To calculate the flow rate of the jockey pump, it is related to one sprinkler flow rate and the leaking rates as per the figures in the NFPA (at design stage it is not possible to get that actual), would 10% considered a correct value or is it too much?

HeshamM:

I don't know that it is an exact science, but the main supplier I have used sizes the jockey pump to be about 1% of fire pump rating.  

Hesham

I don't know if I would consider the flow rate of one sprinkler to serve as the basis for the design of a jockey pump. Once a single sprinkler operates, depending on its location and required discharge pressure, the fire pump may be required to satisfy the hydraulic demand. If the building is used as a office, this method would be reasonable. If it is a warehouse protected by ESFR sprinklers I would state that the design is not reasonable.

Remember that a jockey pump is a pressure maintenance pump. Your system remains hydrostatic until a) a sprinkler operates or b) you have a leak upstream of the pump discharge.

I would defer to Travis's wisdom and ensure that the pump has a flow rate of 1% of the pump rating and has the appropriate pressure rating for your system.

The smaller the better.

I always hated those Model J pumps with the 5 HP motors and two second on/off cycle that would give a bang of water hammer.

1% sounds good.

If I have a 1000 GPM @ 14 bar Main Fire pump, does 10 GPM at such high pressure sounds O.K.?
I feel it is too little

I would be comfortable with a 10-15 gpm pump.  The jockey pump should only maintain system pressure and be able to handle "small" leaks.  The jockey pump is not intended to handle fire sprinkler discharge.  If you have a leakage rate greater than 15 gpm, then you have bigger issues than the size of the jockey pump.

I couldn't agree more with TravisMack if a 10 gpm jockey pump can't keep up then your issues are a lot bigger then the jockey pump.

10 - 15 gpm is an excellent size IMO.

To all...

What does the NFPA standard say about jockey pump sizing ?

_MJC

  

2-19* Pressure Maintenance (Jockey or Make-Up) Pumps.
2-19.1
Pressure maintenance pumps shall have rated capacities not less than any normal leakage rate. The pumps shall have discharge pressure sufficient to maintain the desired fire protection system pressure.

A-2-19
Pressure maintenance (jockey or make-up) pumps should be used where it is desirable to maintain a uniform or relatively high pressure on the fire protection system. A jockey pump should be sized to make up the allowable leakage rate within 10 minutes or 1 gpm (3.8 L/min), whichever is larger.

That is exactly what it says about jockey pumps