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Discuss Garage washing in the Water Regulations area at

  1. Chalmers7

    Chalmers7 New Member

    Guys, loking for advice not sure on this item, a client wants to install wash points for a car dealership forecourt he is suggesting he wants to run the main below ground and come to a low level chamber with his double reg etc, is this acceptable or should they rise from below ground level?
  2. ShaunCorbs

    ShaunCorbs Trusted Plumber GSR Top Contributor!!

    If it's sealed I can't see a problem
  3. Chalmers7

    Chalmers7 New Member

    as in within a sealed chamber? is a RPZn valve regulation, just that these are a nightmare and no one to service them.
  4. chris watkins

    chris watkins Plumber

    If your Bye-laws are the same as our Regs I would say that from what you describe greater protection would be required than that provided by a double check valve.

    What do you mean by a low level chamber ? is the outlet going to be below ground level (or even less than 150mm above)

    What are they going to connect to this outlet ? will it just be a hose for washing the cars would there be chemicals added ?

    Where would the back flow protection device be located ?

    Need a bit more info first.
  5. chris watkins

    chris watkins Plumber

    RPZ's must be above ground as they must have an AA air gap to there discharge pipe.
    and they are only good for Cat 4 hoses at ground level would I am sure be Cat 5.

    Break tank with AB air gap & booster pump to feed them all would be my solution.
    • Like Like x 1
  6. snowhead

    snowhead Well-Known Member

    I'd say they are looking for just below ground accessible chambers so they can drive over them.

    As Chris, Break tank and boost pump only.

    See also;

    Where the tap is intended for car washing, degreasing plants, industrial areas
    or where there are likely be chemicals (including insecticides)etc., the water company may deem the risk to be Fluid Category 4 and an RPZ Valve (BA device) could beused.
    The RPZ valve would ideally be inside the building,
    otherwise it should be frost protected in an insulated cabinet.
    Where there is no building the Arrow Valves Standpipe model SPBAprovides a solution.
    The regulations are concerned with the minimum level of protection and it is acceptable to provide a higher level of protection e.g. sing a dedicated Break Tank with Type AB air gap can be used for all applications without conditions.
    In situations where it is not practical to use a standpipe, the Arrow Valves below ground hose union tap assembly model HUBG provides an alternative.
    Since the outlet is clearly less than 150 mm above the ground, it is necessary to supply this from a dedicated Break Tank with type AB air gap (“Boost-A-Break” -model BTAB) –not directly from a supply pipe.
    • Like Like x 1
    Last edited: Nov 19, 2015
  7. chris watkins

    chris watkins Plumber

    Oooo new sheet from Arrowvalves, I like the little L/L hose outlets they are new!!
  8. Chalmers7

    Chalmers7 New Member

    Guys some great comments and the link was really helpful, they were looking for this connection to be in a chamber below ground level so they can drive over it, likewise I thought a break tank would be required as the level of cover that's required. the utility company will advise on what level of cover so its worth the call.
  9. YorkshireDave

    YorkshireDave Member

    Hmm. How about putting a large break tank (such as used to boost poor incoming mains) fed via a pt 2 valve with twin non return valves off main and then pumping to these outlets. I'm assuming its only going to one or two at a time. That way no RPZ valve requirement! Higher up front cost but low cost of ownership and simply removed when reqd... Just my two penneth.
  10. tamz

    tamz Guest

    In a past life i used to do forecourt work for Gulf in Scotland and it was all inspected and signed off by Scottish water. All carwashes except for the jet wash machines were cistern fed and pumped from a tank house.
    Jet wash machines were fed from a washing machine valve and a double check and whatever else gubbins was in the machine (i never hung around long enough to see exactly what was in there)
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