Megan L. Asbrock PE MSFPE
Chemical
- Sep 7, 2021
- 3
thread184-354824
folks anything associated with a fire pump starts with NFPA 20. there are specific sections dedicated to vertical turbines ...the pit is just the supply ...the critical design component is the draw down within the pit. draw down will be something that depends on how fast the water can rush in to the space as its getting sucked out and physically its the difference between the static water level (no pump running) and the steady state water level during pump operation. you do not want the drawing down to be large in other words ....the static water level must be within the min NPSH value for the specific pump
so if you have a tiny , obstructed pit you should probably expect to see a substantial draw down ... and thus need to be very very sure that the pump is spec'd correctly and the min head always remains below the min water level observed once it is at steady state operation.
in other words the risk of pump not operating as intended increases as you shrink your pit.... so provide as much unobstructed clearance around the intake as you can....and in NFPA 20 there are specific performance and design requirements. use the find feature when you open the PDF of the code and type vertical turbine ....thats the easiest way
folks anything associated with a fire pump starts with NFPA 20. there are specific sections dedicated to vertical turbines ...the pit is just the supply ...the critical design component is the draw down within the pit. draw down will be something that depends on how fast the water can rush in to the space as its getting sucked out and physically its the difference between the static water level (no pump running) and the steady state water level during pump operation. you do not want the drawing down to be large in other words ....the static water level must be within the min NPSH value for the specific pump
so if you have a tiny , obstructed pit you should probably expect to see a substantial draw down ... and thus need to be very very sure that the pump is spec'd correctly and the min head always remains below the min water level observed once it is at steady state operation.
in other words the risk of pump not operating as intended increases as you shrink your pit.... so provide as much unobstructed clearance around the intake as you can....and in NFPA 20 there are specific performance and design requirements. use the find feature when you open the PDF of the code and type vertical turbine ....thats the easiest way
