I'm trying to source my pool equipment o-rings by trade sizes and material.
I've figured out all the trade sizes; but does anyone know the material?
Buna? Viton? Nitrile? Silicone? Butyl?
Does it matter?
If nobody knows, I'm going to go with Viton; but it would be better to
know for sure what the OEM material is for pool pump o-rings.
On Sat, 25 May 2013 06:56:48 +0000, Danny D. wrote:
Of the zillions of o-ring reference for pool pump parts on the web,
this is the only one I've found, so far, that mentions the material.
On Sat, 25 May 2013 08:19:11 +0000, Danny D. wrote:
This listing also mentions pool o-ring material; but it is confusing at best.
24850-0009 Sta-Rite Tank O-Ring - System 3 Filter, 25 inch diameter
The o-rings listed are made from Buna, Viton or EPDM compounds.
All pool o-rings are made from Buna unless otherwise stated.
If you are running a chlorine system and can not locate the Viton o-ring
that you need, please contact us to make sure one is available.
From that, I can't tell if pool o-rings are buna or viton.
On Sat, 25 May 2013 08:30:21 +0000, Danny D. wrote:
This pool o-ring blog implies they're EPDM (but they seem to have
their facts wrong on Buna-N so I can't really trust their advice).
"Swimming pool pump and filter o-rings are typically made with EPDM rubber,
while chlorinator o-rings are usually made of a Fluorocarbon, Viton or FKM.
Some more expensive types are made with a Nitrile rubber, used in Buna type
On Sat, 25 May 2013 06:56:48 +0000 (UTC), "Danny D."
I doubt it really makes much difference. Swimming pool water is about
as benign a fluid as you can find.
When I lived in DC my city water tested "ideal" on a 2 bottle pool
If you are actually in the chlorinator itself, that is a more hostile
This is a reference
On Sat, 25 May 2013 10:46:58 -0400, gfretwell wrote:
I tried calling Aladdin Equipment (941-371-3732) today
to ask what they make their kits out of, since they use trade sizes in their kit
descriptions; but they're not open on Saturdays.
I was thinking sunlight + water + chlorine + acid was the environment.
Note: Sunlight might be eliminated once installed though.
Wow! Thanks. Comprehensive. A keeper! Mostly for metals though.
They list Buna-N (aka Nitrile) & Viton, & maybe Silicone; but not EPDM, nor
Note: They list "Silicon" in the rubber section, so maybe that's a typo?
Googling for o-ring materials, it seems the material choices go in this order:
a. First see if Buna-N (Nitrile) will work (because it's the cheapest solution).
b. If that won't work, use Silicone,
c. If that won't work, use Viton (Fluoro-elastomer),
d. If that won't work, use EPDM,
e. If that won't work, use Kalrez (perfluoro-elastomer).
On May 25, 7:46 am, firstname.lastname@example.org wrote:
Swimming pool water is about as benign a fluid as you can find.
If you want to educate yourself to reasonable level about O-rings &
ring material apps,' go to McMaster Carr catalog and search on O-
If you REALLY want to learn about O-rings
Hint.... my dad & I used o-rings in pools for many years without ever
Pool O-rings ain't rocket science or PhD work.
"I was thinking sunlight + water + chlorine + acid was the
Pool water is nearly drinkable except for the salts / hardness level.
Calm down....you're over thinking (& incorrectly at that) nearly
everything you approach. :(
Ya know...your calls to all the mfr's may seem "free" but the true
cost is coming out of the shareholders or owner's pocket.
Reduce the clutter......
Get some Buna-N's from McMaster & be done.
If they fail (which they won't) replacement with EDPM.
On Sat, 25 May 2013 11:44:42 -0700, DD_BobK wrote:
OK. Makes sense. Pool water is practically drinking water.
I'll go with the basic 50-cent Buna-N (aka Nitrile) o-rings then.
For accuracy, the one thing I need to better understand are
what the trade sizes actually indicate.
The trade sizes don't seem to follow any obvious rhyme
For example, the tiny drain plug o-ring is a 0-39 but the
much larger basket cover o-ring is a 0-12 while the slightly
larger seal plate housing o-ring is a 0-240 and the hugely
larger filter body o-ring is a 0-486.
They don't follow any order that I can discern.
Is the o-ring trade size merely from an arbitrary lookup table,
or is there a definable logic to the trade-size designation?
- ~1" drain plug o-ring (x2) U9-359; trade size O-39
- ~3" diffuser o-ring, U9-37A; trade size O-83
- ~3" filter union o-ring U9362, trade size unknown
- ~2" pre1998: Insert o-ring U9-376; trade size O-113
- ~10" trap cover o-ring, U9-375; trade size O-12
- ~12" seal plate housing o-ring, U9-228A; trade size O-240
- ~25" filter body o-ring 24850-0009; trade size 0-486
Did you visit McMaster?
Attempt to investigate trade sizes?
Or are you asking more questions before doing any due diligence?
I get the strong impression you were the guy (characterization
skipped) who asked a ton of questions in class in lieu of thinking.
On Sat, 25 May 2013 16:48:19 -0700, DD_BobK wrote:
I have read the o-ring charts and PDFs, e.g., this chart:
And this PDF (starting on page 7):
In these charts, the O-### goes up with increasing size of
the o-ring; yet, in the list of O-rings I'm trying to doublecheck,
that relationship does *not* hold true.
If nobody can easily explain why, in a single sentence or so,
that means that they actually don't understand this any more
than I do.
That's OK; but for you to intimate otherwise, without
actually providing that single sentence, implies that you're
in the same boat that I'm in on this sizing discrepancy.
On Sun, 26 May 2013 06:06:57 +0000, Danny D wrote:
I should clarify that statement, by saying that for o-ring sizes
from O-001 to O-050, the designation increases as the size of the
Then the size designation jumps, to O-102, where it starts all
over again, tracking size up to O-178.
Again, there is a discontinuity, until we get to the range
of O-201 to O-284, where, again, increasing size tracks
Another discontinuity; and then we start at O-309 to O-395
for the next set ... until we jump to O-425 to O-475 for the
penultimate set ... and finally, we have O-901 to O-932 for
the final range.
Within a range, the o-rings increase in size with increasing
O-### designation. There are six ranges.
I'll have to dig deeper to see what the variants are that
determine the six ranges. Probably it's a ratio thing of the
key measurements to themselves.
If anyone knows offhand, why the six ranges - let us know
in a single sentence if it's not a ratio thing.
On Sun, 26 May 2013 06:17:26 +0000, Danny D wrote:
Ah, digging deeper, I find the six "groups" are numbered
1, 2, 3, 4, 5, 9 (go figure) corresponding to the O-1##,
O-2##, O-3##, etc., designations, for a total of 369
The first five groups are (mostly) based on cross-sectional
diameter (ranging from 0.040 to 0.275 inch). Within any one of
those cross-sectional groups, inside diameters range from
0.029 to 25.940 inches, counting upward.
Just to confuse you, the sixth group is organized by outside
diameter in 1/16 inch increments.
REF: SAE Aerospace Standard AS568B
Sometimes it takes more than a sentence or two to explain stuff.
Sometimes people who know aren't willing to spend the time.
Sometimes systems that appear to have no consistency .... really do
have consistency & sometimes they don't. :(
A lot of the time you try to "delve" into things to look for meaning
where none exists. :(
Sometimes things just have to be believed / accepted....
think about the spelling of lots of english word, no rhyme or reason
(sometimes) just have to accept it.
On Sun, 26 May 2013 00:08:05 -0700, DD_BobK wrote:
< OT warning >
My dad taught me that if it can't be explained, it isn't
understood. For example, what a tangent?
Last week, a friend of mine wanted to doublecheck drawings
for trapezoidal-shaped windows where he needed an overlap
of 1/2 inch all around for the window glass dimensions:
He had the numbers - he just wanted to doublecheck them.
He asked me how, and I came up with this simple formula
for the upper overlap (all other dimensions being purely
additive) given the symmetry of parallel lines, geometric
angles, & high-school trig:
Side1=tangent of (90° + angle°)/2 * 1/2 inch overlap
Side2=tangent of (90° - angle°)/2 * 1/2 inch overlap
He checked all his drawings with a calculator proclaiming
the answer correct. He then googled what a tangent was,
and apparently he got the answer that it's the slope at
any point of the curve.
He called me back, asking "What's a tangent?" because
the fact that it's the slope of a curve doesn't help
him understand what it is. Sure, he saw the graph of
a tangent on the web - but that didn't help him understand.
You know what I told him?
I said draw a one-inch right triangle with a 45° angle &
note the sides have a ratio of 1:1. The tangent of 45°
is simple the ratio of the opposite side over the adjacent
side. Now change the angle to 34° (which was his angle),
and you'll see the same ratio holds true. So you have
an equation where if you know two of the three components,
you can solve for the third. He understood.
I could have waxed and waned with using unit circles and
definition of the slope and describing sines over cosines
(like math teachers do); but, the answer (for him) was as
simple as the relationship of an angle to a ratio.
Note: He then tried to apply the tangent to degrees in
Microsoft Excel, which only uses radians, so I had to
explain radians to him; but I'll just leave that
explanation to your imagination. :)
If it can't be explained simply - it's not understood.
Back on topic, now that I know the O-ring sizing scheme,
I can doublecheck my numbers.
More importantly, for the o-rings that I don't already
have the trade size for, I first measure the cross section
and that already tells me the series (as long as it's not
a boss seal). Then I measure the ID & I have the trade
size. It's that easy. :)
Plus, this method works for all o-rings in the household!
Learning is all the fun (the rest is just work).
And this counts as a "simple explanation"?
Even your explanation of "tangent" (if correct, I didn't bother to
read it carefully) hardly qualifies as "simple".
No disrespect to your dad but...he was wrong.
"My dad taught me that if it can't be explained, it isn't
I fully understand fourier transforms (classical & FFT's).
Can I easily / simply explain them? to you?
No... that's why there's a multi-week course on them AFTER a couple
years study of math.
I suppose I could explain them to you in a few dozens of hours?
Would that count?
On Sun, 26 May 2013 11:04:52 -0700, DD_BobK wrote:
I understand them, and can explain them (to the level that
I need to).
To me, it's simply the ability to mathematically break down a
complex periodic wave into its component sine waves of various
For example, if I take a square wave, I can break it down
into component sine waves of different frequencies; and vice
versa, if I mix the right frequencies of sine waves together,
I get back my original square wave.
I think I know Fourier transforms as well as I need to know,
but if you want to correct my simplification above, I'd be
glad to be the recipient of your largess.
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