RE: BACKFLOW PREVENTERS FOR SHELLSTOCK SHIPPING OPERATIONS

From: Gleyn Bledsoe (gleyn@nwic.edu)
Date: Fri May 04 2001 - 16:58:08 PDT

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    Backflow prevention devices are required throughout the US in many
    applications. Simple checkvalves are often used but vacuum breakers are
    preferred. Prices US run from $5.00 up but few are in the $200 range unless
    they are special application and for lines larger than 2". A solution is to
    construct a CPVC or similar material manifold from which the hoses feed.
    Then place a single device where the manifold connects to the plant water.
    An even simpler method is to set the system up where the hoses cannot reach
    the ground nor can be placed in the totes. That is, insure you have a
    vertical air gap between the end of the water supply and the containers.
    The whole idea of a backflow preventer is to prevent the hoses siphoning up
    fluids should the supply pressure drop.

    -----Original Message-----
    From: Wil [mailto:aero@citytel.net]
    Sent: Friday, May 04, 2001 4:18 PM
    To: seafood@ucdavis.edu
    Subject: BACKFLOW PREVENTERS FOR SHELLSTOCK SHIPPING OPERATIONS

    I have exhausted all resources with this one.....hopefully someone can point
    me in the right direction.
     
    I have been told by the CFIA (Canadian Food Inspection Agency) that in order
    for an existing Federally Registered Plant to start offloading farmed
    Oysters in British Columbia the following must occur:

    * The product must be added to the company QMP Plan.

    * HACCP analysis must be completed

    * Backflow Preventers must be added to each hose with in the plant and
    on the dock

     
    Now, the first two items are straight forward and therefore compliance is a
    non issue; but the backflow preventers have me stumped..... This is what I
    have found:

    * I have called many Water Valve Manufacturers and the varieties of
    backflow preventers/ vacuum breakers they have are in the 100's. Which one
    do I need? Are there any cheaper than $295 CND?

    * We have about 30 hoses that are 1" diameter and can take both a
    female and male thread part. But the cheaper backflow or vacuum breakers do
    not come in 1".

    * We have spray nozzles on each hose so they are charged at all times
    and I have been told that vacuum breakers will not work on double positive
    charges. Also that they must be installed 12" above the hose outlet.

    * All industry that I have spoken with do not use the backflow
    preventers in their plant and most have not even heard of the regulation.

    * The regulation is FIR Schedule 1 14.(11)

    If anyone can provide information I would greatly appreciate it.
     
    Thank you,
     
    Sarah



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