Combining Lab Extract or General Ventilation Duct with Local Exhaust Ventilation Duct
Combining Lab Extract or General Ventilation Duct with Local Exhaust Ventilation Duct
(OP)
Can anyone advise me if it is acceptable practice to combine Lab Extract or General Ventilation duct, with an LEV exhaust duct?
I'm conducting a review of proposed LEV installations in a new Hospital under construction, and most of the exhaust ducts for the various LEV's appear to take additional connections from lab extract ducts and in some cases from general ventilation extract.
I've checked all the regs I can find including information in HTM 03-01, HSG 258, NFPA 45 & 91, SMACNA, ANSI/AIHA Z9.5, OSHA and ASHRAE and as detailed as these regs all appear to be, none of them addresses this question.
LEV's I've dealt with in the past had dedicated exhaust ductwork and fan installations with no additional connections to either lab extract or general ventilation. Common sense tells me this is wrong because of the potential for cross contamination, but as the old adage goes - 'never assume, check!'
In the absence of hard evidence that the installations are non compliant, I'll be unable to flag the concern.
I'm conducting a review of proposed LEV installations in a new Hospital under construction, and most of the exhaust ducts for the various LEV's appear to take additional connections from lab extract ducts and in some cases from general ventilation extract.
I've checked all the regs I can find including information in HTM 03-01, HSG 258, NFPA 45 & 91, SMACNA, ANSI/AIHA Z9.5, OSHA and ASHRAE and as detailed as these regs all appear to be, none of them addresses this question.
LEV's I've dealt with in the past had dedicated exhaust ductwork and fan installations with no additional connections to either lab extract or general ventilation. Common sense tells me this is wrong because of the potential for cross contamination, but as the old adage goes - 'never assume, check!'
In the absence of hard evidence that the installations are non compliant, I'll be unable to flag the concern.





RE: Combining Lab Extract or General Ventilation Duct with Local Exhaust Ventilation Duct
RE: Combining Lab Extract or General Ventilation Duct with Local Exhaust Ventilation Duct
RE: Combining Lab Extract or General Ventilation Duct with Local Exhaust Ventilation Duct
RE: Combining Lab Extract or General Ventilation Duct with Local Exhaust Ventilation Duct
@urgross - I'd noted the NFPA 45 comment about manifolding from the same Lab. But my concern lingers largely because of the difference between the term 'exhaust' and the term 'extract'. Further, I also have a mental block over the term 'Laboratory Unit'. I may be looking way too deep at the question but in essence, I can't get past the idea that this should really mean manifolding the extracts from one space.
To clarify my concern a little - one example here, I'm looking an LEV duct that combines three fume cabinet exhausts. All perfectly good to me. But then downstream, that duct accepts connections from a variety extract ducts from the likes of a Waste Room, a Cold Storage Room and a Growth Production Room. Now to my mind they simply cannot be considered as being the same Lab Unit. Or am I overdoing things here?
RE: Combining Lab Extract or General Ventilation Duct with Local Exhaust Ventilation Duct
other than that, cross-contamination exists if it can be proven, which is likely not the case with local exhaust.
RE: Combining Lab Extract or General Ventilation Duct with Local Exhaust Ventilation Duct