Hello I would like your opinion about this case please.

According NFPA 13 2019 9.4.4 Sprinklers shall be with minimun nominal K factors of K=5.6.

According NFPA 16 2019 7.6.1 Sprinkler spacing shall not exceed 100 square Feet; NFPA 16 7.2.2.1 Density shall not be less than 0.16 gpm/ft2.

So,

if I have 100 ft2 area per sprinkler and density 0.16 gpm/ft2

Q= 100 ft2 x 0.16 gpm/ft2= 16 gpm (required flow rate)

If I have a Sprinkler with K factor= 5.6 and a minimum pressure (P) of 30 psi, then the Flow (Q) is,

Q= K*P^0.5= 5.6*(30^0.5)=30.67 gpm (actual flow rate). This flow rate (30.67 gpm) is about two times the required flow rate (16 gpm).

Is possible to use a sprinkler with K factor less than 5.6?

It is to protect gasoline rail car loading area.

(image for example)

Have not seen a loading dock in a very long time

So which standard are you designing to??

The system is not using open sprinklers?????