Easy install guide: Metric Compression 75mm to 125mm




In the plumbing game not all pipes align or match in size!


Got two pieces of pipe you need to join and they aren’t the same diameter?  PLASSON compression reducer fittings can easily join two lengths of different-size metric HDPE pipe. Reducing sets also help you modify PLASSON fittings to connect pipe of different sizes.

Compression reducer fittings match common pipe sizes and are usually PN16 rated.

‍Compression reducers are suitable for water and other similar fluids with pressures up to 16 bar, however, this varies with the ambient temperature and temperature of the pipe contents.

A compression reducing tee fitting is used to tee off a metric HDPE pipe and add a smaller size outlet. Compression reducing tees are often used to supply water or other fluids off a main pipeline because the smaller off-take provides less flow than the original pipeline.

PLASSON reducing sets are available in the 110mm to 20mm range. They can be inserted into will existing PLASSON metric compression fittings to reduce the size of the outlet whilst maintaining pressure ratings and eliminating leak risk.

Increase flexibility of existing fittings – convert tees or elbows to another size

Reduction without threads – eliminate leak risk and maintain pressure rating

Utilises the Plasson Captive O-Ring system – no movement and high compression

Poly to Copper adaptor kits available

Compression reducers are suitable for outdoor use and are resistant to etching by numerous chemical substances and are UV stabllised.

These fittings are compatible with PELD, PEHD, PE40, PE80 and PE100 pipes, and may also be known as compression reducing joiners, compression reducing couplings, compression reducing couplers or compression reducing pipe joiners.

Click here to see how easy reducing sets are to install


Install PLASSON 1/2” – 2” Rural Fittings in four easy steps:

Ensure the surface of the pipe being inserted is free of scratches and other imperfections

Ensure both the end of the pipe and the fitting itself are clean of sand, mud, stones, etc

Do not over tighten the nut – this can spread the nut cone and result in pull outs

When fittings are reused it is crucial to replace the grip ring to avoid pipe blow outs.

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PLASSON Poly-to-Copper compression fittings are specially designed to connect new polyethylene pipe to traditional copper pipe work

These fittings have a copper nut at one end and a black nut at the other.  The copper nut connects to the copper pipe and the black nut to the polyethylene pipe.‍

How to install Poly-to-Copper fittings:

  • Prepare the pipe ends – cut straight, chamfer and lubricate
  • ‍Release copper nut half a turn‍
  • Place a witness mark 6 cms from deburred pipe end on 15mm (1/2”) and 7cms on 20mm (3/4”) copper tube‍
  • Insert lightly lubricated copper pipe until the witness mark on the pipe reaches the end of the nut‍
  • Firmly hand tighten and then a further ¾ turn using spanner or similar‍
  • Repeat process with black nut inserting into polyethylene pipe

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Wondering how to join pieces of pipe of different sizes?   PLASSON make it simple.  Reducing sets and reducing fittings are the quick and reliable way to connect different diameter HDPE pipe.

Compression reducer fittings match common pipe sizes and are usually PN16 rated. Reducer compression fittings are made from PE100 and are precision molded to they are light yet tough.

Using a compression reducing tee off a metric HDPE pipe provides a smaller size outlet to the main pipe
Compression reducing tees are often used to supply water or other fluids from a main pipeline
The smaller off-take will have less flow than the original pipeline

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Poly pipe joiners are easy to use and learning how to install leak-free poly pipe joiners is also easy too:

Incorrect installation
When pushing fittings onto the pipe, ensure the pipe is inserted fully. If the fitting is only partially inserted onto the pipe it will not create a watertight seal. When the pipe is traveling through the fitting there will be some resistance. This means you can think the pipe has been pushed all the way into the fitting.   Making a witness mark will help show how far the pipe needs to be inserted in order to reach half way into the fitting.

Pipe issues

In order to seal tightly inside the fitting, pipe ends need a clean, straight cut. If the end is jagged or uneven, it will not create a watertight seal

If the tubing is cut on an angle, it is unlikely to seal and could also nick the O-ring

One way to avoid these issues is to cut pipe with a pipe cutter rather than a blade or saw

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