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RE: Water Purification Portable DIY prototype
Picture 1 shows the two original commercial units I sourced off ebay. The left hand one is the activated charcoal filter. When I managed to break the seal on the top and remove it - it was found to contain almost completely activated charcoal granules. Each end had a thin disk of spongy fibre material pushed in to stop the granules escaping from the filter in & outlets. For the ebay cost of £2.50 +p&P. there is enough activated carbon to make many personal filter systems or also to refresh my existing one.
The right hand filter element is a particulate filter. originally it was the same length as the charcoal one until I started cutting it up for the project. This is a simple hard foam cell tube with a filter size down to 0.1micron, so should be good for most contaminants.
Both these filters elements are originally intended to slot inside a housing that fits in a domestic dwelling in the pressurised water inlet supply.
Picture 4 shows the expedient charcoal cartridge housing for this project. It is actually a water overflow simple sprung pressure unit of some type, available on the shelf at the local plumbers. The internal rubber flap valve & spring assembly has been removes and in the picture it shows it with a short length of plastic pipe inserted & glued in the end of the outlet. Also you can see the black activated charcoal through the clear plastic body.
Picture 5 just shows some plastic tubing I sourced for this project. The one actually fitted to the filter unit is from my wine making siphon assembly inc the tap.
Picture 6 shows an earlier prototype that was not quite long enough for the black end cap to fit on. The components above are the individual new items before assembly with the correct solvent glue and the holes being drilled in the main body & deburred.
The bottom complete assembly is how it should look before the particulate filter is slid over the top. It was found it was too difficult to slide the foam filter over the black rubber endcap and this is part of the reason for the structural failure of this earlier prototype. The next time, I left the tube extending slightly longer & without holes in this part and after fitting then foam filter, then slipped the black rubber end cap on and glued it at the same time. it is important that no water may pass into the interior of the tube other than through the drilled holes via the foam filter.
Picture 6a shows me cutting down the diameter of the filter to improve the flow rate. it was found to be too slow with the full diameter in use.
picture 7 shows me retrofitting some UHU as an extra sealing precaution around the rubber washer/filter end. This is probably not necessary due to the tight tolerances of the fit.
You can see in pictures 7 & 8 the rubber seals/washers fitted at both ends of this foam filter assembly. they need to fit firmly against the inner tube and seal it as such.
Picture 9 shows a hole neatly cut in the bottom side of the water bag. this needs to be a firm fit around the plastic foam filter outlet pipe. this is fitted from the inside as shown in picture 10. The hole was cut by sharpening a short piece of copper pipe of the same size and hitting with a light mallet into the bag material witha softish wooden block underneath. After a few sharp taps the hole was more or less cut through. A tickle with a stanley knife eased the cut piece fully out.
In future I will cut the hole in the very bottom of the bag as it will hang & flow better. there is enough height at the base of the foam filter assembly to stop any larger particles from entering & clogging up the filter more quickly.
Picture 11 just shows another rubber seal/washer and a stock plastic nut that fit over the protruding outlet in the bag of the foam filter assembly.
Picture 12 shows the fitting of these.
Picture 13 shows PTFE tape being fitted to the end of the foam filter outlet - this creates a better seal on the threads that lock the foam filter and the carbon filter assemblies together. The seal at thsi point is on 3 different surfaces and so the PTFE is just "belt & braces".
Picture 14 shows the foam filter outlet ready for the charcoal filter to be connected up.
Picture 15 shows the Activated Charcoal filter cartridge with a short piece of pipe already fitted into the outlet & with the black activated carbon showing in the clear plastic body. the activated carbon must more or less fill this cartridge housing so that no water can run over the top of the carbon easily if the filter body is laid at an oblique angle whilst in use. Soft mesh is inserted in the inlet & outlet to stop the carbon escaping from the filter housing.
Picture 16 shows the Carbon filter housing being screwed onto the foam filter outlet pipe.
Pictre 17 shows the plastic tube that is mated up to the plastic outlet pipe by using difefereent sizes of plastic tube wrapped in Heat shrink tubing with a rubber grommet of the appropriate size fitted over the end. This rubber grommet with plastic tube inside is a firm push fit into the filter outlet. A simple on/off flow tap is fitted in the plastic tube.
Pictures 19 & 20 show the 2 different water bags I have chosen for the project. At the moment it is using the lighter weight webtex one but with the filter not fitted in quite the best place. next time it will exit the bottom of the bag directly. The black 17litre bag is much better quality, but it is heavier & more bulky. This I will retrofit to the filter and then I can use either.
I think the lighter weight webtex one is actually the more suitable choice for an individual wishiing to keep the weight down. The black on is more suited to a camp or if there is more than one person to distribute the load and would be more robust & longer lasting - it appears from initial inspection anyway.
Picture 21 shows the complete bag filter assembly but without water. I have yet to test the new flow rate.
Please xcuse spolling mistaks as I is gone bed long time soon...
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