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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。
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; h/ h7 `" u/ l4 x' ZThe length of the heat trace is 22 meters. The size of the heat trace is 5/16 inch (WATTS/ m SUPPLIIED is 43.7)
' ? L8 @( a% M, m0 Z/ C& Y: hThe 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)/ B2 M" o) N! w7 j$ e% j& M, Z
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:' L7 H7 X k; O3 ^5 b- v, `9 |! V
How do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ? 9 g8 `% W% w+ A
I call this is JACK LAI Spiral Method 螺旋法* p1 X5 o7 K9 S) j N
The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.7 L6 w* K; l) e+ g# B8 E, C* 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.
' H! P5 ^. s+ k# ZBecause the pipe is horizontal, position 0 can not be placed. See figure 27 ]. X( T" t1 @. K; |
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
) q$ V% m* ^2 l. w9 S* y( W4 e" H: LThe total heat trace that can be installed here is about 0 Q4 k* w& l1 M% a. j% D0 w
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
1 y' l3 b7 A- T% u4 s# {; dSo, the 9.4 meters heat trace can be installed along the 3 inched 1.4 meters pipe without a problem. % S5 P1 G: S+ ?) T- M, D
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Note :
0 v* \: [4 V. T+ M4 a& J1. The minimum bend radius:% B) h0 Q( F2 ~* W+ p
Because the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
- V# N, N' O8 ]" u8 m4 z: O* ]5/16 *6 = 30/16 almost = 2 inches- u6 e p+ E8 G3 Y' _6 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 pipe9 F5 w! X; D; o4 N1 P
if the pipe is horizontal, The length of heat trace can be installed is about
& f. E3 P9 c, A5 \/ k1 * 9 = 9 meters6 m; T1 r1 R8 {& c2 _
If the pipe is vertical, The length of heat trace can be installed is about/ N! F- g. R0 m6 x( J
1 * 10 = 10 meters. 2 e0 I" Y, T' O2 x0 D; U* F" w8 w
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 pipe7 F9 M1 N! U5 r& h6 o5 ?
if the pipe is horizontal , The length of heat trace can be installed is about
2 h9 S3 f9 t# o7 ^1 * 4 = 4 meters
$ B" ?8 _) c4 G7 K& n3 MIf the pipe is vertical, The length of heat trace can be installed is about
- e+ ?( Y P1 n) S6 H1 * 5 = 5 meters. |
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