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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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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)
9 A, s) l$ o+ [1 \( r# lThe 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), B% l) K+ F. U4 o6 N, H/ p# {
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:
) a# `, S# i& o1 O9 f' gHow do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
4 u/ W) T" q+ j2 }/ N+ LI call this is JACK LAI Spiral Method 螺旋法
+ c7 K% r8 z" M3 [. ?# ^) u0 v' mThe outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.# P* w7 n5 E/ W# E3 z
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.
/ D* ]$ C& x+ v' C7 sBecause the pipe is horizontal, position 0 can not be placed. See figure 2' e9 [" g; D. L: y2 ]
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+ X; g. q [9 q% b
The total heat trace that can be installed here is about
" i9 D" g" b4 \2 w9 a1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
# M. |) ~( Q* D5 k+ f L. lSo, the 9.4 meters heat trace can be installed along the 3 inched 1.4 meters pipe without a problem. , r' j- V* |1 C# s z8 b$ U
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Note :
M9 U" b) D4 \' }1. The minimum bend radius:; q# o' d& B% A) r$ s6 b ~, v7 H3 F
Because the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
/ v; n6 X. m6 X7 S5/16 *6 = 30/16 almost = 2 inches& m6 r( `. t! `) c
So the maximum bend radius is 2 inches.' n* h" Q5 Y S9 I2 `/ b! p
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As regular
4 g0 r z3 |, pFor 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* q! @: O# f4 c+ t5 x- t
if the pipe is horizontal, The length of heat trace can be installed is about" }9 o& _+ g) _: \6 x
1 * 9 = 9 meters1 F E- z$ T( q0 L6 ^1 ^
If the pipe is vertical, The length of heat trace can be installed is about8 x8 J9 G) \. S& C
1 * 10 = 10 meters. 5 @7 C- T$ z% S8 l) g! ~
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; h& I! d+ ^: @
if the pipe is horizontal , The length of heat trace can be installed is about7 d$ W$ m1 U% Q% k f
1 * 4 = 4 meters
8 k: d: w$ u& d' S7 U' S# j2 fIf the pipe is vertical, The length of heat trace can be installed is about! f q& G; A3 j& w
1 * 5 = 5 meters. |
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