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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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9 n( @) E3 g; ]% u7 R+ [足球看完了来看看题目。
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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)8 T ~ \1 X. \4 |5 Q: N4 U' a3 Y
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)2 y& u* F7 q; y Z
We can see it is not easy to install the 22 meters heat trace according as figure 1! J! Y5 D7 C4 c. R$ U4 p0 |) k2 K
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- @: l3 h. f" ^/ S; lAs a normal question we just discuss: i0 _+ A7 X; ~3 Z
How do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ? : Q# q/ Q* ~" Q, u: \! D! ~
I call this is JACK LAI Spiral Method 螺旋法1 h3 W' m/ u" g- A2 K9 e' f
The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.
1 L. @7 _8 S) q7 jThere 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.
8 }! J+ w% N4 i9 k& q% z sBecause the pipe is horizontal, position 0 can not be placed. See figure 22 ^/ C9 a. o8 [6 d
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
; r: Q- m/ y4 y: Q1 l- tThe total heat trace that can be installed here is about ) A1 B; a/ g- q$ n
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters0 Z/ l* D" M6 y0 q3 R k+ A% O4 N
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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* B# ^: w% q; m, h/ QNote :+ Q' [, j0 C& c) Q' b1 a) l2 f- A
1. The minimum bend radius:
& _: n* ]4 O- n" S. F# v. WBecause the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is! F: y6 |* p- L/ S% `4 b) T6 @# i* A |
5/16 *6 = 30/16 almost = 2 inches7 n8 ^. f5 G7 \! V" }: ^0 O9 B6 X
So the maximum bend radius is 2 inches.( ] J+ D9 s0 |. v- b6 F: ]
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Summary& n* t3 h+ c9 L- P# O; v
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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, R4 U$ f |: I8 C! s2 J4 I
if the pipe is horizontal, The length of heat trace can be installed is about0 U7 T% l7 M: @ X
1 * 9 = 9 meters( p7 }5 t& s5 K" T
If the pipe is vertical, The length of heat trace can be installed is about. h3 o6 e+ E( P
1 * 10 = 10 meters. ( y5 t+ ^6 Y/ \8 L: Y# P# z U) j
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 pipe
X5 b7 F, ~* J% \if the pipe is horizontal , The length of heat trace can be installed is about% j- N# S! E! c( K# b$ r, N+ T
1 * 4 = 4 meters6 i- O; h6 \9 r# U. c
If the pipe is vertical, The length of heat trace can be installed is about3 n h4 E& X/ j* {- ~; D6 d! Y8 ]/ I- {
1 * 5 = 5 meters. |
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