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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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: h$ U. b* R/ f, \! ]3 ]! h 1# jack_lai
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足球看完了来看看题目。
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8 D$ w! [2 y5 Z; _0 gThe 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 @) F; z7 B) x( Z
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)
* J# @& X- x! |8 ]7 OWe can see it is not easy to install the 22 meters heat trace according as figure 1
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) ^. j g5 w" S" e. `9 _+ U2 CAs a normal question we just discuss:
0 j$ K* ~; ?2 CHow do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
% R. X4 W' y. h: v2 q. T4 |% MI call this is JACK LAI Spiral Method 螺旋法
+ {3 H: S" t3 o/ [' @The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.- E5 b8 L7 @7 R. d
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.
/ h: F% K! ?9 F3 K% s0 XBecause the pipe is horizontal, position 0 can not be placed. See figure 2; N7 }$ e# b1 ?
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
" Q1 c) [0 h3 r" K! r" xThe total heat trace that can be installed here is about 9 d8 z1 @0 o1 i+ v& j
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters' u7 h: k, e% A) G8 \
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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4 E4 @/ q" I; i: KNote :
n. n5 d3 f1 u1 M1. The minimum bend radius:
. o) _4 q0 K2 {/ V8 Y) z' E9 h1 E7 yBecause the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
3 x6 z% h7 ^3 \! o4 }# H. f5 w5/16 *6 = 30/16 almost = 2 inches
9 t5 Y; N) [$ H7 a/ {2 J' KSo the maximum bend radius is 2 inches.
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, O% E( q# O: T' p' y+ w. Y, H9 r4 GSummary
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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; r, h8 r- V" Z+ O% }
if the pipe is horizontal, The length of heat trace can be installed is about
) A7 U* v- K4 }% j1 * 9 = 9 meters- f, M m' z# h
If the pipe is vertical, The length of heat trace can be installed is about
; H; p4 ?" |( z/ e6 U6 g1 * 10 = 10 meters. 2 G% W0 L- ]/ ^$ s7 N) l4 h E }
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
X& P0 g( x% r0 Y) C, j7 A$ fif the pipe is horizontal , The length of heat trace can be installed is about) R2 J# K! T! M" [' G U) H8 l
1 * 4 = 4 meters
# \ j' M" p% v v. FIf the pipe is vertical, The length of heat trace can be installed is about
: ]4 f, H2 b/ q" J2 J7 X A1 * 5 = 5 meters. |
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