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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。6 s( X* i" Y* X
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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)
6 H6 v, Z, P- zThe 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)
# K/ g) I5 G# g- s! L) iWe can see it is not easy to install the 22 meters heat trace according as figure 1
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2 `0 ~* }; j; o! F0 a) Z5 I( K9 }As a normal question we just discuss:" R2 R8 Z, v0 Z1 V A% v" J- Q- ]
How do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
9 o3 \( ]/ f" V& jI call this is JACK LAI Spiral Method 螺旋法8 v, S/ p9 f+ |. R+ }( x1 W
The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.* G, |6 a9 |* `, [( l
There are 10 positions to plac the heat trace. They are 0.1,2,3,,,,,9. The distance between each position--heat trace is about one inch.
9 U, L X1 P4 f }Because the pipe is horizontal, position 0 can not be placed. See figure 2) u: b- e$ A2 j/ A, g2 E
Because the maximum bend radius of the heat trace is 2 inches( see note 1), position 5 can not be placed. See figure 2. Then the route of the heat trace can be like figure 3
6 [4 t3 g6 x) C5 CThe total heat trace that can be installed here is about & z. w% @" F4 R" K' \
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters
! x2 ]* P, F4 b# q2 L qSo, the 9.4 meters heat trace can be installed along the 3 inched 1.4 meters pipe without a problem. / b. e8 K2 h q* T3 E
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Note :/ e. U5 g4 ~; q, c! v
1. The minimum bend radius:5 l, l( \1 U1 a# X% f+ F% E
Because the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
, W% o1 D3 ~) j3 i3 O7 j5/16 *6 = 30/16 almost = 2 inches
5 H! O. F" P/ e+ d% Q; jSo the maximum bend radius is 2 inches.$ Q& }% v# g" @) W
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For 3 inch pip: If heat trace size is 5/16 inch, and no RTD, the box position is close to the end of pipe. 1 meter long pipe
* `0 Q/ B) @+ _' m- E9 _* Nif the pipe is horizontal, The length of heat trace can be installed is about9 K2 b% {7 \3 T! N! z" U: P- g
1 * 9 = 9 meters. {0 S& h; K6 q$ h
If the pipe is vertical, The length of heat trace can be installed is about- j; T% F( r' k3 m% g& G( ]
1 * 10 = 10 meters.
( m5 ^9 Y; i/ S6 I( L& O2 bFor 2 inch pipe: If heat trace size is 5/16 inch, and no RTD, the box position is close to the end of pipe. 1 meter long pipe
' \) s5 C2 y, P4 kif the pipe is horizontal , The length of heat trace can be installed is about, e; n& g6 A& M8 g! l5 c
1 * 4 = 4 meters% H# V, |: h" ] R
If the pipe is vertical, The length of heat trace can be installed is about
' U! ? \" K% h2 k) t1 * 5 = 5 meters. |
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