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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 8 b0 S% C1 l- {
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1# jack_lai 0 l3 n2 m- a/ _4 W; l
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足球看完了来看看题目。- {3 C8 e7 z5 j7 d' M; W3 u
8 F) }; Q0 m/ w* C0 RThe length of the heat trace is 22 meters. The size of the heat trace is 5/16 inch (WATTS/ m SUPPLIIED is 43.7)) }) f+ z& i( B/ S2 z: U# Q1 T
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)2 J; x& Q: q4 R1 ?0 F% v" ]1 y
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:
: t1 {& w9 c( B0 k4 u, a1 tHow do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
& B: f: M7 n9 X( _, X1 oI call this is JACK LAI Spiral Method 螺旋法
# \, X5 g: y* ?" @The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.
( k e. M4 p9 `3 [4 `" _& mThere 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. $ h8 l3 o/ s9 y' Z& v! G2 A
Because the pipe is horizontal, position 0 can not be placed. See figure 2- q% L, g/ M/ X' r
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
: f5 l# B, \$ {* I# P1 U9 DThe total heat trace that can be installed here is about
$ T( E: Z4 X! e1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
$ v6 ~, S( n2 v9 `+ _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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. q$ Y+ h2 K2 _4 Z/ T% i9 FNote :
2 C; t/ y4 } E7 m# Z1. The minimum bend radius:2 Z4 _: i/ \. N3 g7 f% |
Because the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is* c B3 e" j o6 G* H6 M
5/16 *6 = 30/16 almost = 2 inches9 P6 H" D& A! w9 g' ]0 s' }
So the maximum bend radius is 2 inches.
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Summary; W/ v' y" V3 T8 L
As regular 2 n# Z9 x2 z( n, Y' z) F
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) e |' S6 B2 U$ d* \* ~
if the pipe is horizontal, The length of heat trace can be installed is about
6 q4 f$ B' t+ @; V. d+ n1 * 9 = 9 meters
% Y: ~, ?7 S/ p' G5 Q- q* CIf the pipe is vertical, The length of heat trace can be installed is about
5 |/ }) c, o! o) f1 * 10 = 10 meters.
1 |* G, s" Q! t& s9 U3 H NFor 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' }' U- x# L9 D2 ~* `0 v; F* A0 y" ~
if the pipe is horizontal , The length of heat trace can be installed is about' J Q) F9 R' ]1 s" m
1 * 4 = 4 meters* Q( Z& A3 I5 t) d6 z$ C v8 t
If the pipe is vertical, The length of heat trace can be installed is about
& ^* g. M2 _# u; \! S% N& b' M) N1 * 5 = 5 meters. |
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