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  1. #1
    John Me's Avatar
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    Default Height of Vent Pipe from a Vent hood used in a Laboratory

    I have a situation. There is a laboratory exhaust hood that vents to the roof top. On the roof are several HVAC package units. In the near proximity to two of the HVAC package units is the vent stack from the Lab vent hood. Whoever put it in was 'goofy.". It sits about 1 foot off the roof with the roof wall surrounding the building being taller. Nearby sits the HVAC package units, some with an Outside Air supply too. Suspecting that some of the fumes are being recycled back into the building. We were going to extend the outside roof stack 7ft above the roof line. Now I was wondering , isn't there some sort of code or spec for having the ventstack being something like 6 ft or 9 ft above the nearest return air system? Can anyone help with this question? Location Los Angeles County, Ca
    Thank you

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  2. #2
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    Default Re: Height of Vent Pipe from a Vent hood used in a Laboratory

    Quote Originally Posted by John Me View Post
    I have a situation. There is a laboratory exhaust hood that vents to the roof top. On the roof are several HVAC package units. In the near proximity to two of the HVAC package units is the vent stack from the Lab vent hood. Whoever put it in was 'goofy.". It sits about 1 foot off the roof with the roof wall surrounding the building being taller. Nearby sits the HVAC package units, some with an Outside Air supply too. Suspecting that some of the fumes are being recycled back into the building. We were going to extend the outside roof stack 7ft above the roof line. Now I was wondering , isn't there some sort of code or spec for having the ventstack being something like 6 ft or 9 ft above the nearest return air system? Can anyone help with this question? Location Los Angeles County, Ca
    Thank you
    Yes there are specific requirements, but since you are dealing with the exhaust of possibly toxic fumes, etc., you might want to contact the county to see if they have a specific requirement. What you are venting is a little differant than gas appliance flue gas.

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  3. #3
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    Default Re: Height of Vent Pipe from a Vent hood used in a Laboratory

    This sounds like an unusual situation that may not be addressed by minimum codes and rules-of-thumb. Get a GOOD HVAC company or industrial/environmental engineer to fix the problem.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

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    Default Re: Height of Vent Pipe from a Vent hood used in a Laboratory

    Quote Originally Posted by John Me View Post
    Now I was wondering , isn't there some sort of code or spec for having the ventstack being something like 6 ft or 9 ft above the nearest return air system?

    You are probably thinking of the termination height of plumbing vents through the roof.

    From the 2006 IPC. (underlining and bold are mine)
    - 904.1 Roof extension. All open vent pipes that extend through a roof shall be terminated at least [NUMBER] inches (mm) above the roof, except that where a roof is to be used for any purpose other than weather protection, the vent extensions shall be run at least 7 feet (2134 mm) above the roof.

    When mechanical equipment is placed on the roof, the roof is now "used for any purpose other than weather protection" and the plumbing vent terminals are supposed to be 7 feet high above the roof surface.

    Regarding the exhaust vent from the lab, that would fall under the IMC.

    This is just part of the section for those exhausts.

    From the 2006 IMC.
    - SECTION 510
    - - HAZARDOUS EXHAUST SYSTEMS
    - - - 510.1 General. This section shall govern the design and construction of duct systems for hazardous exhaust and shall determine where such systems are required. Hazardous exhaust systems are systems designed to capture and control hazardous emissions generated from product handling or processes, and convey those emissions to the outdoors. Hazardous emissions include flammable vapors, gases, fumes, mists or dusts, and volatile or airborne materials posing a health hazard, such as toxic or corrosive materials. For the purposes of this section, the health hazard rating of materials shall be as specified in NFPA 704.
    - - - - For the purposes of the provisions of Section 510, a laboratory shall be defined as a facility where the use of chemicals is related to testing, analysis, teaching, research or developmental activities. Chemicals are used or synthesized on a non-production basis, rather than in a manufacturing process.
    - - - 510.2 Where required.
    A hazardous exhaust system shall be required wherever operations involving the handling or processing of hazardous materials, in the absence of such exhaust systems and under normal operating conditions, have the potential to create one of the following conditions:
    - - - - 1. A flammable vapor, gas, fume, mist or dust is present in concentrations exceeding 25 percent of the lower flammability limit of the substance for the expected room temperature.
    - - - - 2. A vapor, gas, fume, mist or dust with a health-hazard rating of 4 is present in any concentration.
    - - - - 3. A vapor, gas, fume, mist or dust with a health-hazard rating of 1, 2 or 3 is present in concentrations exceeding 1 percent of the median lethal concentration of the substance for acute inhalation toxicity.
    - - - - -
    Exception: Laboratories, as defined in Section 510.1, except where the concentrations listed in Item 1 are exceeded or a vapor, gas, fume, mist or dust with a health-hazard rating of 1, 2, 3 or 4 is present in concentrations exceeding 1 percent of the median lethal concentration of the substance for acute inhalation toxicity.



    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5
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    Default Re: Height of Vent Pipe from a Vent hood used in a Laboratory

    There are different classes of lab hoods. They also exhaust differently. Class 2, which is a fume hood sometimes runs all the time, even when there is no mixing. It helps with the lab air exchanges. Check with the lab manager for starters, they have those requiremetns. Then look at the manufacturer of the hood. The company doing the testing for air exchanges will give you some input. Put in three hoods at the cancer center, but it has been a few years. memory????

    Steve


  6. #6
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    Default Re: Height of Vent Pipe from a Vent hood used in a Laboratory

    Good post Jerry, what software do you use for all your codes. Impressive. I have always had to research.


  7. #7
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    Default Re: Height of Vent Pipe from a Vent hood used in a Laboratory

    Quote Originally Posted by Stephen Meyer View Post
    Good post Jerry, what software do you use for all your codes. Impressive. I have always had to research.
    *A bunch* of software I've purchased over the years.

    The only things I cannot put on my computer as they were not designed to be installed to a drive, CD only, are the historical UBC codes. Basically from 1922 to 1994.

    I have the NEC on my computer from 1996 to present.

    I have the
    - 1994 South Florida Building Code - Dade
    - 1996 and 1999 South Florida Building Code - Broward
    - 1994 Standard codes
    - 1997 Standard codes
    - 2003 and 2006 ICC codes (have not yet got my 2009 ICC codes, just keep putting off ordering them)
    - 2003 ICC Commentaries
    - 2001 Florida Building Code, 2001 w/2002 Revisions, 2001 w/2003 Revisions
    - 2004 Florida Building Code, 2004 w/2006 Revisions (somehow I lost my 2005 Revisions?)
    - 2004 Florida Building Code Commentaries
    - 2000 NFPA 101
    - 1999 NFPA 72
    - ADAAG
    - 2005 ASTM Standards
    - and some others ... then I have the following in printed books ...

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  8. #8
    A.D. Miller's Avatar
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    Default Re: Height of Vent Pipe from a Vent hood used in a Laboratory

    Quote Originally Posted by Stephen Meyer View Post
    Good post Jerry, what software do you use for all your codes. Impressive. I have always had to research.
    SM: Don't forget the wetware required to assimilate them all.


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