PE Pneumatic Flow

Vinidex PE pipe systems are ideal for the transmission of gases both in the high and low pressure range.

The use of compressible liquids in PE pipes requires a number of specific design considerations as distinct from the techniques adopted in the calculation of discharge rates for fluids such as water.

In particular:

  • Compressed air may be at a higher temperature than the surrounding ambient air temperature, especially close to compressor line inlets, and the pressure rating of the PE pipes require temperature rerating accordingly. For air cooled compressors, the delivered compressed air temperature averages 15°C above the surrounding air temperature. For water cooled compressors, the delivered compressed air temperature averages 10°C above the cooling water temperature.
  • For underground applications where the PE pipes are exposed to ambient conditions, the surrounding air temperature may reach 30°C, and the pipe physical properties require adjustment accordingly.
  • High pressure lines must be mechanically protected from damage especially in exposed installations.
  • Valve closing speed must be reduced to prevent a build-up of pressure waves in the compressible gas flow.
  • Where gaseous fuels such as propane, natural gas, or mixtures are carried, the gas must be dry and free from liquid contamination which may cause stress cracking of the PE pipe walls.
  • Vinidex PE pipes should not be connected directly to compressor outlets or air receivers. A 21 metre length of metal pipe should be inserted between the air receiver and the start of the PE pipe to allow for cooling of the compressed air.
  • Dry gases, and gas/solids mixtures may generate static electrical charges and these may need to be dissipated to prevent the possibility of explosion. PE pipes will not conduct electrical charges and conducting inserts or plugs must be inserted into the pipe to complete an earthing circuit.
  • Compressed air must be dry, and filters installed in the pipeline to prevent condensation of lubricants which can lead to stress cracking in the PE pipe material.

Compressed Air Systems

Polyethylene pipes have many attributes which make them ideal for compressed air applications. More information about PE for compressed air applications can be found in an Industry Guideline PIPA POP002 – Polyethylene (PE) Pipes and Fittings for Compressed Air.

Compressed air systems contain substantial stored energy, which, if released suddenly, could cause injury. For this reason, a greater factor of safety is applied to compressed air systems than to liquid systems under the same pressure. It is also recommended that pipe system design, installation and maintenance be conducted by those with appropriate knowledge and experience. Care is needed to avoid unplanned overheating of the system.

Allowable pipe system working pressures

The following tables for PE 100 and PE 80B pipe systems are based on a safety factor of 2 and give maximum operating pressures in kPa. Under these conditions, system life is expected to exceed 50 years. However, for continuous operation at temperatures above 40°C or for variable temperatures contact Vinidex for advice:

PE 100 pipe Maximum Allowable Pressure (kPa)
Pipe Class SDR Operating Temperature
20°C 25°C 30°C 35°C 40°C
PN 10 17 625 568 568 521 521
PN 12.5 13.6 794 722 722 661 661
PN 16 11 1000 909 909 833 833
PN 20 9 1250 1136 1136 1042 1042
PN 25 7.4 1563 1420 1420 1302 1302
PE 80 pipe Maximum Allowable Pressure (kPa)
Pipe Class SDR Operating Temperature
20°C 25°C 30°C 35°C 40°C
PN 10 13.6 500 500 417 385 385
PN 12.5 11 635 635 529 488 488
PN 16 9 800 800 667 615 615
PN 20 7.4 1000 1000 833 769 769

Fuel Gas Systems

Polyethylene pipes are also ideal for fuel gas applications but must be designed and installed in accordance with AS/NZS 5601.1:2013 “Gas installations. Part 1: General installations” which includes limiting conditions for the location of PE fuel gas systems.

Gas Flow Tables

Gas flow tables are reproduced from AS/NZS 5601.1 and are to be read in conjunction with this Standard.  The sizing of piping for materials or conditions other than those in the pipe sizing tables should be determined using recognised systems or formulae.

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