operation theatre

[fatih75]

i have AHU 100% fresh air 5760 cfm supply three operation room with central exhaust fan 5460 3HP 3ph 220v 1750rpm put operation room negative .duct leakage repair not possible now.
what is happen if i change same ex.fan motor put with low rpm let say 1500 rpm

 

[ChrisConley]

I'd say you'd have less exhaust air.

You could use the fan laws to get an approximate reduction.

 

[fatih75]

i already use fan low put what is other effect like sp

 

[MechEngNCPE]

Do you speak english? There are 3 basic fan affinity laws:

CFM2=CFM1X(RPM2/RPM1)
SP2=SP1X(RPM2/RPM1)^2
HP2=HP1*(RPM2/RPM1)^3

 

[fatih75]

thank every body i got it

 

[AnotherEllis]

Rather than reducing exhaust, why don't you identify why you are negative? It could be as simple as dirty filters. An operation room's HVAC health should be important enough for that effort.

God forbid you have some person opened up on an operating table and your have uncorrected duct leakage/failure bringing contaminants into the space.

http://www.ellisconsultingengineers.com

 

[Waramanga]

I dont think speaking English has anything to do with the question here.
Also, how can the present duct leakage/failure bring contaminants into the space once he has the solution to his problem?
It seems that the supply air duct is leaking due to poor installation and now he needs to bring the exhaust air flow rate down to keep positive pressure in the room. I would be more concerned about losing conditions in the space as the design airflows and air changes are probably not going to be available.

 

[AnotherEllis]

Operation theaters, clean rooms and the like are designed to have a pressure relationship with adjacent areas. Outside air is a big part of this. A low outside air rate could put the operation theater negative to adjacent spaces, inviting infiltration.

Also, supply air is generally ducted to ceiling mounted HEPA diffusers. Supply air leaks in the ceiling space before the HEPAs is not getting filtered to design, and depending on the building may be leaking into the room. Unfiltered.

This is not the type of space use where a band aid is acceptable.

http://www.ellisconsultingengineers.com

 

[cry22]

Sorry Ellis, but you are kind of getting carried away with the subject.
Nothing says that the system uses laminar flow diffusers with HEPA filters. The HEPA may be at the central AHU. the HEPA is not the question in the post anyway.

In addition, the project can be in some Banana republic (AND some western republics) that has never heard of HEPA filters. I know of a few places that use window shakers for operating rooms, with no ventilation in the entire hospital. Yet, people survive just fine.
Do they have HEPA filters in those M.A.S.H units?

So "operation theatre" means "Operating Room"?

PS: "window shaker" means "Window mounted AC unit" in my neck of the wood.

 

[ChrisConley]

Yet, people survive just fine.*

*citation needed

Operating theatre design is a critical process, and proper design reduces secondary site infections, which do result in death.

I'm not saying that you are incorrect, many places operate under less than ideal circumstances, I'm just saying that implying that doing the best possible job isn't important is incorrect.

 

[AnotherEllis]

Cry22- I am operating under the assumption that we are talking about an operating room in the built environment in a 1st world country. Like the ones I design.

In real state side medical facilities designed by real PEs this would be the case. Window shaking Banana Republics need not apply.

On a central HEPA: Check ACH rates for even a Class 1000 clean room and think backwards about how big the AHU would have to be to get enough HEPA face area in it not have an overwhelming dP.

Also, I am aware of triage centers in combat situations. They have come light years forward since M.A.S.H., but I gauarantee you any surgeon faced with trying to save a life would prefer to be in an actual hospital. A less than perfect battle theater operating situation would be a necessary evil, and the question posted originally would not apply.

And thanks for the clarification. I was uncertain of what a "window shaker" was

http://www.ellisconsultingengineers.com