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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 9 P/ S: {& X$ @) C/ N) t
# F8 ]# U, \" y 1# jack_lai
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- |& @' l6 J! k- e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)
3 [# w% _# V* ~" o2 G) fThe 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+ L9 k" _* N7 G9 B2 c8 Y* v
We can see it is not easy to install the 22 meters heat trace according as figure 1
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) ~1 c0 B9 w# UAs a normal question we just discuss:
# ?# H7 u, X' H# XHow do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ? & n7 R% q! C5 W) ~* X# q9 T# w+ v, U4 Z
I call this is JACK LAI Spiral Method 螺旋法/ z& P" d9 a( _
The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.
2 Z8 t" x3 E# m$ l! G' vThere 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.
1 Z. i( A0 p8 n; `Because the pipe is horizontal, position 0 can not be placed. See figure 20 R: i5 U: Q& H7 p+ X, m
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& w7 ?0 |: O0 W. ^2 T/ L
The total heat trace that can be installed here is about 1 q6 n9 R1 z# j! h- i
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
' X5 `' R, m0 ISo, the 9.4 meters heat trace can be installed along the 3 inched 1.4 meters pipe without a problem.
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+ I* F2 {# m- yNote :, e3 n: x R7 T4 K. }' L3 c
1. The minimum bend radius:
4 Q- f& s, G( B/ a6 wBecause the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is4 H9 k9 s+ I& c* B) d
5/16 *6 = 30/16 almost = 2 inches
+ u3 e( n$ [6 ?. \3 V2 Z* \) SSo the maximum bend radius is 2 inches.
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Summary
7 C. H2 C* a0 i5 EAs regular
/ y2 \4 P( N0 A5 D- Z" a6 MFor 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
7 j9 u% r9 N2 o# n- O7 cif the pipe is horizontal, The length of heat trace can be installed is about
3 n- h1 S+ C; @) B e; Q# \1 * 9 = 9 meters
0 s o7 \" m! J' E. N1 KIf the pipe is vertical, The length of heat trace can be installed is about. Q; R* k+ F" E6 q0 D, Z& [
1 * 10 = 10 meters. % O) L) y" }& `& u5 V9 W. b
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: @0 R8 b2 }, [* G$ o+ d. m* x
if the pipe is horizontal , The length of heat trace can be installed is about( ~7 F6 J( L( A
1 * 4 = 4 meters3 U9 \0 T' j# H! C5 |+ f
If the pipe is vertical, The length of heat trace can be installed is about
" [0 e3 h' u& F( b1 * 5 = 5 meters. |
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