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run on underground drainage pipe

Discussion in 'Building Regulations and Planning Permission' started by dan smith, 23 Mar 2016.

  1. dan smith

    dan smith

    28 Feb 2016
    Thanks Received:
    United Kingdom
    Does anyone know wot setting I need on my level for a underground drainage pipe? 0.9/1.8?? Any help would be much appreciated

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  3. KenGMac


    24 Aug 2010
    Thanks Received:
    United Kingdom
    dan smith, god evening.

    As I recall we are talking about an old fashioned term "Self Cleansing Velocity" of drains.

    I would imagine that there is a load of information on the net on the above??

    In general terms the so called fall on a 4 Inch Dia. pipe was taken a 4/1 as far as a 6 inch Dia. pipe was concerned the fall would be simply 6/1

    The key information above is that if you search for self Cleansing Velocity

    Here is a bit from somewhere?

    Most private housing drainage is nominal100mm pipes laid in an even bed of 10mm pea gravel. Pipes should always be laid with an even fall. The standard gradient for 100mm pipes is a fall of 1:80. A gradient of 1:100 can be acceptable on long straight runs. If flows are likely not to exceed 1l/sec then the gradient of a 100mm pipe should increase to 1:40. Some may ask why a pipe with less flow needs a steeper gradient; this is because fluid runs down wet pipes easier than dry pipes and in low flow situations much fluid is used in creating the wetted area on the pipe and hence there can be a tendency for effluent to sit in the pipe. The self-cleansing velocity of a pipe is regarded as 0.7 l/sec.

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