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Thread: Mixing up imperial and metric size plumbing

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    Mixing up imperial and metric size plumbing

    Here in the Philippines PVC pipes and fittings have metric sizes. Most commonly used is 50mm (1.1/2 inch) and 63mm (2 inch). Metric sizes are measured as the outer diameter.

    I want to buy/install a couple of 3-way valves from Jandy, but these have imperial sizes. E.g. the 4715 (a 1.1/2 inch valve) pipe holes are 1.7/8 inch, which is 47.625mm. Imperial pipe sizes are measured as the inner diameter of the pipe.

    So you see the problem, these valves do not fit with my pipes, so I need a kind of reducers. I searched a long time on the Internet, but can't find them.

    The solution, I guess, is to use one half of a 1.1/2 inch metric Union and combine it with one half of an imperial 1.1/2 inch Union.

    Is this a feasible solution? Any other suggestions?
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    Isaac-1's Avatar
    Join Date
    May 2010
    SW Louisiana

    Re: Mixing up imperial and metric size plumbing

    The question there would be do the threads line up?

    Another idea would be to get a short section of 1.5 inch PVC pipe from the U.S. and try to put it into a metric union fitting using some sort of gap spanning cement, afterall you are only talking about 2mm and relatively low water pressures (20-40 psi typically), or alternatively get a U.S. 1.5 inch union or adapter and bore it out to 50mm -51 mm (I assume 50mm drill bits are somewhat commonly available)

    p.s. in the US they also make special bore out bits to reuse valves, etc. that have been cemented, I have never seen one, but have read about them online, a similar metric bore out could work on the valve there, again it is only about 2 mm
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