Table of air openings for generators 1

[AusLee]

Hello,

I am looking for a table or a formula to calculate the openings in the structure of a generator room for air inlet and outlet.

Caterpillar generator sheets does not specify this, example:
Cooling System
Ambient air temperature : 43 Deg C
Air flow restriction (system) : .18 kPa
Air flow (max @ rated speed for radiator arrangement): 692 m³/min
Engine coolant capacity: 156.8 L
Radiator coolant capacity: 204.0 L
Engine Coolant capacity with radiator/exp. tank: 360.8 L

nothing in square maeters. Same thing with Kohler and Cummins: they specify the required square meters only for some generators but not for all.

Can you please point me to somewhere i can find this chart?

Thank you.

 

[waross]

No chart but my personal rules of thumb that work for me.
All the generators that I have installed have pusher fans. The air exits the front of the radiator. I duct the radiator directly to the outside with no reduction in the cross section.
The discharge opening is the same area and usually the same dimensions as the active area of the radiator.
I try to have the air inlet opening twice the area as the active area of the radiator.
I often do not have control over the construction and I am sometimes over-ruled by customers and/or builders who have never installed a gen-set before and think that their guess is as good as anyone's. I have seen inlet openings less than 50% of the radiator openings. The worst examples were lightly loaded sets and were able to survive. Many of the sets I install are residential standby sets and are sized for starting large A/C units. The sets typically run at a very light loading which is forgiving of a poor air supply design.
yours

 

[BJC]

Search Caterpillar for LEBE 1924[1] PDF
It the electric power and installation guide.
408 pages, your answers are in there.

 

[itsmoked]

How would you know the installations worked waross? You could never get through the door to observe one of those starved generators.[flush]

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[AusLee]

Thank you for the replies.

For the outlet, one supplier here showed me that he goes 1.5 times the surface fo the radiator. I think it all depends on the power of the ventialors as well.

BJC: can you please give me the full link, i searched caterpillar without finding this document.

Thank you.

 

[BJC]

Go to advanced search

http://www.cat.com/cda/servlet/cat.vce.servlet.VeritySearchServlet?m=37400&x=7&advancedSearch=true

and search for:

"Electric Power Application and Installation Guide"

 

[waross]

Hi itsmoked.
That's a valid observation.
I have heard of issues where that happened.
However, with a small set and 30% of radiator area for incoming air the door opens easily. I equate air shortage problems with engine overheating. If the engine temperature is normal, I consider the air flow to be adequate, at that particular loading.
I use unpowered louvers or unpowered dampers whenever possible. If powered dampers are required, I use "power to close, spring return to open" dampers.
My favorite story is the one where the designer used "power to open" dampers on an air intake for a large generator. The designer, owners rep. and the contractors rep. were in the generator room for the first test. The generator was started and blew a lot of the air out of the room. I was told that all the dirt and light scraps on the floor were swirling through the air and, as you said, they couldn't get the door open. It didn't take too long for the voltage to come up and the damper motors to get the dampers open but it was an interesting wait.

 

[AusLee]

Thanks BJC, i got it and it seems nice.

Thanks all.