Contrary to what the forecasters said it’s been a great day here at the north end of Raasay, though my initial thoughts as I lay in bed seemed to agree with them. For at 6:30 the rain was pelting down, the wind howling and I did not feel like stirring from my warm dry bed. Still the pigs needed feeding, the bins taking to the end of the road and the hydro pipe sorting so I reluctantly moved.
If nothing else I could at least get the quads power washed and the four new tyres fitted to my mates Yamaha. No sooner had I done the 50 yard dash to my oilskins in the workshop when the sky lightened, the rain eased and I worked my way around the herd with a jaunty ease.
The house and its occupants were still at slumber so I took advantage of the oilskins and started to give the quads, or at least two of them a good power washing. My mates Quadzilla because he was due up and I’d dragged it out of his shed yesterday to give it a run and pump up the tyres. Nothing worse than arriving on holiday to fine your transport with flat tyres and battery 😦
The Yamaha was needing a set of tyres fitting and the job would be much easier once I’d removed several kilos of Scotland from it’s undercarriage 🙂 Not only that but the sound of the Honda petrol power washer screaming away at the back of the house might wake up the yoofs 🙂
Sure enough it did the trick and pretty soon I had my team out working in the pits 🙂 A simple job if you’ve got a tyre ‘bead breaker’, air compressor and tyre levers but I have none 🙂 Still I am good at improvising and after driving over the wheels with the Land Rover we soon had the tyres off the bead. A screw driver and crowbar had them off the rim, a hammer had the new tyres back on.
Then it was a ratchet strap around the tyre to seal it and a diving cylinder to blow it up 🙂 Sounds easy but it took us the best part of the morning.
Though that did include two breakfasts and a new set of front brake pads 🙂
Changing Yamaha 350 Bruin brake pads
The front disc brake pads on this are very simple to change, just loosen the two 12mm bolts that hold the calliper onto hub carrier. Once the bolts are out you can ease the calliper forward enough to jam a flat screwdriver between them and twist it. This will help you remove the calliper over the disc, the pads are held in by two long allen bolts that need undoing and there is a shim on the pad that adjoins the piston. This ‘anti squeal’ shim has an arrow punched in it which does NOT mean up, it does in fact mean ‘direction of rotation’ so should be fitted pointing down the way. Give the whole assembly a good cleaning and squirt of WD40 to remove any cr4p from around the piston. The piston can then be pushed back with a G clamp till it is fully home, then assemble the pads into the calliper with some copper grease on the BACK of the pads, shim and allen bolts. Secure the calliper back onto the hub carrier then pump the pads back out with the brake lever, job done 🙂 Well apart from re fitting the wheel and doing the other side 🙂
That done it was time to give the tyres a good testing over the boggy moor to see how the hydro penstock was doing. All was good at the outlet at Tarbert with no sign of any air so we walked the length of the pipe drilling wee holes at the high spots to let out any trapped air.
Or should I say the boys pal who was wearing a one piece waterproof suit drilled the holes whilst we stood back 🙂
The first four or five had no sign of any air in the line,
neither did the larger ball valves that I’d fitted yesterday.
The last three however that were closest to the loch and under the least pressure did have tiny amounts in them. So I left the one closest to the inlet open after the other two had cleared figuring that air would escape there before it got further up the line. Perhaps a larger self bleeding valve is required here?
Once back at the loch I fitted the vacuum gauge to the only part under negative pressure.
7.5 inches of mercury it read with the pipe running at 3lts/sec which I suppose means that the height of the siphon is something less than 2.3m. Each inch of mercury equals around one foot of head (I think) so around 2.3m, but that’s with the siphon running, I presume it’s static reading would be lower?
Anyway, we could hear what sound like air in the pipe here so it needs a little investigation. It’s either leaking in via the valves for priming or coming out of suspension. The valves I can (with a little work) submerge in the loch and if it’s coming out of suspension I have a cunning plan.
Or at least Damian from http://fieldlines.com/board/index.php/topic,145889.0.html and Hugh from http://scoraigwind.com/ came up with a possible solution.
What I came up with for that was a chamber located above the pipe at the high point of the siphon. A valve below the chamber separated the chamber from the top of the pipe and another valve at the top of the chamber connected the chamber to the atmosphere. To operate: shut the valve to the pipe, open the top valve and pour the chamber full of water, shut the top valve and open the valve to the pipe. The air in the pipe escapes into the chamber and the siphon is maintained. Come back in a week (in that case) and refill the chamber with water. Of course the bigger the chamber the less often you have to refill. I’m sure you could automate it or find another way to skin the cat. For example, if the negative pressure is not too high or the rate of accumulation of air too great, make the top valve a check valve, connect a small vacuum pump to the outlet side of the check valve and turn it on and off with a float in the chamber. A small solar panel and a battery could power this, or you could power it with muscle power. As far as I can see, you are onto it, it’s just that, whether you are carrying water or pumping air out under negative pressure, I think you will be supplying a bit of energy to the system at the high points of the siphons to keep it running.
Hope this helps,
Basically a pressure vessel between valves D and E and I’m thinking that an old (none Balmoral) heating oil tank may do the trick 🙂
Another faulty Balmoral oil tank
I’ve lost count of the number of faulty Balmoral heating oil tanks that I’ve acquired over the years but it must be just about everyone on Raasay. At least half a dozen of these rotationally moulded tanks have come my way over the years and been turned into housing for piglets. However I was needing something a little larger for two full grown sows that need moving onto fresh ground.
Jamie Lea and Bramble are moving up to our new house site to help clear the ground for the new barn and house so they need some pre fabricated housing as we’ve not got a road up there yet 🙂
I may not be the sharpest tool in the box but I do have a knack of ‘proper recycling’ 🙂
Take one faulty oil tank that’s been floating in the sea and washed up on Raasay, cut it in half,
stick a pallet on the roof,
cover in corrugated iron
and you’re almost there 🙂
You’ll have to tune in tomorrow to see the finished product as we had to take it up the hill in sections and have yet to finish it 🙂