# What material is used for pool equipment o-rings (buna? viton? nitrile? silicone?)

On Mon, 27 May 2013 14:36:24 +0000, Danny D wrote:

BTW, I don't think I've *ever* needed Calculus in my daily life.
For example, I've never taken the derivative of anything in order to do something; nor have I calculated the integral of anything for practical purposes.
I'm sure *you* have, given your theoretical & practical background; but I just never needed it.
Still, it's nice to know the simplest things, e.g., the integral is the area under the curve and the derivative is the change of the output given a change in (usually) time.
That's just about all *I* need to know about Calculus (but now we're straying far too much away from the topic).
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On Sun, 26 May 2013 21:51:07 -0700, DD_BobK wrote:

BTW, on purpose, I had purposefully described the Fourier series, and not the Fourier transform (which converts that series into an algebraic equation).
And you didn't even mention that!
It was a test. Just like yours.
:)
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DDD-
That's why I figured it was a "cut & paste"
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On Mon, 27 May 2013 23:30:50 -0700, DD_BobK wrote:

Naah. All I know about the Fourier series is that this Frenchman figured out that every periodic wave was composed of just sine waves of various frequencies. That's pretty ingenious to figure out.
And, of transform, whew! It's a beast. I've never needed it outside of academia; but it's great for an algebraic reduction of complex differential equations. Luckily, I only took the first year of college calculus, so we really didn't deal with it other than theoretically.
It's used in the EE class I'm auditing though, but again, only at the theoretical level.
Starting in the fall, I'm taking organic chemistry, which should be a lot of fun!
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I certainly hope you're a paying customer.......
I pity the instructor & students who will be sharing lecture time / space with you. :( BTDT... the S/N is going to be unbelievably panful.
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On Tue, 28 May 2013 07:30:03 -0700, DD_BobK wrote:

Yes. You can't audit without being registered, and, you must take all exams and do all homework.
The only difference is the grade is Pass/Fail (and the fact I'm three times the age of the students, and, often twice the age of the professor!). :)
I have one advantage over some students, in that I have an application in mind when the professor discusses things - and I bring that to the table.
When I show the math, I show everything, down to the last detail - for which I've received kudos for in these classes.
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wrote:

Definitions differ. When I was in college (and indeed when I was an instructor at a different, private, college) "Pass/Fail" and "Audit" were completely separate modes. "Pass/Fail" was as you describe. "Audit" didn't require exams, though they were voluntary. Professors couldn't stop someone (indeed didn't know) if someone was taking the course "Pass/Fail" but could and certainly did, if they wanted to audit a course.

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On May 28, 10:22 am, snipped-for-privacy@attt.bizz wrote:

IME, as well, aduit is much different than Pass/Fail......
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On Sun, 26 May 2013 00:08:05 -0700, DD_BobK wrote:

You're forgetting that some people love to learn!
In fact, learning is more fun than actually doing the work.
For example, learning about how unions sealed using boss o-rings while NPT threads seal with goop was more fun than getting that goop all over my fingers.
Specifically, learning that the union o-rings are measured differently than the sealing o-rings is more fun than twisting unions together and not having them leak.
The meaning is in the learning - not in the work itself.
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DDD-
You're assuming facts not in evidence
"You're forgetting that some people love to learn! "
I'm a life long learner & I appreciate that in others. It is my impression that in your case the slope of the learning curve is so flat as to be indistinguishable from zero....
Now that Oren has divined that you are retired .....all I can say is "oh goodie".
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On Sun, 26 May 2013 10:56:22 -0700, DD_BobK wrote:

I like Oren. I really do. But he still scares me!
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I respect Oren's contributions... he in no way scares me
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On Sun, 26 May 2013 21:51:53 -0700, DD_BobK wrote:

You must be Aspergers. Oren gets the joke. You don't. Oren helps. You don't. I like Oren.
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I tried to help...but you waste people's time. I try to return favors.
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On Sun, 26 May 2013 11:37:13 -0700, Oren wrote:

I never worked on a home before.
In the beginning, I rented. Later on, I didn't have the time, so I paid. Then I left my life-long profession (good riddance) and bought a run-down fixer-upper hidden deep in the mountains, so now I've got the three incredible ingredients for DIY home repair:
I. An old house II. No money III. Lots of time!
If you didn't have the first, there'd be nothing to fix; if not the second, I'd just pay someone else to have all the fun; and the third is a prerequisite to spending more time learning how to do the job than doing the job itself.
PS: The fourth thing you need is an nntp newsreader & server and good friends who care about and understand you! :)
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Bummer about spending your life doing something you hated...... :(
"left my life-long profession (good riddance)"
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On Sun, 26 May 2013 21:54:03 -0700, DD_BobK wrote:

I should have been an engineer - and - have just finished auditing a semester's worth of classes at the local college.
Passed it all (Pass/Fail grade only) and loved designing MOSFET and BJT amplifiers; but had a tough time with poles and zeroes.... :)
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Maybe you should have been...might have injected some logic into your problem solving methods. Those labs & report writing can have amazing influence.
Suggestion: Stick with ME courses....more applicable to DIY home repair. Though, welding, wood shop & basic electrical would be more helpful.
Tip: Systems are unstable when poles are in the right hand plane. :)
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On Mon, 27 May 2013 23:45:50 -0700, DD_BobK wrote:

I have an old arc welder, and oxyacetylene tanks that I picked up at a garage sale. It's night now, but I can snap pictures of them in the daylight for you to see. I haven't used them though, and I don't even know if they work. Haven't even checked the hydro dates on the tanks - but the goal was to be able to weld when/if I ever needed to (my steel water tanks are leaking).
Took wood shop in junior high and high school for far too many years. Now that I'm older, I realize that it's better to take a bunch of different classes in high school than the same class over and over again, because you don't know what you like at that young age.
Read all the SAMS books ages ago on basic electronics, and even built a few 68701 Motorola microprocessor boards as a kid. This was before PCs, of course, when you *had* to build your own boards. But I forgot most of the assembly language stuff long ago (load accumulator A, push and pop data off the registers, etc.). Yuck.
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On Sun, 26 May 2013 00:08:05 -0700, DD_BobK wrote:

You'll note that I strive to not misspell words in my posts, and that I punctuate my sentences as well as I can - and that all my posts are readable & responsive (if a bit verbose).
So, even if I'm asking about something as mundane as how to properly plumb a shower stall, I take pains to use the English language as properly as I know how to use it.
It's all part of the enjoyment of understanding what is being said and done. In fact, you'll notice that I even have an ancillary thread on the English-usage newsgroups asking how the word "plumb" came about; it's interesting that the term comes from hanging lead balls (i.e., plumbum) on the end of a string.
Learning just *that*, was more fun than the actual plumbing of the shower stall. :)
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