Surge Analysis of Fire Water Piping

Surge pressures are created whenever the flow is changed abruptly and these pressures superimpose upon the operating pressure and spread throughout the whole system.

These pressure are frequently the highest and lowest that will ever be seen in a system and so become the primary design case and also the major cause of damage, leaks and downtime.

Surge also causes low pressures which means that surge pressures are the dominant cause of air valve operation, hence contamination risk, noise and odour.

A pressure rise of 10 bar can result from as little as 1 m/s which means that most pipe design pressure rating can be exceeded and most system can experience severe subatmospheric pressures.

Surge pressures are created whenever the flow is changed abruptly and these pressures superimpose upon the operating pressure and spread throughout the whole system.

These pressure are frequently the highest and lowest that will ever be seen in a system and so become the primary design case and also the major cause of damage, leaks and downtime.

Surge also causes low pressures which means that surge pressures are the dominant cause of air valve operation, hence contamination risk, noise and odour. A pressure rise of 10 bar can result from as little as 1 m/s which means that most pipe design pressure rating can be exceeded and most system can experience severe subatmospheric pressures

Then, Your Choice

WP

What do the fire suppression system specifications say?

What does your insurance company say?

What does the local code officer say?

My guess is that you will need to do a surge test, since you are modifying an existing fire suppression system.

You should know this before the first part is ordered.

Consult with a suitably qualified hydraulic engineer!!

There are other considerations, like will the existing pipe provide sufficient flow/pressure given the additional nozzles and such in place. The old system may have been "at limit" when installed, or the codes (legislative expectations) may have changed since that system was built.

Extensions would typically mean all to be upgraded to "modern practice".