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Ultra light camper trailers

November 26, 2019 — BarryK

Interested in these, for stowing extra gear when on a camping trip. There is a chap on Facebook, lives in Western Australia and owns a Suzuki Jimny 2019 model. As the engine is very small, 1.5 litres, and legal towing limit is only 1300kg, he bought a motorcycle trailer, the Erde 122:

img1 has a nice pod lid, and total weight is just 65kg. Ah, not at all clear from the webpage, but that 65kg is without the plastic lockable top. Found out the top weighs 21kg. This UK site shows there are lots of accessories:

They have another trailer, complete with tent and only 115kg:


Erde trailers are imported from France, so anyone in Europe should be able to acquire them.

Here is another trailer, the Asyon pod, that weighs 100kg (though, their front page states 130kg):


...sold in the Eastern States, from the description, look like local manufacture.

Very interesting! 

Tags: nomad

First go at using expanding foam

November 26, 2019 — BarryK

Well, that was a learning experience... aiming for extreme light weight, I had the idea of not using plywood for the floor of the basin, instead just the insulation itself. The problem though, is plywood would be required when applying the insulation, so as to get a flat surface, then afterward the plywood could be removed.

Expanding foam, that comes in pressure cans, is polyurethane, which is a thermosetting plastic, and can be expected to keep its integrity at the expected maximum temperature inside the solar still -- that is, won't sag.

I also found information that silicone sealant will stick to it. So I decided to go with this idea. The insulation is going to be 35mm thick (except toward the back, where it tapers to a bit less, as you will see in the photos). I have a piece of 12mm MDF, so cut that to fit snuggly inside the still. Needed some supports to hold the MDF:


I read on the Internet that expanding foam will not stick to baking paper, due to its wax coating, so I put that on the MDF, held in place with sticky tape, and inserted into the still frame:


OK, the idea seems simple enough, apply the expanding foam, let it set, then use a large saw to trim. I am a complete novice with expanding foam, so watched some YouTube videos first. I took the recommended precautions, face mask, latex gloves, and sprayed the surface lightly with water before application.

I bought a 500ml can of Sika Boom AP expanding foam, claimed coverage 25 litres. The area that I need to fill is about 0.6*0.7*0.035, which is 0.0147 metre-cubed. One litre is 0.001 metre-cubed, so that works out as 14.7 litres. That can should be more than enough...


...that is what it looked like after I arrived back from Bunnings with another can. The second can is 340ml Parfix, the cheapest and smallest.

Another spray of water, then finished it off. then waited until the next day. Cutting the foam was easy:

img4 will need to be planed a bit more even.

Now for the other side, which will become the floor of the basin. I pulled off the MDF, and found that the surface is not flat, it has waves:


The waves are up to 5mm deep, not acceptable. I think that what has happened is that as the foam expanded, it lifted from the base. It was not stuck to the base, due to the baking paper.

I read about using baking paper on the Internet, but no one said anything about this. I could spread something over it, to make it even, however, I have gone off this technique.

I will give it some more thought, but I think that I will pull the foam out, and instead install a thin plywood floor with some structural support, then apply the foam -- it should stick to the wood and not lift off.

Or, I could use fibreglass batts. But, grumble, I would then have to buy an entire pack of 9 batts, cheapest at Bunnings is AU$37.45. Weigh that against 850ml Sika Boom expanding foam, at AU$18.96. I might let this rest for awhile, feel that I have given Bunnings enough money recently! 

After reflecting on the situation and an afternoon snooze, I decided to keep the foam fill as it is, and fill the waves. I have lots of partly-used acrylic sealant tubes in the garage, plus a couple of full tubes, so this looks like the best choice to fill the dips in the basin surface.

Most acrylic sealants have a "service temperature" of 80 degrees C, and there are some fire-rated ones up to 90 degrees C. For example, Sikaseal Joint & gap, Sika Caulk, and Full Caulk In Colours are all rated at 80 degrees. One exception I found is Sikacryl 100, interior use only, rated at 70 degrees.

Using the wide spreader, I have applied the first layer. It will need at least two layers I think, partly because acrylic sealant shrinks as it sets.  First layer was less than half of a tube, so the situation isn't so bad.

Of course, this workaround is not suitable for the final DIY plans. When I do finally get to publishing such plans, will probably specify a plywood floor for the basin.  

EDIT 2019-11-28:
I receive emails in response to blog posts, don't normally forward them to a blog post, just the occasional one. Like this comment from Sage (Puppy Forum name):

Expanding foam: you'll pardon my sniggers - I've used this quite a lot for building works, including garages and garden sheds. It runs wild not always into intended interstices and seems to have a mind of its own. Voids abound. Ended up cutting off more than exuded! A crude, if cheap, solution best suited to builders and desperate householders.

Yes, it does indeed have a "mind of its own". I received advice from Rick, that it would have been better to have forced the foam to stay flat by using 3mm plywood on the basin floor and back of the distiller, and injecting the foam into the cavity. 

Tags: nomad

Plastic taps for hot water from eBay

November 24, 2019 — BarryK

I posted this morning about taps that I got off collapsible water bottles and modified:

I will use these, but will make sure in the construction that I can substitute a different tap if required. I did a search on eBay, looking for plastic taps that are designed for high temperatures. I do have a requirement of compactness, however with a plastic tap there is the possibility of modifying it, and I am looking to see if the tap will be amenable to surgery.

Most of them do not specify type of plastic, nor temperature limit. However, a few do. This one is a 4-pack, AU$16.08 including postage, specified for long-term use at 95 degrees C and short-term up to 120 degrees C:


This one is 2-pack at AU$13.19 plus AU$6.15 postage, also rated for 95 degrees continuous use:


This one is AU stock, AU$7.50 each, AU$9.00 postage. Doesn't specify a temperature, however is made with polypropylene, which is good to 100 degrees C, and melts above 130 degrees C:


I will mention these, but they are probably cheap low-temperature plastic:

This is the same design as the taps I am currently using:

img5 could be sawed off and modified as I have done.

This is the cheapest:

And a couple more cheapies:

Just a few more, that are interesting:

There you go, lots to choose from! 

Tags: nomad

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

More planning basin type prototype 2

November 23, 2019 — BarryK

I posted recently about basin-type prototype #1. There is a link to testing it here, and notes about white colour for side walls in proposed prototype #2:

I have got to the point of starting construction of prototype #2. In planning, I found this document to be extremely useful:

I posted recently about the Rainmaker 550 basin-type, which claims 60% efficiency. This is the absolute efficiency, of how much of the sun's energy is actually converted to produce the distilled water (this is different from some earlier % figures that I posted, that were relative to the F-Cubed panel).

However, the above link states that the best that can be achieved with a simple basin-type is 43%. Hmmm.

For comparison, the F-Cubed company claim 55% efficiency for their Carocell 1000 (the one that I own).

EDIT 2019-11-24:
The C1000 model is 1x1 metres, but F-Cubed also sell C2000 and C3000, that are the same width, just longer. This gives a longer path for the rotating air, and they claim the bigger ones are more efficient, claimed 65%, with "peak efficiency" up to 80% (whatever that means).

Given how much simpler the basin-type is to build and use, this is now my focus for future prototypes. So what if it is less efficient? -- just build it a bit bigger.

Today I had a chat on the phone with Jim, a retired gentleman who also lives in Perth, and also has an ongoing interest in solar water stills. Many years ago, he built a simple basin type made with stainless steel, and a hinged glass lid for easy access to clean the inside.

Jim is interested in the F-Cubed design, but is put off by all the exotic materials in it, plastic everywhere. After chatting with me, he is also thinking of making his next build a basin type, or some enhanced variant.

As I have mentioned a few times, I want to be able to slide the still vertically into the back of my car, or future car. The basin type has considerable depth, and that is going to take up a lot of space if the still is to be packed in the car along with a lot of camping gear.

Hence, I am going for a very low angle, 10 degrees from horizontal. The link above, explains that sunlight gets reflected off the panel as it moves away from perpendicular to the glass. This is a good page that shows the angle of the sun in Perth, Western Australia:

...what it says is that if 90 degrees is straight up, the sun will be 81 degrees at midday in mid-summer, and will be 34 degrees from horizontal at midday in mid-winter.

This is telling me that my 10 degree panel should be OK in summer, but will be at best 56 degrees off of perpendicular to the glass in mid-winter -- which is not good.

What I am proposing is a hinged reflective panel, that will be raised in winter. This is hinged along the top side of the panel, and even in summer should provide some efficiency improvement. It will also provide protection to the glass when the panel is transported.

OK, starting the build. I bought 140x12mm dressed pine from Bunnings. This is very thin, but one of the goals of this prototype is to make the weight as low as possible. I am re-using a piece of glass that was used in the sloping-type prototype #2, 672x572mm, 4mm thick. A sketch of the wood pieces:


For an angle of 10 degrees, the back side of the panel should be 162mm, but I have used 140mm wide pine. Hence the 124mm indent that you see in the above sketch.

The two triangles that I have cut off the side pieces, could be used to make the back 162mm, if I wish.

The plan is for 30mm thick insulation in the base of the basin, and I am investigating using a spray can of expanding foam. But that is a story for the future... 

Tags: nomad

White walls inside basin type solar still

November 22, 2019 — BarryK

The first prototype solar water still, simple basin type, was tested recently:

And the inside was coated with black silicone (except for some grey patching, and the photo below also shows some reflected clouds):


What has nagged at me though, is why are the side walls coated black? Because that is the way it is done in all the designs that I have seen so far!

This morning, I typed some appropriate keywords into Google search engine, to see if there are any arguments for a different colour, such as white, or even a reflective surface. Got hits!

OK, it seems that the rationale for painting the side walls black is to prevent condensation on the walls.

However, that also means the walls will absorb heat, and will need to be extremely well insulated. In my prototype, they are not.

I found a couple of research papers, where the authors painted the sides white, down to the water level:

...the second author is claiming an efficiency improvement of 6.8% when the side walls are coated white.

There are a lot of variables in this analysis, but I reckon that I will go for white walls in prototype #2. 

Tags: nomad

Silicone sealants for potable water

November 21, 2019 — BarryK

I have posted before about silicone sealants that are suitable for use in construction of the solar water distiller.

I have previously used Selleys 401, translucent, purchased from Bunnings, AU$19.63 for a 310g tube:

...rather expensive.

Besides, I am now wanting black sealant, and Bunnings only sell the Selleys 401 in translucent. Also, I am now favouring neutral-cure for applications other than glass.

I recently discovered Bostik Industrial Grade silicone, at the Total Tools website, for AU$6.95 per tube -- except that no stores anywhere in Australia actually stock it, and it is a "special order" with high postal charge. Anyway, here is the manufacturer's specs page:

...Bostik is an international company, and in many places, such as the USA, you could probably pick it up from your local hardware store.

The Fuller company, also international, do a "plumbers silicone", rated for potable water use, but not available in black.

About a week ago, I discovered Silastic 732, acetic-cure, available in black and white, and stocked at Autobarn, a car parts and accessories chain store in Australia. This is also rated for use in potable water. Price is AU$18.99 per tube:

...I bought two tubes.

There was something nagging at my memory though, another brand, locally available. Yes, found it: Prosil 10, neutral-cure, available in various colours including black. And cheap, AU$8.95:


Here is the manufacturer's page: 

There was another that I discovered some time ago... German company... forget the name, but they only sell to the trade here in Australia, No retail outlets, not even online ordering. I did phone them, and they gave me the number of a salesman. That's their marketing model, sales reps who go to tradie sites ...not interested. 

Tags: nomad

First coating silicone on aluminium mesh

November 20, 2019 — BarryK

I posted recently about the idea of using an inner liner for the basin-type solar still, constructed with aluminium insect-screen mesh and coated with silicone sealant:

The mesh is not raw aluminium, it has some kind of dark coating, I presume that is an anodized surface. Don't know anything about the properties of that surface, but the silicone seems to stick to it OK.

Now for the next step, to coat a large piece of mesh. The intention is that this will be inserted inside the distiller frame, and will completely isolate the frame from moisture. There will also be some insulation injected between the inner liner and the frame. Still planning on using pine for the frame.

Want one large coated surface, which will be folded afterward, so a minimum of cutting -- basically, the only cuts will be for inlet and outlet holes, and to trim the edges where the liner is sandwiched under the glass -- anyway, those details will be clarified as the project progresses.

Here is a photo of the mesh stretched out on a table:


...the g-clamp has two purposes, to prevent the mesh from folding up when I lift it off the table, and to hang it up on a hook. The other end has a length of small-section wood attached with wire.

Underneath the mesh is plastic sheet. That plastic just arrived in my backyard one day, a year or so ago. Thought it might be useful, so put it in the garage -- so, finally it has a use!

Wanted an area about 950x750mm. Used cheap Parfix kitchen-and-bathroom acetic-cure silicone sealant from Bunnings -- this has anti-mold additive, which I don't want, but it shouldn't matter in the final product, as it will be coated inside with black Silastic 732 sealant.

The end result was hung up:


...the white spots and streaks are holes. I have learned from experience not to try and patch the holes. Instead, let it set and tomorrow will give a second coat. Note, that large white area at the bottom is direct sunlight. One more detail: I wiped the plastic with a cloth, to remove silicone bumps, as the plastic will be used again tomorrow.  

Tags: nomad