Isn't a Rotweiller tied to the Tank the best method?
|
Man trying to spend his pension lump sum.
What's wrong with the long broom handle method?
|
|
We ran out - of course it was my fault. Took a whole hour for the locally based oil chap to arrive. Of course SWMO missed several baths and there was a back log of pots to be washed, she doesn't do dishwashers so obviously neither do I. Just want to avoid it again.
|
We have a top up arrangement with our dealer. It doesn't cost anymore but if you always ring round to get the best price it may not be for you. But I guess if you always shop around you're unlikely to be the kind of person who runs out.
having run out over Christmas two years we aknowledged where we stood on that particular spectrum and went for the top-up.
|
|
We had a fuel guage on ours. Visible from the kitchen window. Therefore had it run out it would have been 'er fault. Simple.
|
|
Wouldn;t dare do that in my house. I am number 4 here.
|
|
|
|
Ours had an external clear pipe - simple and accurate, although I think you had to press a button at the lower end of the pipe to get a reading.
|
|
|
|
|
We use a local company (who've had to diversify from their long established coal delivery dependence ) he is cheaper than the large national company nearby. Totally reliable, I normally top up (never having run out before) it was our Christmas family crisis (or CFC) that threw our usual routine. Whilst talking about it, I also forgot to re-new my service contract with BOSCH-Worcester and the control unit went on boiler (375 quid plus call out and fitting) however when I phoned them, they backdated my contract and I didn't pay a penny other than a year's subscription. Brilliant service, they could have fleeced me.
|
|
How are prices now on heating oil? It's seven years since we had a house with that system and I want to say it was about £400 for a thousand litres then.
|
>>How are prices now on heating oil?<<
Like all energy prices - shocking
|
|
|
How are prices now on heating oil? It's seven years since we had a house with that system and I want to say it was about £400 for a thousand litres then.
In Dec 2007 we paid £498 for 1000 litres. In Dec 2004 it was £260. The price must have dropped between your last delivery 7 years ago and 2004.
|
|
It could of course be that I am mistaken. Perhaps I am thinking of yearly cost.
|
|
Mind you in chatting to the boiler tech, I told him that the system seemed to use less oil last year, he said it was due to the way he had set it up at the last service. :-o. I have to say Bosch Worcester have given excellent service in both hardware and back up terms. Only one call out in ten years (but guess I could have bought a new boiler if I hadn't have bothered with the contract)
|
last week it was 55.8 pence per litre.
there are a lot of pensioners who cant afford to buy heating oil at this price
|
|
|
|
|
|
|
Isn't a Rotweiller tied to the Tank the best method?
Sorry I got the basis of your question wrong. My comment followed a long news item this am about fuel thefts from outside tanks. Several of the people (sorry, victims of crime) were not aware of the loss until they ran out!
|
|
|
|
Talking about oil tanks reminds me of many many years ago when I was installing one.
I?m sure one of you clever guys will come up with the answer.
The tank we used was a steel cylinder about 500 gallons in capacity. It was simply a steel tank not primarily designed as a oil tank but we converted by welding in the necessary tappings.
It was placed horizontal on dwarf brick walls and piped up. No bother with bund walls at this time !.
The final task was a measuring rod which I fabricated from a solid brass one inch rod with a brazed on thread to screw into a tapping on the top of the horizontal tank.
Finally in the workshop we set out to calibrate the rod with filed marks and engraved numbers.
Well obviously halfway down would have been 250 gallons, but it was the rest of the numbers which gave us the mathematical problem.
We all got our bits of paper and calculators out and working in a prison establishment we had all the time in the world to play about.
No problem if the tank had been vertical but how do we calibrate it on the horizontal.
We looked in our reference books for a formula with no success.
Over to the Education Dept to ask the maths teacher and he didn?t know.
It didn?t really matter and we gave up after an hour or two and simply engraved it ?half? in the middle.
Now 40 years on perhaps one of you will come up with the formula. And please don?t tell me to ask the tanker driver to put in 100 gallons at a time and mark it as one or two suggested.
wemyss
|
It's a fairly trivial integral requiring no complicated integration, merely a little trigonometry.
See www.karlscalculus.org/calc12_2.html for a diagram - figure 12.2-2.
Remember, the area of OQC is (theta/2)/360 x the area of the circle, PIr^2.
This will give you the area of OQC in figure 12.2-2. And remember that as you're filling up the tank and the oil lies horizontally (or vertically in that picture) you need to add the area of the triangle formed between O, C and the point from where if you drop a vertical from C and a horizontal to the left from O. You'll need some simple trig to calculate that.
Then multiply by two to allow for the other side of the tank, and then try a few different angles and calculate the relevant volumes.
To solve analytically for 10%, 20% etc is a little trickier.
If that's all over your head, then I'm not sure I can explain using just text.
|
|
I think I'll buy the watchman. :-9
|
|
There was a feature on this morning's tv news about peoples oil tanks being siphoned. Apparently more common in rural areas, as the siphoner is less likely to be disturbed. The first thing most owners knew of it was when the heat stopped.
|
|
I was watcing that as well....I nearly chocked on my Kedgeree.
|
Rural crime - I've known five bar gates go walkies.
You would need a good sized trailer given their width and weight.
Agricultural tractors were easy pickings too, most only had a 'pattern' key whch could easily be replaced by a small screwdriver.
That fired up the glowplugs, push button/lever start and away.
Edited by ifithelps on 14/04/2008 at 19:52
|
|
|
|
Here's the sum
Volume = L r^2 ( arccos (1-(H over r) ) - (1-(H over r) ) * sin (arccos (1-(H over r)) ) )
L is the length of the tank
r is the radius of the tank
H is the height of the oil from the bottom of the tank
arccos is the inverse of the cosine function
|
Thanks for your answers. I'm not surprised now that we couldn't come up with the answer.
wemyss
|
|
I bet I'm glad I asked I think.
Edited by Pugugly on 15/04/2008 at 00:01
|
|
|
|
The alternative solution,
Volume = L.r^2[2PI.T/360 + sinT.cosT]
L is the length of the tank
r is the radius
T is the angle between the mid horizontal of the tank and the edge of the tank where the oil laps
And volume is the volume by which the tank is more, or less, than half full.
|
>>The alternative solution,
Yes, I had something similar as an intermediate step, (as such, the equation is actually more of a re-phrasing than an alternative) but I didn't think anyone would be too keen on working with the angle, so, I eliminated it in favour of the height of the fluid.
|
|
|
|
|
Tank level versus volume
Calculus is the way to go for mathematicians but for a simple approximate way, I was going to suggest the end circle was divided into horizontal strips, one above the other. Knowing the strip length (see below) you can then calculate the tank volume for each strip area, starting with a first strip sitting on the half full diameter and then do it for the next one above that, etc. Depending on the accuracy you want you can use more or less strips.
Obviously the tank volume is the end area times the tank length. Also that the upper half shape is a mirror image of the lower half and so calculations can be done for just that. Even simpler, the upper right quadrant, is a mirror of the left upper quadrant. So calculations can be done for just that quadrant and then doubled to get it for the upper half.
You need the width of the strips as you go higher up. Get that for the quadrant and double it. That can be obtained using trig. For that you need the height the strip is at its center above the half full diameter.
Knowing that height and drawing a line from that height on the circumference across to the circle center (a radious) and using trig, it is easy to obtain the angle of that radial line above the horizontal, because sin of the angle = vertical height over radius length for that triangle. Then the cos of that angle times radius gives you the triangle base length (same as the strip length you want across the quadrant).
Successively adding up the volumes in the strips as you fill the tank, you can construct a graph of tank volume versus liquid height (use the height to the top of each strip, this time) for the area that is above half full. Emptying down from the half full level loses you the same amount per strip as is gained in going up from the half full.
|
|
Never mind I'll use the dipstick and tie the Springer to it.
|
Just tidy up, once you know how the cylinder volume varies with height from half-full upwards, you can calibrate a dipstick (put marks on it.) The mark spacings going up and down from the half full mark, are the same. Going up is more gallons (or litres), going down is less gallons.
Since writing it using sin and cos, I have realized the calculation of strip length can be much simplified, because you can use the fact that the square of the hypotenuse (the radius) is equal to the sum of the squares on the other two sides (the vertical and the horizontal of a right angle triangle). You know the radius, and you will know the vertical height to each of the strips. So take the square of the height from the square of the radius and then the square root of the answer, and that is the length across the quadrant. The length across the end of the tank is just twice that. So calculating the volume held within the strip is easy. Use height to center of each strip so as to, sort of, average out the none square ends of the strips due to the tank curvature.
Use a few or a lot of strips according to the accuracy you require. In the limit, when each strip height approaches zero, there is no calculation error and we are back to calculus and integration again.
Surely some mathematician amongst us can solve that integration equation and give us the formula for the way a circular tank volume varies going upwards from the bottom or from the half full?
|
Buzbee, I've posted the relevant equation a few posts up the thread.
If you wished to invert the equation, and obtain the height for a known volume, then, it's actually easier to use a slightly modified version of the equation i gave as part of an iterative scheme - typically, you can get to an error in parts per thousand in about 5 steps.
the modification is to remove the (L r^2) term at the front, and replace it with (1/pi), this then represents the volume fraction of the tank. The iterative scheme goes like this;
i) Decide which volume you want to mark
ii) Work out the desired volume fraction by dividing i) by the total capacity of the tank
iii) Evaluate the modified equation but with H/r = 2* the answer given in ii)
iv) Subtract the volume fraction obtained from that desired (this is the error)
v) Add half of the error obtained in iv) to the value of H/r
vi) Evaluate the modified equation but with H/r modified as per v)
repeat steps iv), v), and vi) until the error is small enough to be ignored.
Using the converged value for H/r, you can then multiply by the radius to obtain the required height of the mark.
Steps i), ii), and iii) are really just about choosing a suitable starting point for the iteration - you can just use 0 as the first value of H/r, but usually, this will mean you need to do a few more iterations before the error reduces to an acceptable number.
|
|
|
|
|
|
|
Had one for several years now - came with the new tank. Much easier than faffing about with a stepladder & an old broomhandle. Never had any problems with it.
|
|
|
|
