Balancing Supply and Exhaust Air in Lab
Balancing Supply and Exhaust Air in Lab
(OP)
Question in a Lab installation:
Design shows 6 rooms served from 1 off 100% freash air AHU. Each room has a supply air grille and balance damper of the main duct.
The rooms are designed to be at +30pa higher than atmosphere.
The rooms are also served by 1 off exhasut fan with an exhaust air grille and balance damper on each grille.
The question is when I come to balance the air in each room, should I do both supply and exhasut at the same time. How is this possible? Should they be done at the same time. Surely the supply will be influenced by the the exhasut and vica versa in each room.
Any ideas.???
Design shows 6 rooms served from 1 off 100% freash air AHU. Each room has a supply air grille and balance damper of the main duct.
The rooms are designed to be at +30pa higher than atmosphere.
The rooms are also served by 1 off exhasut fan with an exhaust air grille and balance damper on each grille.
The question is when I come to balance the air in each room, should I do both supply and exhasut at the same time. How is this possible? Should they be done at the same time. Surely the supply will be influenced by the the exhasut and vica versa in each room.
Any ideas.???





RE: Balancing Supply and Exhaust Air in Lab
Best of luck, -CB
RE: Balancing Supply and Exhaust Air in Lab
If all your rooms are to be maintained at +30 Pa, Just keep the main supply duct VCD open(say around 80%) and control the main exhaust duct VCD so that all rooms will be balanced at the same time. It is better if you decide your initial supply VCD opening with respect to your filter pressure drops vis-a-vis the fan performance. As the filters get loaded up, you just have to increase the supply VCD opening.
If your room pressures are varying, then acheive minimum common pressure required by adjusting main dampers and then fine tuning the individual room dampers.
Regards,
Eng-Tips.com : Solving your problems before you get them.
RE: Balancing Supply and Exhaust Air in Lab
The sequence for balancing would be 1)adjust supply air volume in all rooms to design value 2)then adjust exhaust volume to obtain a pressure differential of 30 pa. 3)measure and record exhaust flow rates.
It is prefered to vary exhaust flow and keep supply volume to design value due to heat load requirements.The diffrence between supply and exhaust volume would depend on the room tightness.Another option would be to install pressure stabilizers in the wall.By adjusting the counter weight in the stabilizer damper,you can set the room to required pressure.Even if the air flow varies, the damper would self adjust to maintain the set pressure.
RE: Balancing Supply and Exhaust Air in Lab
RE: Balancing Supply and Exhaust Air in Lab
RE: Balancing Supply and Exhaust Air in Lab
RE: Balancing Supply and Exhaust Air in Lab
RE: Balancing Supply and Exhaust Air in Lab
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