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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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* k% S& V0 F5 E0 z7 D/ r9 M足球看完了来看看题目。) |0 ]& w N3 g3 T1 G( O
5 V$ N$ G) v* u3 _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) V8 n/ R+ ^( c- S8 c! G/ ?7 D5 _
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% G7 M" V( A% i( HWe 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:
: p) d6 n# \9 _9 [6 W* h1 IHow do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
" _1 S! I9 W1 E$ QI call this is JACK LAI Spiral Method 螺旋法
! Y/ q* a$ E8 c' G. J `The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.
/ i/ Y' p) g3 f! |/ d) cThere 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. / N/ g' z8 ?6 Z, o0 Y( y
Because the pipe is horizontal, position 0 can not be placed. See figure 2
8 P" S, L" `5 g; o& o4 t" y4 f0 FBecause 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 38 N5 i3 y7 \4 D
The total heat trace that can be installed here is about
% p4 a$ H+ R) U$ K/ g1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters' K/ b8 u: B, G/ K: O
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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5 `! W" N0 X9 }+ LNote :
- W' H$ ? Q1 ?. i1. The minimum bend radius:# z* a* S5 |) S) v! o" I
Because the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is1 g1 l7 D7 @) o6 H* p) s
5/16 *6 = 30/16 almost = 2 inches; h9 W" _2 d! v p1 e7 Z1 k
So the maximum bend radius is 2 inches.: `% W) M! ]$ Q2 ?5 _$ z
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Summary
9 G, S T+ E+ K5 U8 T6 EAs regular
+ H0 v- z* Z9 f8 ]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
& Y" m. ]9 ~, c- dif the pipe is horizontal, The length of heat trace can be installed is about; x9 z8 P9 ^0 J0 `# N5 ~
1 * 9 = 9 meters( o8 Y8 V3 g. z$ u, d y
If the pipe is vertical, The length of heat trace can be installed is about
S8 K N3 [ Q: v7 q9 W3 ~2 w1 * 10 = 10 meters.
) p2 \8 V4 I% GFor 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* K; J- B% L5 v$ j+ |4 v9 s
if the pipe is horizontal , The length of heat trace can be installed is about. P: R5 b/ j% G3 ~* B" Y, U2 ^" x3 Z
1 * 4 = 4 meters! ^9 l' U: G- x. Z# Q8 d& o7 w. U
If the pipe is vertical, The length of heat trace can be installed is about
6 A, }- g/ J% [( t/ k; K1 * 5 = 5 meters. |
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