What term describes the coefficient that indicates sprinkler discharge capacity?

What term describes the coefficient that indicates sprinkler discharge capacity?

• A. K-factor
• B. Discharge coefficient
• C. Orifice area
• D. Flow rate

Answer: (A)

The term used to describe a sprinkler’s discharge capacity is the K-factor. This constant, tied to the sprinkler head’s orifice size and design, is what you use in hydraulics to predict how much water a head will discharge at a given pressure. The basic relationship is Q = K × sqrt(P), where Q is the discharge in gallons per minute and P is the inlet pressure in psi. So, at the same pressure, a sprinkler with a larger K-factor will deliver more water than one with a smaller K-factor. For example, at 50 psi, Q ≈ K × 7.07; a head with K = 5 would discharge about 35 gpm, while a head with K = 8 would discharge about 56 gpm. This is why the K-factor directly indicates discharge capacity. The other terms aren’t used to denote this capacity in NFPA 13R—the discharge coefficient isn’t the standard term, and the orifice area or the flow rate itself isn’t the coefficient that describes capacity.

The term used to describe a sprinkler’s discharge capacity is the K-factor. This constant, tied to the sprinkler head’s orifice size and design, is what you use in hydraulics to predict how much water a head will discharge at a given pressure. The basic relationship is Q = K × sqrt(P), where Q is the discharge in gallons per minute and P is the inlet pressure in psi. So, at the same pressure, a sprinkler with a larger K-factor will deliver more water than one with a smaller K-factor. For example, at 50 psi, Q ≈ K × 7.07; a head with K = 5 would discharge about 35 gpm, while a head with K = 8 would discharge about 56 gpm. This is why the K-factor directly indicates discharge capacity. The other terms aren’t used to denote this capacity in NFPA 13R—the discharge coefficient isn’t the standard term, and the orifice area or the flow rate itself isn’t the coefficient that describes capacity.