UK: Revised guidance on the selection of copper tube and fittings for use in refrigeration and air conditioning systems has been agreed by two leading industry bodies.
The Institute of Refrigeration and British Refrigeration Association have collaborated on the important update, following a proposed change in the European Standard EN14276.
Gordon Adams, technical manager at Climate Center, who played a key role in the revision, says: "The result is an increase in the maximum allowable pressure (PS) for equivalent thicknesses of copper tube, which will create a level playing field for the industry across Europe.
"The revised guidance incorporates new design stress values for copper tube, which were not included in the original European Standard. A recent amendment, however, has proposed that stress values be included in a future review of the Standard, opening the way for a review here in the UK.”
Following some detailed development work and discussion by relevant industry committees, it has been agreed that this new approach can now be applied in the UK.
The changes, which have taken two years to implement, have implications for a number of key standards and practices used in the UK refrigeration and air conditioning industry.
For example, the strength pressure test required on copper tube under the Safety Standard BS EN378 has been clarified, and now allows - subject to certain conditions being met - for the test to be carried out at 1.1 times the maximum allowable pressure.
The main change from the existing BS1306 standard to the European Standard EN14276 is a reduction in the safety factor, allowing the use of increased pressures for tube with the same wall thickness.
Gordon Adams says: "It had been recognised for some time that the British Standard was very conservative. The revised guidance gives more latitude, allowing a stress value at 150deg C to be used for discharge lines."
The new guidance gives clear tables for the maximum allowable pressure of copper tube for the common diameters and wall thicknesses. It also highlights the minimum design pressures for commonly used refrigerants, bringing key information into a single reference point.
Gordon Adams says: "Given the importance of the guidance for the safety and reliability of plant, we have gone through the data underlying the proposed changes extremely thoroughly. The key thing was to get it right, and ensure the industry could proceed to use the new approach with confidence."
He added: "I would like to thank my colleagues from both the IOR and BRA, who have worked closely to evaluate and agree the changes."
The guidance, "Selecting copper tube and fittings", Institute of Refrigeration Guidance Note 25, is available to download here