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发表于 2010-7-10 17:18
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本帖最后由 jack_lai 于 2010-7-10 18:52 编辑
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足球看完了来看看题目。$ f" y* E! n8 J ?1 o; I0 b
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The length of the heat trace is 22 meters. The size of the heat trace is 5/16 inch (WATTS/ m SUPPLIIED is 43.7)( f/ |. {: B: R+ M. z0 a1 f
The drawing is shown as figure 1. (All data is from the memory. They are not the same as the real drawing, but a little bit different)
/ \% n9 C W. a% p4 }9 e' KWe can see it is not easy to install the 22 meters heat trace according as figure 1' j$ B/ ^7 S3 b( \
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As a normal question we just discuss:
, V, k; c( X! L$ i' S. m' YHow do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
& d- @: Y0 h5 i) {I call this is JACK LAI Spiral Method 螺旋法
" ~; Y5 u" e U1 Q; C. h4 g. N. rThe outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.
. i* u/ @. k& PThere are 10 positions to plac the heat trace. They are 0.1,2,3,,,,,9. The distance between each position--heat trace is about one inch. 5 l' L% x8 y: Y* k K" A* ]+ Z7 Y
Because the pipe is horizontal, position 0 can not be placed. See figure 22 L- Q: S# a- f; n
Because the maximum bend radius of the heat trace is 2 inches( see note 1), position 5 can not be placed. See figure 2. Then the route of the heat trace can be like figure 3 L! e! Y& u. d$ F
The total heat trace that can be installed here is about 7 B# a" D+ g( ] l# @
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
$ o L8 W: z1 y0 w9 ~9 XSo, the 9.4 meters heat trace can be installed along the 3 inched 1.4 meters pipe without a problem.
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Note :
! q. N7 _, g( W9 W1. The minimum bend radius:
) q* H- U: M4 \7 q8 t* T; pBecause the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is8 ~: u# j; C* O% i
5/16 *6 = 30/16 almost = 2 inches
' j+ m2 R* q, f% m: `/ j+ n( {/ \1 J$ hSo the maximum bend radius is 2 inches.
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, \! L% |! B! V/ ]5 y: l" sSummary
/ {3 a% j# Y# OAs regular
4 @, d# {/ x6 Y# n; i& h5 aFor 3 inch pip: If heat trace size is 5/16 inch, and no RTD, the box position is close to the end of pipe. 1 meter long pipe
) I% Y6 b# i2 Z& e( \if the pipe is horizontal, The length of heat trace can be installed is about1 g8 Q$ s7 h: K2 [9 _+ f
1 * 9 = 9 meters
3 A! x# C; B+ P$ R, fIf the pipe is vertical, The length of heat trace can be installed is about
& f& D9 @9 S) ?& h/ }$ i1 * 10 = 10 meters. ; H( u+ D% ^* s
For 2 inch pipe: If heat trace size is 5/16 inch, and no RTD, the box position is close to the end of pipe. 1 meter long pipe0 i# l' l- l; g K, F; \ i
if the pipe is horizontal , The length of heat trace can be installed is about' \) v2 S o4 e1 b" O' `2 g
1 * 4 = 4 meters7 A7 r, x8 f4 y
If the pipe is vertical, The length of heat trace can be installed is about' h; D: @- D; H. J7 J4 ~
1 * 5 = 5 meters. |
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