NICET WBSL Level I flashcards
NICET WBSL Level I · Build recall with a focused review session.
33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Sprinkler discharge formula
- Q = K times the square root of p, where Q is flow in gpm, K is the sprinkler discharge coefficient, and p is pressure in psi at the sprinkler.
- Hazen-Williams friction loss
- Friction loss per foot of pipe equals 4.52 times Q to the 1.85 power, divided by C to the 1.85 power times d to the 4.87 power, with Q in gpm and d in inches.
- Light hazard density
- Minimum design density of 0.10 gpm per square foot over a 1,500 square foot remote area, with maximum sprinkler spacing of 15 feet and 225 square feet per head.
- Ordinary Hazard Group 1
- Design density of 0.15 gpm per square foot over a 1,500 square foot remote area, with maximum spacing of 15 feet and 130 square feet per sprinkler.
- Ordinary Hazard Group 2
- Design density of 0.20 gpm per square foot over a 1,500 square foot remote area, with maximum spacing of 15 feet and 130 square feet per sprinkler.
- Extra hazard spacing limit
- Maximum sprinkler spacing of 12 feet and 100 square feet per sprinkler, with densities starting at 0.30 gpm per square foot over a 2,500 square foot remote area.
- Remote area reduction
- A 25 percent reduction in remote area is allowed only with listed quick-response sprinklers under ceilings 10 feet or less, and never reduces the required density.
- Schedule 40 pipe limits
- Pipe schedule method caps 1 inch at 2 sprinklers, 1.5 inch at 5, 2 inch at 10, 2.5 inch at 30, 3 inch at 60, and 4 inch or larger at 100.
- C factor values
- Hazen-Williams roughness coefficient C is 120 for black steel and galvanized steel, 150 for cement-lined ductile iron, and 140 for copper tubing.
- Balancing a sprinkler
- Increase the flow of a lower-pressure head until its pressure equals the junction pressure, using Q new equals Q old times the square root of pressure new over pressure old.
- Wet-pipe valve arrangement
- A wet-pipe riser requires a main control valve, a check valve, and an alarm check valve, plus a waterflow switch or pressure switch that activates the alarm.
- Dry-pipe air pressure
- Air pressure in a dry-pipe system is typically maintained about 20 psi above the trip pressure of the dry-pipe valve, and a quick-opening device is needed above 500 gallons.
- Design area definition
- The hydraulically most demanding area of sprinkler operation, measured in square feet, whose size depends on hazard class and sprinkler type.
- Density definition
- The minimum flow rate in gpm per square foot that must be delivered over the design area, set by the occupancy hazard classification and commodity.
- Sprinkler K factor
- A number expressing the discharge coefficient of a sprinkler; a larger K means more flow at the same pressure, and K is listed on the sprinkler.
- Hydraulic junction point
- The node where two or more pipe paths meet; the most demanding path sets the pressure, and other paths are adjusted to match it.
- Supply curve
- A plot of available pressure versus flow at the base of the riser, derived from a flow test and adjusted for elevation and friction losses.
- Demand curve
- A plot of required pressure versus flow for the sprinkler system, plotted from the hydraulically most remote sprinkler back to the water supply.
- Safety margin
- The difference between available supply pressure and system demand pressure at the same flow; a positive margin is required for the design to be acceptable.
- Elevation pressure change
- Pressure changes by 0.433 psi per foot of elevation, added when flowing downward and subtracted when flowing upward in a hydraulic calculation.
- Flow test data
- Static pressure, residual pressure, and pitot flow measured at a hydrant; these three values define the water supply curve for the calculation.
- Velocity limit in pipe
- Design velocity in sprinkler piping should not exceed 20 feet per second in most branch lines and 32 feet per second in mains and risers.
- Branch line maximum length
- The distance from the cross main to the most remote sprinkler on a branch line; longer branch lines increase friction and pressure demand.
- Sprinkler coverage area
- The floor area protected by one sprinkler, calculated as spacing along the branch times spacing between branch lines, and limited by hazard class.
- Deflector distance
- Sprinkler deflectors must be a minimum of 1 inch below the ceiling for standard spray sprinklers, and closer for concealed or recessed types.
- Dry-pipe design area increase
- Dry-pipe and preaction systems require the remote area to be increased by 30 percent because of the larger volume of gas to be expelled.
- Pump churn pressure
- The maximum pressure a fire pump produces at zero flow; it must not exceed the rated pressure by more than 140 percent for the system components.
- Standpipe flow requirement
- Class I standpipes require 500 gpm for the most remote riser and 250 gpm for each additional riser, up to a total of 1,250 gpm.
- Hose stream allowance
- Additional flow in gpm added to the sprinkler demand for manual hose lines, set by hazard class and duration, and included in the supply calculation.
- Water supply duration
- The time the supply must sustain the demand, typically 30 to 120 minutes depending on hazard, and longer for extra hazard occupancies.
- Pipe schedule method
- A prescriptive sizing method that limits the number of sprinklers per pipe size; it is not permitted for new systems above certain sizes without hydraulic calculation.
- Hydraulic calculation report
- A document listing each node, flow, pressure, pipe size, length, and fitting equivalent length, plus the supply and demand curves and the safety margin.
- Equivalent length of fittings
- The friction loss of a fitting expressed as a length of straight pipe of the same size, added to the actual pipe length in the calculation.