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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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/ G0 m1 G; r+ [) C0 W9 C 1# jack_lai
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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)
( b4 ~& G9 z, K- @! sThe 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)
5 {2 \: ~6 |4 U/ d0 |We 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:
. @4 F/ \' F3 ~How do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ? - x6 @6 p+ N( Z
I call this is JACK LAI Spiral Method 螺旋法
) ?+ w5 S3 f7 ?, m. e% r% PThe outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.
8 ` E2 [! f( }2 j' tThere 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. % F' g7 _8 _' W2 n- ~/ y7 f8 q
Because the pipe is horizontal, position 0 can not be placed. See figure 2/ @5 o7 s u* D) L7 d1 j; |
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 36 }' B# z; H/ s
The total heat trace that can be installed here is about
; N4 e8 X) T, ?4 r. ~6 x9 P* X1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
- d7 m, i) s4 P9 |8 f/ CSo, the 9.4 meters heat trace can be installed along the 3 inched 1.4 meters pipe without a problem. , f3 V/ j5 u! X+ {
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1. The minimum bend radius:
. b" g( v+ D6 V$ \: ^ B; RBecause the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
0 S8 B* ~: r# h3 D0 W5/16 *6 = 30/16 almost = 2 inches' [/ C! Z# P9 K4 K# K( _
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
' E9 @9 O& p$ k% d3 ?( Lif the pipe is horizontal, The length of heat trace can be installed is about# X9 L2 }# y; w. Q& S V: O/ J( s
1 * 9 = 9 meters
5 t% [1 H6 b& @# E; c% zIf the pipe is vertical, The length of heat trace can be installed is about
' ~, m3 Q8 G3 C1 * 10 = 10 meters. 0 O b5 f/ ~2 @9 F; b+ I% f9 ?
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
6 Z b6 F4 g5 i( K; P! _if the pipe is horizontal , The length of heat trace can be installed is about
5 v q1 \: ?( {( L" z6 N1 * 4 = 4 meters5 `6 a# _+ L1 ^" b
If the pipe is vertical, The length of heat trace can be installed is about" R4 W/ L( E. x+ ]: b0 v ~
1 * 5 = 5 meters. |
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