PEX CARBON REMOVAL USING BBU OR POLY CLEAR HMEX OR BOTH

For our latest case study we spoke to Michael Knabe, our Distributor for Germany who has helped develop the best purging solutions for extrusion machines producing PEX (cross-linked polyethylene) pipes/tubes. PEX is a special case, polyethylene is one of the easiest and most stable polymers to process. But when you add a cross-linking agent it becomes one of the most difficult and unstable polymers of all to process. We initially looked at two types of die which shape the molten polymer whilst in the machines: torpedo/spider die, a very simple design made by Nokia Meiler, which you won’t be surprised to know, is torpedo-shaped and has locating legs that look like a spider… spiral flow die, which is a more complex design, can have up to 4 layers and you won’t be surprised to know, is spiral-shaped! Their torpedo dies are used to produce small single layer pipes of 32mm diameter, while their more complex multi-layer pipes are produced using their spiral flow dies. This process is known as extrusion and the pipes it produces with PEX are used for, among other things underground heating. We already know that Barrel Blitz Universal (BBU) contains a soft filler that doesn’t melt so it can’t go through dies with very small diameters ie 1mm or smaller. And many spiral-flow dies have small diameters, so this was one critical safety area that had to be investigated. Although gap clearance is important, Michael also had to do thorough testing and experimentation (well, that’s what he told us!) to arrive at 3 cleaning methods. This testing had to take several factors into account: how much cross linking and degradation has occurred in the equipment Poly Clear HMEX can remove colour, loose Carbon and deCarbonise, but won’t clean the machine as thoroughly as BBU BBU is very effective at removing Carbon in high compression areas, but can’t be used on small diameters So here are the 3 methods that Michael devised for different machines and different situations. CLEANING METHOD 1: 2.5KG BBU AND 2.5KG POLY CLEAR FOR TORPEDO DIES OR SPIRAL FLOW DIES OF 1MM+ This is most straight forward and cost effective cleaning method that can be used once a machine has started up and you can see carbon specks in the pipe. You don’t need to shut the machine down, you purge using 2.5kg of BBU and then check to see if the Carbon has been removed (the BBU should come out as white as it goes in). You then purge with Poly Clear HMEX to clear the BBU and any low compression areas in the equipment. Cleaning Methods 2 and 3 (below) are suitable for machines with dies of any size or type, but are particularly suitable for machines with spiral flow dies with a diameter of less than 1mm. CLEANING METHOD 2: A QUICK CLEAN AT START UP USING 8KG OF POLY CLEAR HMEX When you start your machine on Monday morning and you see Carbon specks, you can clear these out quickly using 8 kg of Poly HMEX. This should remove all of the loose Carbon and get you going. But not all the baked-on Carbon will be removed. If there is more Carbon present the following Monday, which is possible because the machine has cooled down over the weekend, then repeat this method or consider Cleaning Method 3 at the end of the week. CLEANING METHOD 3: A DEEP CLEAN ON SHUT DOWN USING 10KG OF POLY CLEAR For machines with complex dies that produce up to 4 layers (and are not suited to BBU) and to remove baked-on deposits, Michael recommends 10kg of Poly Clear HMEX to shut the machine down for a deep clean (also known as decarbonising) over the weekend. Poly Clear decarbonises in two ways; firstly, it has surfactants that seep in between the Carbon cracks and loosens the Carbon and secondly, Poly Clear has an additive that causes the Carbon to attach to itself so when the machine cools the Poly Clear shrinks and it shears the Carbon from the metal surfaces. Then all you need to do is use 8kg of Poly Clear at start up to remove the loosened Carbon. This is the most effective procedure for using Poly Clear to remove Carbon. Most companies use this preventative method for cleaning machines with the more complicated spiral flow dies as they find it keeps the carbon specks at bay for the longest period. If you’re not sure which technique is the most suitable for your machine(s) we recommend purging Poly Clear during a run, and if Carbon specks start to appear this shows that you have Carbon inside your machine. We would then suggest you try a deep clean with 10kg of Poly Clear. DO YOU KNOW YOUR CLEANING CYCLE? To carry out a deep clean that’s going to last for the longest period you need to decarbonise the machine at shut down first. Before doing this we ask our clients if they know how long it usually takes for Carbon to appear, say 4 or 6 weeks. If you aren’t sure how long your Carbon-free cycle is, Michael suggests purging with 8kg of Poly Clear at start up. This will eradicate any loosened carbon and should allow you to produce all week without any rejects. We can also work with you to calculate the most efficient cleaning cycle for each machine. And once that’s done you should be carbon-free for the life of the machines. DO YOU MANUALLY CLEAN YOUR MACHINES? GET IN TOUCH! Aquapurge’s cleaning materials mean the days of time-consuming manual cleans and late-in-the-day start-ups for your machines are over. Once you’ve worked out the time it takes before specks start appearing you’ll never need to manually clean again and your start-ups will be much swifter. If you’re not sure about the benefits we’re only a phone call or email away.

For more information on PEX CARBON REMOVAL USING BBU OR POLY CLEAR HMEX OR BOTH talk to Aquapurge Ltd