I have a polystyrene tube with a 6.25" OD and a 5.95" ID at 75*F.
What is the OD at 50*F?
Thanks Mikek
PS. The wire fell off my inductor when I put it out in my shed over the holidays.
How to calculate expansion of a tube
Dec 08, 2016
12 Replies
First assumption is everything changes linearly.
2F =~ 1K 25F ~ 13K., 13 x 8 ~100, so ~10^-3 x 6" = 6 mil, ans about 6.244"(kinda loose numbers)
George H.
Those damned imperial units.... :-)
OD_50F[in] = OD[in] * ( 1 + LEC[1/K] * 5/9 * delta_t[F])
substitute by numbers.
OD_50F[in] = 5.95 * ( 1 + 8e-5 * 5/9 * ( 25 - 50 ) )
Poutnik ( The Pilgrim, Der Wanderer )
A wise man guards words he says,
as they say about him more,
than he says about the subject.
I see you used ID at 75*F in your calculation, I want to know the OD. Can I change 5.95 to 6.25? I'll admit I'm clueless, very weak in math.
OD_50F[in] = 6.25 * (1 + 0.00008 * 0.5555 * -25) OD_50F[in] = 6.25 * (1 + 0.00008 * (-0.00004444)) OD_50F[in] = 6.25 * (1 + (-0.00000000355) OD_50F[in] = 6.25 * 0.9999999645 OD_50F[in] = 6.2499999778
If 6.24999999 is true the Polystyrene shrinking was not my problem. The copper wire should have tightened when it was in the cooler shed. I find the copper wire shrinks ~0.003 per 19" (per turn) Instead the wire got loose and slid off their proper spacing. Oh well. instead of cooling my tube, I'll heat my wire. Please make corrections if needed.
Thanks, Mikek
Where did you get 2F? I'm looking at 75*F to 50*F Thanks, Mike
Sure, you can. It is proportional.
Error. How did you get 0.5555 * -25 = -0.00004444 ??? It is cca 13.89
Final result for 6.25 should be 6.243 in.
BTW, if you have input data with accuracy max 3 digits, it does not make much sense to express results in more than acout 4 digits.
Poutnik ( The Pilgrim, Der Wanderer )
A wise man guards words he says,
as they say about him more,
than he says about the subject.
e
I was changing units.. 2F =~ 1K so a change of 25F is about 13 K ... times the expansion coef. gives about a one part in one thousand... 6"/1000 is about 6 mil or 7 mil is you like.
George H.
e
one F is 5/9 of one K
so roughly 2F per K
foam or sheet?
that seems to be for foam
This email has not been checked by half-arsed antivirus software
OK, I found my error, Thanks.
So the circumference of my tube would shrink 0.022". if I cooled it 25 degrees. Wow, about 10 times more than the same length of copper wire.
It's a pipe coupler. Mikek
Dne 08/12/2016 v 22:37 amdx napsal(a):
Plastics dilate a lot generally.
Poutnik ( The Pilgrim, Der Wanderer )
A wise man guards words he says,
as they say about him more,
than he says about the subject.
Dne 08/12/2016 v 22:51 Poutnik napsal(a):
That is one of reasons, why is problematic to use ( most of ? ) them for precisely fitting construction components.
Poutnik ( The Pilgrim, Der Wanderer )
A wise man guards words he says,
as they say about him more,
than he says about the subject.
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