Welcome to the Solutions page Many people ask for assistance in the understanding of theoretical and practical aspects of the industry. I will endeavour to enlighten Douglas asks, Grant, Going into some of the suppliers we have run into a type of plastic tube that is being sold as refrigerant piping. This is interesting but will it work? Thanks for all your info. Hi Douglas. I have looked into what is being sold and the most common one is a polyethylene flexible multi layered tube. So let us have a look at this. The pricing seems to be very good as far as the tubing itself goes. The fittings and tooling are expensive but the entire package does compare well with copper and even aluminum. But why would one look at using this type of tubing as an alternative? Well, two positives spring to mind, the first one being theft. I have come across and heard many stories about copper tubing being stolen. In some instances pulled right out of plaster. You can complete an installation today and come back tomorrow to find all the pipework stolen. The other obvious advantage lies in the fact that this type of tubing comes in one hundred meter lengths. This could relate to fewer joints and therefore fewer leaks. Let us have a closer look at polyethylene flexible multi layered tubing. Polyethylene flexible multi layered tubing This system is designed to replace copper pipe in unitary HVAC installations. The tubing is available with or without insulation as can be seen in the diagram above. Construction Inner and Outer layers: PERT (Polyethylene of raised temperature resistance) Mid layer: High quality aluminum longitudinally joined using an ultrasonic overlapping welding technique. All layers are permanently bonded with a special melt adhesive and are extruded in one step to ensure a solid and strong construction. The following are advantages listed by the manufacturer: Strong construction
Can bend up to 90 degrees Can be installed in a continuous length Lower Labour cost Eliminates theft Direct burial Flexible and keeps its memory 100% oxygen barrier Mildew resistant 25-year warranty 50-year lifespan Detectable with metal detector Fitting designed to swivel after installation Elbow fittings almost eliminated because pipe can bend as normally required Lightweight Supplied in coils Technical Specifications from supplier HVAC Connections And Fittings There is a full range of pressurised fittings designed for the HVAC market manufactured from brass and copper. I was on the lookout for sizes available for a typical unitary installation and found the available range to be good.
Typical Fittings Parts of fittings 1. Stainless steel sleeve 2. Polyethylene collar 3. O rings 3 4. Fitting body Parts of fittings Tooling Some skill is required for the tooling but is comparable to the difficulty level of flaring, swaging and brazing (with penetration). 1. Pipe cutter 2. Pipe reamer (straightens pipe end, expands pipe for fitting and reams pipe end) 3. Crimping tool (interchangeable heads are required for each pipe size)
Tools used to connect the Polyethylene Pipe to the press fittings In addition external spring type pipe benders can be used. Douglas let us now look into the installation procedure starting with the basic tools. Pipe cutting As with copper, do not use a hacksaw to cut refrigeration piping. Cutting the tubing is simple using the tube cutter. Using tube cutter The cut tube should have no chipping or excess material on the inside or outside of the pipe. Reaming the Pipe The reaming tool is placed into the pipe Push reamer into pipe, turn to cut chamfers both on the inside and outside of pipe. At the same time the pipe is expanded to accept the fitting and the end is straightened out. Remove tool and examine.
Using reaming tool Douglas this is about it for this issue, next issue I will complete this with the crimping and installation of the tubing. Thank you for all your questions. Send your problems (and sometimes your creative solutions) to acra@netactive.co.za with Solutions Page in the subject line. You may include pictures. References: Quick Pro Pipes ACRA Thanks to Quick Pro Pipes for the permission to use their diagrams and information.