New Domestic Demand Calculator

Things are back - now that the PE Prep season is (mostly) passed, I'm turning attention back to a backlog of fun fire protection tools and ideas to share with you.

Today's tool comes from an idea sent in by Gerald Ebeling, Owner of 3D Fire Design in Texas.

It's a new Domestic Demand Calculator - it can turn fixture counts over to a domestic demand in gpm or L/min - or you could hand count plumbing fixtures and calculate a domestic demand yourself. It works with the 2002 through 2019 editions of NFPA 13R and with both US and SI units.

TRY THE DOMESTIC DEMAND CALCULATOR

Things are back - now that the PE Prep season is (mostly) passed, I'm turning attention back to a backlog of fun fire protection tools and ideas to share with you.

This week is a new Domestic Demand Calculator - it can turn fixture counts over to a domestic demand in gpm or L/min - or you could hand count plumbing fixtures and calculate a domestic demand yourself. It works with the 2002 through 2019 editions of NFPA 13R and with both US and SI units.

Why Calculate Domestic Demand? 

For a combined service entry serving both fire suppression and domestic water needs, the flow through the combined main will include flow that is already happening on the domestic water side. Faster water movement will create more friction loss.

When a combined service is 4 or 6-inch and there's only a couple restrooms - the demand for a fire sprinkler system will likely be far higher than the domestic will ever need.

However, for smaller residential systems, the domestic demand could be as much if not more than the sprinkler demand. A combined service that serves both these purposes will need to take the domestic demand into account. 

There is a workaround for this though - automatic domestic shutoff valves can direct flow to the sprinkler system and automatically cutoff domestic demand during a fire event. If these are used, NFPA 13R says that domestic flow doesn't need to be considered.

In all other cases, NFPA 13R states that domestic flow through the combined portions of the main do need to be considered and calculated for a fire sprinkler system.

The New Tool

The Domestic Demand Calculator will be included in the next update of the downloadable MeyerFire Toolkit. For the next couple months, I'll leave it up on the site for free access for everyone. Give it a try and let me know what you think!

Thanks and have a great week!