Parkade makeup air

[LevMyshkin]

Hello,

In a parkade exhuast system that serves only 1-2 storeys (enclosed below grade) we would typically use the entry ramp as the source of makeup air (we're not in a climate that needs gas fired makeup air systems). This assumes that the entry ramp security gate has a high free area. Chatting with a colleague recently we got into a discussion on what the maximum face velocity for the makeup air through the entry ramp should be. I did some more digging and I'm getting information ranging between 50-500 fpm (taking into consideration any obstruction from the security gate).

What do you use as a maximum face velocity for the makeup air through a parkade entry ramp and why?

Thanks,

P. Myshkin

 

[nuuvox000]

I tell our clients that the gates have to be those linkages that are almost completely freely open.
If you wanted to calculate something, you might have to do some testing with an existing gate that's already installed.

If I had to think of a way to calculate it, I'd probably calculate it based on the pressure drop, not the fpm; that would help me size my fan. Find the approximate free area of the gate in question and compare it to something that already has pressure drop data (like a perforated grille or a louver). Then I'd find something that was comparable to the gate in terms of free area per gate area.
e.g., a grille with 40% free area might be comparable to a gate that's about 40% free area as far as pressure drop.

 

[LevMyshkin]

Thanks, that's a better way of thinking about it for sure.