupancy hazard curves and sets the starting flow for hydraulic calculations.
- Remote area concept
- The hydraulically most demanding rectangular area of sprinklers assumed to operate simultaneously; its size and shape determine the total flow used in the design calculation.
- Hose stream allowance
- An additional flow added to sprinkler demand to account for fire department hose lines; typical values are 100 to 500 gpm depending on hazard classification and storage height.
- Hazen-Williams C factor
- A roughness coefficient used in friction loss formulas; 120 for unlined black steel, 130 for galvanized steel, and 150 for copper or cement-lined pipe.
- Operating pressure minimum
- Sprinklers must discharge at no less than 7 psi; below that, spray patterns degrade and coverage assumptions in the design no longer hold.
- Sprinkler coverage area
- Maximum floor area protected by one sprinkler; 225 square feet for light hazard, 130 square feet for ordinary hazard, and 100 square feet for extra hazard.
- Maximum sprinkler spacing
- The greatest distance allowed between adjacent sprinklers on a branch line; typically 15 feet for light hazard and 12 feet for ordinary and extra hazard occupancies.
- Wall distance rule
- A sprinkler must be no more than half its allowable spacing from a wall, and never more than 12 feet, to ensure the wall area receives adequate spray.
- Quick-response reduction
- A permitted decrease in remote area size, commonly 25 percent, when quick-response sprinklers are used in wet systems with ceiling heights under 12 feet.
- Slope remote area increase
- For combustible concealed or sloped ceilings at a 1.5:1 pitch, the remote area is increased by 30 percent to account for faster fire spread up the slope.
- Balanced junction rule
- Where two branch paths meet, flow splits so pressure loss is equal along each path; the layout must iterate flows until both paths converge on the same pressure.
- Velocity limit guideline
- Keeping water velocity under about 20 feet per second in mains and 15 feet per second in branches reduces noise, erosion, and excessive friction loss.
- Pump churn pressure
- The pressure a fire pump produces at zero flow; it must not exceed 140 percent of rated pressure to protect system components from overpressure.
- Standpipe outlet pressure
- The topmost 2.5-inch hose outlet must supply 100 psi residual at 250 gpm flow; lower outlets may require pressure-reducing valves to limit pressure.
- Safety margin
- A pressure cushion, typically 10 to 15 psi, added to the calculated demand so the supply can meet the system requirement with a reserve.
- Design area shape
- The remote area is rectangular, with its long dimension parallel to the branch lines, and must be at least 1.2 times the square root of the area.
- Branch line definition
- The pipe that directly feeds sprinklers along a single line; its size and length drive friction loss and determine the most remote sprinkler head.
- Cross main function
- The pipe feeding branch lines; it carries combined branch flow to the riser and is sized by total downstream demand rather than individual sprinkler flow.
- Riser definition
- The vertical supply pipe connecting the water source or pump to the cross mains; it includes the control valve, check valve, and alarm connections.
- Light hazard occupancy
- Occupancies with low combustibility and low quantity of combustibles, such as offices, schools, and churches; design density is about 0.10 gpm per square foot.
- Ordinary hazard classification
- Occupancies with moderate combustibles like mercantile and parking garages; Group 1 uses 0.15 and Group 2 uses 0.20 gpm per square foot over the design area.
- Extra hazard classification
- Occupancies with high fuel loads or flammable liquids; Group 1 uses 0.30 and Group 2 uses 0.40 gpm per square foot over an expanded design area.
- Wet pipe system
- A system with water under pressure in the piping at all times; it is the simplest and fastest-responding arrangement and allows the quick-response area reduction.
- Dry pipe system
- A system with air or nitrogen under pressure and water held back by a dry pipe valve; response is delayed and the remote area is typically increased by 30 percent.
- Preaction system
- A dry system that admits water only after a detection signal; it protects sensitive areas where accidental discharge would cause serious water damage.
- Deluge system
- A system with open sprinklers or nozzles that discharges water over an entire area upon detection; used for high-hazard or special fire protection applications.
- Flow test data
- Static and residual pressure readings at a known flow rate used to plot the water supply curve; the curve is extrapolated to estimate available flow at the required pressure.
- N1.85 graph method
- A semi-exponential plot of supply flow versus pressure used to find the point where the available water supply curve intersects the system demand curve.
- Pipe schedule method
- A prescriptive sizing approach based on tables of pipe diameter versus number of sprinklers; it is limited to small systems and cannot be used for most new designs.
- Hydraulic calculation method
- The performance-based approach that calculates pressure loss through each pipe segment and balances flows at junctions to verify the demand is met.
- Safety margin purpose
- It accounts for calculation uncertainties, pipe aging, and future changes so the system still meets demand when actual conditions differ from design assumptions.
- Pressure reducing valve
- A device installed where system pressure exceeds equipment ratings, such as lower standpipe outlets, to limit downstream pressure to a safe level.