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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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/ w( w6 `6 D) HThe length of the heat trace is 22 meters. The size of the heat trace is 5/16 inch (WATTS/ m SUPPLIIED is 43.7)( y' T; ?4 G9 W; b8 E
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)+ H$ C$ k) M9 l5 c
We can see it is not easy to install the 22 meters heat trace according as figure 1
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( t" _$ E2 l4 H! JAs a normal question we just discuss:
7 L9 q& i# s4 j( b2 ?. |! {' o' ?How do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
& v9 w0 {+ M* Z9 Z1 XI call this is JACK LAI Spiral Method 螺旋法 E# r/ S+ ], Z7 O/ A
The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.
- c! Q; \" s3 i7 v. S$ KThere 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.
% O. }, ~! t0 K8 L- U9 i) xBecause the pipe is horizontal, position 0 can not be placed. See figure 2
7 O# W9 k: t* e3 D* C6 k U b. p8 bBecause 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+ t$ e: f( m' \; y* T# ^
The total heat trace that can be installed here is about 6 B) \, ]9 F$ S, U" ~+ R4 m6 x8 T
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
$ y7 d3 `3 Z$ a* x1 ~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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( l- @& h8 Z; U9 LNote :
$ i8 Z7 r0 G7 h$ t! d/ Q) V1. The minimum bend radius:4 O* V- ~1 E( `' |) Y; f( p
Because the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
" t3 c9 z6 O X- q1 S6 s1 g5/16 *6 = 30/16 almost = 2 inches
/ R2 O+ T5 e7 y; x4 I% T* P9 X/ MSo the maximum bend radius is 2 inches.
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As regular
1 e' i6 P% h; K4 ^. H% I* L* o* XFor 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 pipe2 C/ X# ~/ m' _4 K+ b5 P3 @3 ^
if the pipe is horizontal, The length of heat trace can be installed is about
! ~% v# c* P* H) v5 n, z1 * 9 = 9 meters; K0 X: S5 ]# A w- I' E2 W0 `
If the pipe is vertical, The length of heat trace can be installed is about r$ L, G9 O) V1 C& o: @
1 * 10 = 10 meters. . J, @# L5 K- j- s E" r" T
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/ ?& N% R5 Y) Y' D0 e1 `7 E1 ^* H
if the pipe is horizontal , The length of heat trace can be installed is about1 t* D5 T! h! }! j
1 * 4 = 4 meters" C3 U3 V; p+ `( B
If the pipe is vertical, The length of heat trace can be installed is about/ o$ z6 B# \ l! x! G
1 * 5 = 5 meters. |
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