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Sizing Compressor for Preaction System

Sizing Compressor for Preaction System

Sizing Compressor for Preaction System


Is there a way of sizing the air compressor for a pre-action system without knowing the layout of the system. I work as a plumbing engineer designing residential buildings and usually the design of the fire protection system is delegated to the contractor. However, I would like to know what size the compressor is going to be in order to size the electric circuit.

If its not possible to obtain a reasonably accurate size, is it possible to calculate a size based on the worst-case scenario?

Viking has some sizing guidelines on its website, however, since the system is yet to be designed, I would have to make several assumptions in order to calculate the volume of the system, since the size and length of the pipes are unknown.


I am a recently graduated engineer and any help would be appreciated.


RE: Sizing Compressor for Preaction System

If you use the new style low pressure valves we typically have a 110V 15A circuit for most sprinkler air compressor applications.

Can't tell you much more than that if you don't know the system piping volume as everything hinges on that value.

RE: Sizing Compressor for Preaction System

Not an engineer or designer

But unless you have some huge system, most compressors are small.

Maybe pick a medium to medium large and use those numbers.

RE: Sizing Compressor for Preaction System

The question is for a preaction system, if this is a single interlocked system the air is for supervisory air only and has nothing to do with the operation of the valve. All the air is dong is indicating the pipes are connected, no leakes in the system. I do not believe NFPA 13 has any time requirements for filling the system with air. If the valve is a double interlocked preaction valve then you must follow the requirements of the dry pipe valve for sizing and time to fill.

RE: Sizing Compressor for Preaction System

These are for residential buildings, so I am making the assumption that these dry systems would be the corridors and/or attic areas. It could also be for a parking garage.

For the ones of these that we do, we strive like crazy to keep the capacities under 750 gallons so you technically do not have to meet the 60 second trip requirement.

Travis Mack
MFP Design, LLC
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...

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