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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 & {2 k- }; G6 _- E8 E1 m. \2 @
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足球看完了来看看题目。
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9 N# B. p, `) x" ]8 [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)/ F5 d8 c$ K! ?2 L
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)
+ u- J7 @4 d( w/ a) J+ H) FWe can see it is not easy to install the 22 meters heat trace according as figure 1
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As a normal question we just discuss:; `6 {: p8 @) @5 L
How do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ? ! l' K" R0 @# w ?( e
I call this is JACK LAI Spiral Method 螺旋法" T( @8 ~% }! a0 ?; _! f
The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.8 V: O5 r" T% r) S. j
There 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.
* V ~2 S: F) W" _# S2 R/ ?, CBecause the pipe is horizontal, position 0 can not be placed. See figure 2: j7 K1 }0 T7 B3 c, I1 [7 ]* m5 Y5 }
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- _) T, P5 w6 i2 K, s0 e$ i& x" X
The total heat trace that can be installed here is about 5 {5 f# S: {+ n2 S
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters2 U2 [" a# e8 f4 B: B- f/ {
So, 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 :8 x+ G! s/ T1 Z
1. The minimum bend radius:
, ]$ D, Z$ M6 f1 vBecause the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
/ r* i! `6 I6 v, D# H5/16 *6 = 30/16 almost = 2 inches* \. e/ S; [( m# h5 a9 r
So the maximum bend radius is 2 inches.
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Summary
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For 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! g5 A3 q N4 V9 i5 v% Y: _
if the pipe is horizontal, The length of heat trace can be installed is about
( y& h/ V% F/ \2 K, e3 D9 `1 * 9 = 9 meters7 a4 @* e2 ]- T/ w0 x
If the pipe is vertical, The length of heat trace can be installed is about4 I7 s/ ]( [ p% S! a; Y+ y
1 * 10 = 10 meters.
~2 v6 P5 @* O) W7 }% ?* P9 mFor 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 pipe2 c) _& O {) c p0 W
if the pipe is horizontal , The length of heat trace can be installed is about6 z" T7 \6 v' B, q3 d
1 * 4 = 4 meters0 D: Y' K7 T+ g5 V& K" B
If the pipe is vertical, The length of heat trace can be installed is about
, L$ N5 s% j0 e1 * 5 = 5 meters. |
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