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Taps for basin type prototype 2

November 24, 2019 — BarryK

Yesterday I commenced construction of the solar water still simple-basin type, prototype #2, cutting the wood frame:

An important requirement when using the basin-type, is that the water must not be allowed to dry out inside the still. If dry patches occur on the black silicone surface, salts will be deposited that will be baked on and extremely difficult to remove. It is possible that those deposits will not be black, hence the efficiency of the still will be reduced.

Also, when the water evaporates, salts are left behind, and the water becomes progressively less opaque, again reducing the efficiency.

To solve the latter problem, water should be allowed to run through the basin, to flush out the sediments and accumulated murkiness in the water. To achieve this, the still must have a drainage tap.

I don't want a big tap sticking out the side of the still, want something that is almost flush with the outside of the wood frame. I do have something suitable...

Several months ago, I purchased four 20 litre collapsible water containers from Bunnings. These were a discontinued item, and the sale price was only $2.99 (if I recall correctly). I bought four, but after filling one with water, realised that I don't want to lug 20 litres -- my back was complaining. I have been using one for solar water distiller tests, so at least one was getting used, but I don't want them for camping.

The brand is Marquee, there is no mention of UV resistance on the package, so they probably aren't:


I notice that BCF have an identical-looking one for AU$19.99

Anyway, they have dinky little taps, that I realised could be used on the distiller. Due to probably lack of UV resistance, would have to shade them. Here is the tap disassembled:


I want two of these taps, to go at diagonal opposite sides of the basin. Yes, a tap on the inlet side also, which will serve to stop hot air escaping. The tap on the inlet side will face up, and I plan to use a funnel to put in precise amounts of water.

I purchased Holman 13mm end caps, from the trickle pipe fittings section in Bunnings, and cut the end off, which gives a convenient flat surface. Then used glue to stick it on:


...a hole will be drilled in the wood frame, through which the 13mm barbed-joiner will be inserted, and the holes are for screwing the tap to the frame. Very simple, and extreme light weight.

I have mentioned the glue before. It is Selleys All Plastic Fix, which will glue any plastic:

Changing the subject, back onto the wood frame. As I have hardly any wood working tools, only a table and a few hand tools, I have had a problem with holding corners in place when I screw them together -- there is the risk of slight movement. This time, I am attempting to hold the corners in place with a bit of silicone in each corner:

imgx this photo, the frame is resting upside down on the glass. Hopefully, once the silicone has set, I should be able to drill and screw without movement. 

A couple of extra points related to this post.

Firstly, the 140x12mm pine. Bunnings only stocks it in 2400mm and 1200mm lengths. Unfortunately, for my 672x572mm glass, the total length of timber required is a bit over 2.4 metres. If someone was to copy this design, slightly narrower glass, to reduce the total wood length under 2400mm would make the wood purchase more economical.

Secondly, I am aware that the plastic used for those taps is probably the cheapest type, with very low temperature limit. PVC, without any additives, will soften above 60 degrees C. There is one YouTube video, where the chap used PVC pipe for the water runoff inside the basin still, and it sagged.

In my case, the taps will be outside the still, and in the shade. The water pipe to the taps will be designed in such a manner that the hot water or air does not directly reach the taps. Will discuss this some more when construction gets to that phase. 

Tags: nomad