How to calculate stair case pressurization requirement and how to select single or multiple injection?

well it is a very long answer i'll describe it briefly then you have to search for more

- there are tow ways1- British standers 2- ASHREA standers

- in my work i prefer to use British it is easy simple and clear

- reference BS EN1-6

- choose the classification of the building from (table1)

- use (table A.3) to find out the air leakage

- as an example we will take class D system :

1. pressure difference criterion mode

- indicate no. of door and types

- calculate air leakage area as per table a.3 , pressure differential pa (all the doors are closed)

- Apply a safety factor of%

2. escape mood:

A.Velocity Criterion– (for one open door at fire floor & other at exit door

- Velocity =0. m/s , Q = V X Adoor

 * Total air flow = pressure difference mode + velocity criterion mode

- adding% as a duct leakage ------->

a.    B. Pressure Criterion– (for one open door at fire floor & other at exit door):

 n       pressure = Pa

use this equation  Qd=0. x Ad x P^1/2

* Total air flow = pressure difference mode + pressure criterion mode

- adding% as a duct leakage ------->

select the higher value from & #

- this way is almost the same for other classes may you found a little changes for no. of doors open or velocity , pressure value , so you have to check BS EN1-6 for complete image

Eng. Shareef , please add an example to explain this method ,

thank you