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Dr Bob

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Dr Bob last won the day on February 14

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About Dr Bob

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  1. Plastics in the cut

    Surprisingly, one of the biggest uses of recycled polypropylene is in making car panels ie a large number of the internal panels you get whey you buy a new car, - the dash board, the door internal panels, the floor pans, the parcel shelves etc etc are all polyprop, often covered with a nice covering. All of it is black and if it wasnt used, the manufacturers would have to buy new virgin plastic which means millions of tonnes more of CO2 emitted. The panel manufacturers are crying out for 96-98% purity recycle PP and would use far far more than they do now if it was available. There is a lot going on in the recycle arena that the public just dont see. There are reasons of why something is done one way or done another that the public dont understand so it is difficult for most people to get there heads around what they see. The bottom line for me is that now the route of waste to china is no longer available (they had cheap labour to separate by hand), we must do the separation ourselves (with new technology) but more importantly lets make products that minimise the separation needed.....hence I agree with your taxation view.
  2. Plastics in the cut

    The problem with black plastic is that the technique to separate you are talking about is Near Infra Red analysis (NIR). The NIR machine can tell plastics apart as long as they are not black. Black absorbs all the NIR signal. So the NIR sorters work ok with any colour as long as its not black. However, the NIR sorters are not really that good. You can get maybe 90% purity if you are lucky which in many cases is not high enough purity. An example is separating polypropylene from polyethylene. You really need 95% purity if you are going to replace virgin plastic. Assuming it is not black then, an NIR sorter is not really going to provide that purity - and the polymer then gets sold off for a 'lesser' application at a lower price. There is new technology now appearing that can get to 95%+ purity on PP/PE (and it works on black polymers) which should be fully commercial soon. The problem with banning black polymers is that many recycled items are made black to give a consistent appearance - ie the recycled polymer is 'jazz' - a term used for mixed plastic chips. If you banned black, then it would limit the recycle opportunities.
  3. Six Nations

    The back row is our weak link. Apart from Billy I think we are short two really world class back rowers. Lets hope some of the youngsters step up ahead of the world cup. Shame the two Irish wing forwards are not English!
  4. Plastics in the cut

    Agreed, and focus that tax on items where the 'source' makes it difficult or impossible to recycle. I keep banging on here about the 'sources' mixing the plastics which is a big contribution to not being able to recycle them ie PET bottles/tops. Coffee cups are another example of making an item out of something that is very difficult to recycle. Coextruded plastic trays containing barrier polymers with linear low density film (cling film) over the top. All items that use plastic packaging should be designed so there is a clear route to recycle otherwise slap a big tax on them.
  5. No Forum

    If you hit the view new content tab, you can see all the recent posts to the forum. At the moment it is not showing any posts between 4 hrs and 13 hrs ....ie the site not working properly. It must have come on around 5 ish when Irob posted replies to 5 threads. I tried to access the site last night but as Daniel said, all you could see were the basic page lines and although I tried to post, it wouldnt let me. Using simple maths it looks like it went off around 8 ish last night. Again well done to Richard.
  6. Battery Monitor Shunt Wiring Best Practise

    The way I have always done it is to connect the shunt to the negative of the batteries and then the bus bar so as you say you dont capture stuff from the MPPT to the 12V...but as buscuits says...does it matter. What is the shunt for? It is to help the battery monitor monitor the batteries. Therefore it is only interested in what goes in or what goes out - which is what you measure with the shunt on the negative. Ok, it doesnt line up with your power audit as less goes in and less goes out if you have an MPPT or are connected to shore line (and inverter), but you live with that. In practice I look at amp hrs used overnight, ie actually what comes out of the batteries. I am not really that interested in what comes out of solar in the day to run a pump without it going into the batteries. edit. therefore I wouldnt wire it up as per your diagram
  7. No Forum

    Jeez, no Forum for 9 hours. I had to watch Dancing on ice instead. Well done to the clever person who sorted it.
  8. End of winter?

    Patient: Doctor Doctor, I've broken my arm in two places Doctor: Well dont go there again spoiler alert....... there's thousands of them http://www.euphoria.force9.co.uk/realhumour/jokes/jokedrdr.html
  9. Six Nations

    Fully agree. I think he is still Englands best 7 at the moment so not sure how Wasps can see him as surplus to requirements given all the injuries the teams are now having. Like to see him in the starting 15 agains the Scots.
  10. Height of a narrowboat

    or even a flying boat
  11. End of winter?

    Patient: Doctor Doctor, I keep having this dream of sliding back and fowards Doctor: Mr Wilson, will you get out of the filing cabinet.
  12. Aceleron - repurposed lithium batteries for boaters

    Lets assume they are just plug and play - without any worries of charging or fire or sub zero etc etc £3000 for a 300Ahr which replaces a 500Ahr lead acid bank so £450 a pop to replace. If lead acids last 2 years as MrSmelly said then the Lithiums have to last 20 years (taking into account the cost of capital - ie up front cost for those not into NPV''s). Their benefit is that you will be able to get your overnight useage back in from 2 hours of engine running. The big big negative is that battery technology will move forward at a pace and in the next 5 years there should be a cheaper alternative to the £3000 on offer today. Buy lithiums today and you are locked in for 20 years. The summer is no problem for power and if a live aboard is in a marina for most/all winter on shore power then lithiums are not there yet. For an off grid CC'er, then the fast charge in the winter may be the stimulus to splash the cash now. Lets now assume they are not plug and play....................er, no chance today.
  13. Six Nations

    Naw, tomorrows game at the Ricoh is the big one. Time for Exeter to loose.
  14. Height of a narrowboat

    There is a major problem in trying to adjust the boats airdraft via adding/subtracting ballast and that is you have to lug the weight round with you ....so then it is not adjustable. Far better is to adjust the airdraft by changing the density of the water you crusing on. If you therefore hit a shallow bit of canal, you turn on the salter machine which pumps water into jets on the bottom of the boat, but that water goes through cassettes of salt thus creating a salt water layer under the boat. Salt water is denser than canal water so the boat floats higher. To go under a low bridge or tunnel, instead of circulating the water through the salt cassette to the bottom of the boat mounted jets, you inject air into the water (or even methane if you have a couple of cows on deck) so the water under the boat is now saturated with minute air bubbles thus creating a layer of water with a density less than canal water. The boat therefore sits lower in the water. Air draft can therefore be controlled quite accurately giving about 9.5 inches of variation in air draft. Quite a few boats are using this technology now.
  15. Height of a narrowboat

    No, sounds more like Latvia.