Hose Reel & Hydrant Demand: engineer's guide

What this calculator does

The calculator applies code-based per-outlet flow rates and simultaneous-operation counts to return hose and hydrant demand.

Formulas used

• Hose reel: Qhose = Noutlets × 30 GPM (min 100 GPM total)
• Class I standpipe: Qsp = 250 GPM first riser + 250 GPM each additional
• Hydrant: Qhyd = Nsimultaneous × 250 GPM

Variables

• N_outlets = number of hose reels expected to operate simultaneously
• N_simultaneous = number of hydrants per AHJ, typically 2 to 4

Worked example

Scenario: Mid-rise building with 8 hose reels and 3 external hydrants, AHJ requires 2 simultaneous hydrants.

1. Hose reels: max 2 simultaneous × 30 = 100 GPM (rounded to minimum)
2. Standpipe: 250 + 250 = 500 GPM (2 risers)
3. Hydrants: 2 × 250 = 500 GPM
4. Combined non-sprinkler demand: 100 + 500 + 500 = 1100 GPM added to sprinkler demand

Common mistakes to avoid

• Adding all hose reels rather than expected simultaneous
• Missing hydrant demand for site fire loops
• Using 100 GPM for hydrant instead of 250 GPM

Frequently asked questions

Class I, II, or III standpipe?

Class I for fire department use, Class II for occupants (hose reels), Class III both.

Hose reel drum size?

25 m or 30 m of 19 mm or 25 mm hose typical, per BS EN 671-1.

Standards and references

NFPA 14, BS EN 671, BS EN 12845

Related tools on this site

• Fire Pump Sizing
• Fire Water Tank Capacity
• Sprinkler Density Coverage

Open the calculator that pairs with this guide: Hose Reel & Hydrant Demand.

Verification note

This guide is planning support only. Final design must be verified against the applicable project specification, authority requirements, manufacturer data, and the standards cited above. Consult a licensed engineer for construction-issue calculations.