Snow --> AHU intake

[ROCHESTER]

I have the following system:
[ol]
[li]BL-1, BioPharm, cell culture production.[/li]
[li]50,000 S.F. suite of clean rooms[/li]
[li]Two ~ 40,000 CFM AHUs; 100% outside air[/li]
[li]100% exhaust with no heat/cooling recovery
[/ol]

The New England facility was commissioned last fall. Under certain powdery snow conditions, and we had snow drawn into the intake and foul the pre-filters. The engineering firm hired to fix this is proposing a "snow eliminator"

http://www.mistop.com/snostop.shtml

The price estimate came in a > $100,000. Questions:

[ol]
[li]Does a BL-1 facility REQUIRE 100% outside air design?[/li]
[li]Is a desiccant wheel usable with a BL-1 AHU[/li]
[li]If a desiccant wheel can't be used, wouldn't an air-to-air heat exchanger provide the same function as the snow eliminator and save energy at the same time?[/li]
[li]What's a ball-park capital cost for a 40,000 CFM air-to-air heat exchanger unit?[/li]
[/ol]

 

[mizzoueng]

Yes, a BL1 facility does require 100% OA. You cannot recirculate exhaust air in any BL facility.

What kind of AHU do you have? I would imagine that the AHU you have is a typical AHU with 2 stage HEPA filters. You could use a desiccant wheel, but cost would probably be about the same once you added in modifing the existing AHU and checking flow rates to make sure you have not lost any.

Yes. Another thing you can do is make the intake opening of the hood parallel with the ground and maybe go buy filter media that you can place on the intake hood to catch the snow during the winter.

I wouldn't think more than 30K fully installed. There's not a lot of material here. Look here for more info:

http://www.lytron.com/standard/exch...at_exchanger&gclid=CMP6tI-ly4UCFRrCPgodYVsQ1A

 

[SAK9]

BL1 does not require 100% fresh air.100 % frsh air is mandatory for BL3 only.Please refer to CDC/NIH guidelines for detailed explanations.However your process may require 100% fresh air in order to avoid cross contamination or any other issues.So try and establish the requirement with the process engineers.

As for froast on the filters,you need to install a frost prevention coil on the air intake.No filter or screens are to be installed ahead of the froast coil as it will be clogged up soon.Usually froast coils have wide fin spacing or no fins at all to prevent the build up of ice

 

[ROCHESTER]

SAK9.

Thank you very much for the help, much appreciated.

Craig