Flow Control

  • Thursday, February 23, 2017 11:17 AM
    Message # 4628867
    Deleted user

    I am very familiar with duplex being the standard for medical installations. My question is if there is a flow controller, or a flow meter with a valve, installed on an oxygen pipeline to the hospital, do there need to be two? Would having only one be a violation of NFPA 99?

  • Thursday, February 23, 2017 2:48 PM
    Reply # 4629347 on 4628867

    Good afternoon Erin.

    Do you have any additional information on the device?  A flow controller sounds like a flow limiting device (there shouldn't be one).  A flowmeter, if used, would be an optional device, and as such if installed correctly (for serviceability/with bypass) would not require redundancy.


  • Thursday, February 23, 2017 2:59 PM
    Reply # 4629353 on 4628867
    Al Moon (Administrator)

    Are we talking about Primary Source Equipment or Secondary Patient Care Equipment  

  • Thursday, February 23, 2017 5:42 PM
    Reply # 4629672 on 4628867
    Deleted user


    I don't have a specific example, I was just curious about how duplex would apply to a flow controller/flow meter and valve. This is not meant for limiting flow. This is what would allow an oxygen generator to perform at it's maximum flow, and not over, which would cause VFDs to over heat and burn out.

  • Friday, February 24, 2017 1:20 AM
    Reply # 4630160 on 4628867

    The flow controller is a flow meter. It does not do any good to duplex the flow meter when the rest of the system is simplex. Ideally you would have to have two completely separate system to consider it duplex or it can be simplex with a backup (cylinder reserve). When you need to work on the system you go on the reserve cylinders.

  • Friday, February 24, 2017 8:02 AM
    Reply # 4630611 on 4628867
    Al Moon (Administrator)

    I m not one for selling futures but.


    NFPA 99 for 2018 now has a new section for oxygen generators.

    You can review this new section for FREE on - www.nfpa.org.


    Has any one reviewed this question within the new potentially adopted code?



    Oxygen Generators will again be topic of education at the up coming annual MGPHO meeting in Las Vegas NV Oct 02,03,04 - 2017.



    The 2018 NFPA 99, also has a new chapter for Dental System #15 

  • Friday, February 24, 2017 8:53 AM
    Reply # 4632252 on 4628867

    To shove my oar in here, no standard requires a flow controller (to Al's point - I am referring to the proposed 2018).  The flow controller is a technical requirement of the technology being used. Redundancy (to Robert's point) would be a necessity if the machine depended on it for proper operation, or if it was required to properly operate the primary - secondary - reserve cascade, but not otherwise.  Many manufacturers of concentrators use a simple inline orafice or backpressure regulator to acheive the same result.


    To Robert's point, the provision of a flow limiting device within the "black box" of the concentrator supply source would be a manufacturer's decision, because it is about how the machine operates.  Flow restriction in the pipeline (e.g. patient side of the source valve) would be inappropriate, but not here.

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