RicodJour wrote in news: snipped-for-privacy@d23g2000vbm.googlegroups.com:
Looks pretty slick. Probably worth a few hours of investment time to learn to use if you have repeated uses as Steve says he does. If it only takes a few hrs to learn a specific use that speeds thing up, the ROI would be great.
harry k wrote in news: snipped-for-privacy@f20g2000prn.googlegroups.com:
Well I pulled it outta my ass. What do you expect? Just because I can talk out of my ass doesn't mean I have an intelligent asshole.
bud-- wrote in news:76aeb$4ace0f5d$cde8d5b3$ snipped-for-privacy@DIALUPUSA.NET:
Good idea! Then to get rid of the oil you just toss in a hose and let it overfill till the oil is gone. Oh hell, even a forest flattened from fire comes back. The pond surroundings should come back...eventually.
Oren wrote in news:3fpsc5dq1ukq64bsnl9cqi3f91tuvjtlct@
4ax.com:
I figger it's 0.
0+0+0=0 0x0x0=0 0^0^0=0 (logic) 0v0v0=0 (logic)
When I checked my neighbors' pool today I got a constant reading on my ruler, precise to .5mm or so. There was some rippling where filtered water was being returned to the pool, and the wind may have been 1 mph.
On a day when the water temperature was 85F and the dew point was 60F and the wind 10mph, if it took hours to raise the water level, I imagine you could lose enough from evaporation to make area calculations meaningless.
I don't have a pool so I may be missing what you are saying. I am reading that you are measuring the difference in the pool level when you add water.
I really doubt you can measure to the nearest mm. If you can the possible error is plus/minus 0.5 mm. To measure the height increase to
1% you would have to add 50 mm of water (0.5 mm possible error is 1% of 50 mm). (That excludes temperature effects, evaporation and accuracy of the water measurement.) Converting, 50 mm is about 2 inches. Might be more practical when you are filling the pool.
Agree
If designing in 3D no need to use ACAD any more anyway. Get a solids modeler like Solid Works
The ONLY thing I would use CADA for now days is 2D electrical schematics..... and I'm not even sure I would use ACAD in THAT case!
I spent 12 years using ACAD and will never go back to that again!
I'll phrase my words carefully - what a load! 1/2 millimeter. Please. The water in a bathtub couldn't be measured to that degree of accuracy. The surface tension of the water alone would throw the reading off by at least that much.
Interesting that you would use the word precise instead of the word accurate. Precise has connotations of repeatability, and I have no doubt that your eyes, system and predilections would cause you to read accuracy into something that isn't.
Measuring a volume makes an area calculation meaningless in something where you can't accurately measure the change in depth. If you want to measure an area, measure an area. Don't add another variable and expect it to be more precise or accurate.
R
Why do you keep talking about accuracy? If I wanted to know the water level, I would have to take the meniscus into account. Who cares about the water level? All I need to know is the change.
I've been reading rules to the nearest 1/2 mm for decades, fabricating pieces for household repairs. My readings have always been repeatable.
I'm used to reading the level at the skimmer so I can predict when I'll need to shut the water off. Yesterday I checked to see how precisely I could read. With the material of my ruler, I didn't know if the meniscus would be up, down, or flat. I didn't if it would be hard to see the waterline or if the level would move.
As it was, the change in color made a distinct line across the white ruler. It could be read precisely and repeatably.
In ancient Greece, a philosopher like you would have had a mechanic like me executed for testing a theory by experiment.
Nope, that would calculate volume, not area. Hving been wrong 2 out of 2 I quit :)
Harry K
Why talk about accuracy in a calculation...? Forget it. I have no reply for that.
Household repairs and you're working to two hundredths of an inch? What's your house milled from - a block of aluminum? Again, please. If you're working on a milling machine you measure to the thousandth, almost everything in home repair can be measured to the 1/16, or 1/32 if you're anal. After that it's just wasted.
No. That's not the reason I'd have you executed. :)
R
The skimmer throat is 145mm high. If I wait until the level is 25mm, I can easily add 100mm. If my reading is within .5mm, that would be .5%.
The water comes from a reservoir. Tap temperature is about the same as pool temperature. Anyway, things balance out. The expansion of water is about 3*10^-4 per C. If I added 5,000 liters to 95,000 liters that was 10C cooler, the added water would contract 14.25 liters. However, in warming .5C, the 95,000 liters already in the pool would expand 14.25 liters.
My concern about temperature would be not to make measurements while the sun was high. If while I was filling, the sun warmed the pool 1C, that would raise the level about 1/2 mm.
In summer, the neighbors' pool could easily lose 25mm a week. It can be calculated, based on water temperature, dew point, and wind. At that rate, it could lose about 1/2 mm during a 3-hour filling process.
On a given October morning (and probably most mornings of the year), calculations would probably show a negligible gain or loss.
Go the the mfr; he'll have all the figures AND usually a method to calculate. Try other mfrs if yours doesn't have the calculators. They do exist.
Still got the paperwork? It's in there too.
Or, lay it out on grid paper and count the grids, remembering to take into account any depth changes. Might need a little algebra for a shallow to deep slope.
HTH,
Twayne`
I used to calibrate Simpson 260s. The accuracy left something to be desired, especially on AC. Cheaper meters may have been equally accurate, but the meter movement and mirrored scale made the 260 more precise. Precision was very desirable even if the accuracy didn't match it.
Pushing a ruler against the skimmer throat won't tell me accurately where the water level is, but as long as it gives precise, repeatable readings, it will tell me the change in level. Change can be very useful for calculations.
Don't you ever use stacks of playing cards as shims or gages? That gives you a resolution of about .25mm.
If you're repairing something and need the piece to fit, it may be worthwhile to read a rule to the nearest .5mm. It's roughly 1/32".
I decided decades ago that 16ths and 32nds were anal. They require working with fractions of five denominators. Harder to read the rule, harder to remember, harder to write, harder to add and subtract.
The correct way of doing it would be to draw out the two circles that make the upper and lower part. Find the area of those two spots, then subtract out the arcs that are over lapping.
I checked again to day. The owner had cleaned leaves from the skimmer basket, so there was more rippling from the return jets. It looked like
1mm peak-to-peak in the skimmer throat.Measuring at the bottom peaks gave repeatable results, but it wouldn't work to measure a change in level at the skimmer with the pump going. Water velocity would affect the reading, and the velocity in the skimmer throat would slow down as the level in the skimmer rose.
It looks as if I couldn't guarantee to calculate the area of the pool within 1% this way. I don't even know how accurate a municipal water meter is. However, it requires only two ruler readings and two meter readings, and the results could be accurate to 1% or so.
Now suppose it's a rectangular pool 5 x 10 meters, and your tape readings are 1% high because of sagging of the tape and rounded edges on the pool. Your calculation will be 2% too high. If in addition the corners of the pool are rounded, the calculation will be more than 2% too high. Even for a simple rectangle, it might be more accurate to calculate area by measuring a change in depth of 100mm or so.
Below are the basic calculations to work out your swimming pool volume. These figures are useful when chemicalizing your swimming pool.
If measured in feet: Rectangular swimming pools - Length x Width x Average Depth x 6.25 = Pool volume in gallons Circles/Kidney shaped swimming pools - Length x Width x Average Depth x
4.54 = Pool volume in litres For all shapes measured in feet - Gallons x 4.54 = Volume in litresIf measured in Metres: Rectangular swimming pools - Length x Width x Average Depth x 1000 = Pool volume in litres Circles/Kidney shaped swimming pools - Length x Width x Average Depth x
1000 x 0.79 = Pool volume in litres For all shapes measured in feet - Gallons x 4.54 = Volume in litres If measured in meters - 1 cubic meter = 1000 litresAbove Ground Swimming Pools Fast Set / Steel Frame
10' x 30" = 1000 gallons 12' x 32" = 1185 / 1520 gallons 15' x 36" = 2240 / 2780 gallons 18' x 42" = 4200 / 6076 gallons2 ways --
Actually, I like the "draw it out on a piece of graph paper and count the squares" method.
A GPS that will count that short a distance, and calculate an area as small as 500 square feet? I want one!
Steve
It may be pedestrian model. Best suited for city slickers. These can help navigate short distances and home in shorter distances.
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