Select the Right Pipe: Iplex PVC Guidelines for Suction Pipe

To download a printable copy of these guidelines click here.

It is important to note that a PVC pipe's resistance against collapsing under negative pressure is much lower than that related to it's ability to handle pressure. In addition, PVC pipe is considered unstable when subject to negative pressures - in that once it starts to buckle - it will immediately collapse.

There are a number of different types of PVC pipe, including UPVC, MPVC and OPVC. OPVC is not suited to solvent welding, and MPVC has a thinner wall than UPVC. Thus UPVC is the recommended type of PVC when utilised as suction pipe.

The following chart lists maximum recommended negative pressure that UPVC pipe should be subject to, combined with long-term minimum buckling factors of safety of 2.0 and 2.5.

This table is for PVC with a wall temperature of 25°C.

Max Neg Pressure: Nominal Sizes up to 150mm
PN Safety Factor: 2 Safety Factor: 2.5
PN6 2.8 metres 2.2 metres
PN9 10.0 metres 8.0 metres
PN12  23.0 metres 18.4 metres
     
Max Neg Pressure: Nominal Sizes 175mm and Larger
PN Safety Factor: 2 Safety Factor: 2.5
PN6 2.2 metres 1.8 metres
PN9 7.2 metres 5.7 metres
PN12 17.9 metres 14.3 metres


Where the PVC is exposed to higher temperatures, either as a result of internal water temperature or external temperature and sunlight, then you need to allow for this in your pipe selection.

This table is for PVC with a wall temperature of 40°C.

Max Neg Pressure: Nominal Sizes up to 150mm
PN Safety Factor: 2 Safety Factor: 2.5
PN6 1.4 metres 1.1 metres
PN9 5.0 metres 4.0 metres
PN12 11.5 metres 9.2 metres
     
Max Neg Pressure: Nominal Sizes 175mm and Larger
PN Safety Factor: 2 Safety Factor: 2.5
PN6 1.1 metres 0.9 metres
PN9 3.6 metres 2.9 metres
PN12 9.0 metres 7.2 metres


These guidelines were provided by Iplex Pipelines. Think Water Members stock the Iplex Pipelines range of pipes and fittings. To contact your nearest store visit our Store Locator.

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