Medical Waste Room

[bluenote49]

Well here is the situation, the medical waste room in my site have a supply air of 250 l/s coming from an AHU and a 550 l/s capacity FCU unit installed inside. The room also have an exhaust register with flow of around 200 l/s. At first this room don't have a ceiling so both supply air register and exhaust register are wall mounted and the fcu is installed @ the middle of the ceiling. Now for some reason they decided to put a gypsum ceiling on it which will cover both the supply and exhaust and also the fcu. Because of that I decided to install a plenum box on the fcu supply face and then tap 400 mm diameter flexible duct on both side of the plenum connecting it to a 4- way supply diffuser having a capacity of 270 l/s maximum (1 diffuser capacity is 270 l/s) . Also we will install two pcs of 4-way diffuser for return air. So the set-up are 4 diffuser installed on the ceiling 2 for supply and 2 for return supplied by the fcu.

Now for the other supply air coming from ahu and the exhaust register were left untouched and both serving the enclosed ceiling area.

Now the question is did I do the right thing? Is having two pieces of 4 way supply diffuser connected to FCU to accommodate the 550 l/s capacity enough or too much? Is my set up correct.

What will happen with the exhaust since we did not extend it to the ceiling and left it on the wall? Can the two piece of 4 way return diffuser serve both as an exhaust and return medium?

PS: I dont have any information about the cooling requirements of the room and also I don't know if the fcu is a BACk-UP unit since there is already a supply air coming from the AHU.

Thank you

 

[Drazen]

it looks like bypass could be created between fresh and exhaust air, and exhaust air can also be drawn into return of fcu.

you could duct exhaust out of suspended ceiling, but i do not understand how waste room has positive pressure. waste room should certainly be negatively pressurized, even at cost of reducing fresh air flow.

 

[bluenote49]

Regarding about the positive/ negative pressure you are probably correct, but since I'm not the design engineer here let them worry about that heheheh. Maybe thats the requirements, I will check again the values to verify it.

Now to my other question, I'm trying to compute for the air flow that will come out from the supply diffuser but it seems the value that I'm getting is very low around single digit value lol . Can someone help me to compute the CFM flowing to the room.

Data are: FCU capacity is 550 l/s
flexible duct( 2pcs)diameter = 400 mm = 1.312 ft.
flexible duct lengt around 1.4 m = 4.59 ft
Pressure drop of fcu = 5.79 KPA