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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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1# jack_lai 9 |, i8 f- d) i! \4 s; a
# i, N$ {: K1 _- s% I足球看完了来看看题目。& l' ]4 \$ V; R) H
. O. I8 r) ?& W1 ~1 F/ QThe length of the heat trace is 22 meters. The size of the heat trace is 5/16 inch (WATTS/ m SUPPLIIED is 43.7)
5 W' ^! c, {7 n- cThe 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)
, |* [8 k0 E: K `& n. tWe can see it is not easy to install the 22 meters heat trace according as figure 1! Y) W0 d# z l- {
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! H( ]1 F" k5 F" AAs a normal question we just discuss:: U$ V8 I& k8 r6 P: ~
How do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
/ X1 x: I$ j9 z7 a" |/ b% QI call this is JACK LAI Spiral Method 螺旋法) a9 D/ p& Q7 Y/ x$ u
The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.2 h/ d& O$ B. V
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. 3 e o0 e1 @/ H V
Because the pipe is horizontal, position 0 can not be placed. See figure 2
: k- j% X8 t( x7 o! }( OBecause 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+ J" n2 z$ }3 J/ ]
The total heat trace that can be installed here is about . A' ^4 ^% N1 Y8 Y$ W7 e0 ]2 R
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
5 i# {7 {; m8 S# ~So, the 9.4 meters heat trace can be installed along the 3 inched 1.4 meters pipe without a problem. 3 \* `' e# p: N
7 \. z' h8 B: G- \+ }Note :
' E" v3 F/ s7 G* b% J! ?1. The minimum bend radius:8 {' F, S- P( u. t* L
Because the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
& ^: j9 v: l# Q9 y/ L% t/ H3 j2 p+ G5/16 *6 = 30/16 almost = 2 inches! Y% ~% p1 E. O, F+ L( g5 Z
So the maximum bend radius is 2 inches.+ G" \. w4 e( P) R" ]6 Z
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Summary+ J; W' n: _+ y, ?7 `3 e1 N7 N. G
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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) {% |0 ?( X. T; Z# C" i
if the pipe is horizontal, The length of heat trace can be installed is about
! R1 J9 c+ u/ Q1 * 9 = 9 meters) `: j1 U/ f& X2 m
If the pipe is vertical, The length of heat trace can be installed is about8 P! H1 m$ N8 X! ^# I
1 * 10 = 10 meters. 6 S7 B5 A' R% Q2 z6 Q( _% y1 I
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 pipe1 Q( {' o2 Y4 r: u, j4 A
if the pipe is horizontal , The length of heat trace can be installed is about
3 ?# E9 \. p* e y7 S3 f; x* P- \1 * 4 = 4 meters
6 F% W5 M3 S% C; I H# XIf the pipe is vertical, The length of heat trace can be installed is about; T- b1 R. s% q( O1 s A
1 * 5 = 5 meters. |
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