4 replies to this topic

[applepe]

Hi guys,

 

so i was tasked to do a fire water hydraulic calculation. My system is a spray nozzle/sprinkler. Based on my calculation, some of the pipe of the system are exceeding the maximum allowable velocity of 20 ft/s (Based on NFPA 20). My supervisor worked on the earlier revision and he also had one calculated pipe velocity that exceeded the limit 20 ft/s and he added note that it can be justified, so i ask him what was the justification. He said because it is still within the 10% margin of error and the service is intermittent, it can be accepted.

 

Is there any standard/source that i can refer on my document about this 10% margin of error?

Edited by applepe, 06 September 2024 - 06:58 PM.

[breizh]

Pagi 'Bu,

You need to refer to table 2-20, for the pipe minimum size, knowing that the pump can deliver 150% of the rated capacity.

I did not see anything related to intermittent!  

In my document I found 15 ft/s but that was related to the suction line.

Note: my version is 1999 lol!

To me you need to apply the rule, you may want to contact the safety bureau in JKT or consult insurance broker of the facility and your HSE manager.

 

 

If you are not compliant, you will not get the operating license.

Breizh

[applepe]

Hii.. do you mean table 2.20 on nfpa 20? Also thank you for your input. I might have to consult this further with my supervisor. 

Pagi 'Bu,

You need to refer to table 2-20, for the pipe minimum size, knowing that the pump can deliver 150% of the rated capacity.

I did not see anything related to intermittent!  

In my document I found 15 ft/s but that was related to the suction line.

Note: my version is 1999 lol!

To me you need to apply the rule, you may want to contact the safety bureau in JKT or consult insurance broker of the facility and your HSE manager.

 

 

If you are not compliant, you will not get the operating license.

Breizh

[breizh]

Hi,

Yes NFPA 20 edition 1999 table 2-20 minimum pipe size as a function of pump rating.

Breizh

[Dacs]

Hi guys,

 

so i was tasked to do a fire water hydraulic calculation. My system is a spray nozzle/sprinkler. Based on my calculation, some of the pipe of the system are exceeding the maximum allowable velocity of 20 ft/s (Based on NFPA 20). My supervisor worked on the earlier revision and he also had one calculated pipe velocity that exceeded the limit 20 ft/s and he added note that it can be justified, so i ask him what was the justification. He said because it is still within the 10% margin of error and the service is intermittent, it can be accepted.

 

Is there any standard/source that i can refer on my document about this 10% margin of error?

 

Is he an NFPA CFPS that can certify and stamp your drawings? If he's saying that, ask where in any NFPA documents where you can find this clause.