Determination of Sprinkler Flow, Fire Cabinet and Hose Flow Requirements and Fire Pump Capacity of a Medium-Hazardous Business According to NFPA 13 Standard:

Example Business:

A metal processing factory with an area of 2000 square meters

Medium hazard class

Storage and production areas available

Sprinkler Flow Requirement:

According to the NFPA 13 standard, the sprinkler flow requirement of a medium-hazardous business is determined as 0.60 L/s/m² (0.15 gpm/ft²). In this case, the sprinkler flow requirement of the sample business is:

Sprinkler Flow = Area * Flow Density = 2000 m² * 0.60 L/s/m² = 1200 L/s

Sprinkler System Pressure Requirements:

Minimum pressure: 7 bar (100 psi)

Maximum pressure: 14 bar (200 psi)

Fire Cabinet and Hose Flow Requirements:

According to the NFPA 13 standard, in a medium-hazardous business, there should be a fire cabinet every 30 meters and a hose of at least 25 meters in each cabinet. The flow rate requirement of the hose is determined as at least 250 L/min (66 gpm).

Number of Fire Cabinets = Area / Fire Cabinet Range = 2000 m² / 30 m = 66.67

Number of Fire Cabinets (Rounded) = 67

Total Hose Flow = Number of Fire Cabinets * Hose Flow = 67 * 250 L/min = 16750 L/min

Fire Cabinet Hose Pressure Requirements:

Minimum pressure: 4 bar (60 psi)

Maximum pressure: 10 bar (150 psi)

Fire Pump Capacity:

The fire pump must have the capacity to provide the necessary flow rate and pressure to the sprinkler system and fire cabinets. In this case, the capacity of the fire pump is:

Fire Pump Capacity = Sprinkler Flow + Fire Cabinet Flow = 1200 L/s + 16750 L/min = 2875 L/min

Fire Pump Pressure Requirements:

Minimum pressure: Sprinkler System Minimum Pressure + Fire Cabinet Hose Minimum Pressure = 7 bar + 4 bar = 11 bar

Maximum pressure: Sprinkler System Maximum Pressure + Fire Cabinet Hose Maximum Pressure = 14 bar + 10 bar = 24 bar

Note:

This calculation is made for an example business. The sprinkler flow rate, fire cabinet and hose flow needs and fire pump capacity of a real business should be calculated in detail according to the NFPA 13 standard and the special conditions of the business.

The values used in the calculation are taken from the 2022 version of the NFPA 13 standard and general technical values.

The actual system design and equipment selection should be done by a licensed engineer.