Fire Protection Flashcards
Conduction
Q = K(A/L)(T(1) - T(2)) K: thermal conductivity L: thickness A: area of conduction
Convection
Q = HAdeltaT H: heat transfer coefficient Q: rate of convective heat transfer A: area of transfer DeltaT: temperature difference
Frictional Losses in a Piping System
P(d) = (4.52 * Q^1.85) / (C^1.85 * d^4.87) P(d): pressure loss due to friction, psi/ft Q: flow rate, gpm d: pipe diameter, in C: coefficient of friction
Pressure & Flow Through an Orifice
P = (Q/K)^2 P: pressure, psi Q: flow rate, gpm K: the K-factor, a parameter of the orifice
Vapor Volume
V = (SG * 111) / VD V: volume of vapor generated per gal liquid, ft^3 G: liquid specific gravity VD: vapor density
Specific Volume
The volume of vapors generated by the evaporation of a given volume of liquid, often expressed as m^3/L.
Weight of Air
.075 lb / ft^3
Weight of Water
8.33 lb / gallon
Vρ
“V and lowercase Greek letter rho,” vapor density compared to air; where air = 1.
Specific Gravity
Density of a liquid compared to water; water = 1
Velocity Pressure, Pipe Diameter, & Flow Rate
P(v) = Q^2 / 891d^4
P(v): velocity pressure, psi
Q: flow rate, gpm
d: pipe diameter, in
Halon Codes
carbon atoms, # flourine atoms, # chlorine atoms, # bromine atoms.
e.g., Halon 1202 can be made from methane (CH4) by substituting two hydrogen with two flourine and the other two hydrogen with bromine.
Flow Rate and Pressure of Two Piping Systems
Q(1) / Q(2) = √P(1) / √P(2)
Extinguishers: Dry Powder vs Dry Chemical
Dry powders are used to extinguish metal fires, but they can only extinguish the metal fires for which they were designed.
Dry chemicals can be used on A, B, and C fires.
Mnemonic: dry powder-coated metal
