鲜花( 0) 鸡蛋( 0)
|
楼主 |
发表于 2010-7-10 17:18
|
显示全部楼层
本帖最后由 jack_lai 于 2010-7-10 18:52 编辑 + z. j, N' ]/ a4 l* a! @# x
{ x" v; M n. m G$ K7 t
1# jack_lai
+ _9 b4 r5 }% j( K' D/ g$ X, g9 b% S6 M' a" s
足球看完了来看看题目。: S! q$ A$ N: J1 C1 t( M
- W5 z( @# N# V) n) X5 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)6 O- P) Z; B" V( Y" b
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)
1 A2 \2 u( A( OWe can see it is not easy to install the 22 meters heat trace according as figure 1
& P6 s2 y& t/ \ T3 @! A/ z4 k3 R" Y! g! |' o1 J3 C
& `8 V% `- `& \: b) K. y8 e
2 @. H. V# s3 p' `4 C* U( S. }/ ~. x7 _: C
As a normal question we just discuss:
2 e% j! B- T3 ]How do you run these 9.4 meters heat trace (size 5/16 inch) on the 3 inches 1.4 meters pipe ?
! B; p, G) S) DI call this is JACK LAI Spiral Method 螺旋法
/ y4 J, c3 g1 t: a. l! u) M/ q. _6 B$ b( ?The outside circumference of the 3 inch pipe is more than 10 inches. See figure 2.
9 C& n9 t% x+ m7 G; l+ w8 eThere 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.
% k; Z& M' _9 V) E+ t, xBecause the pipe is horizontal, position 0 can not be placed. See figure 2
6 ]2 A& N& o, f- Y o w- c4 i5 ^# O) wBecause 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
4 b0 L& p r9 r+ I: eThe total heat trace that can be installed here is about : {$ i) B/ ^ U4 ]- l$ k" m
1.4 * 6 + 1 * 2 = 8.6 + 2 =10.8 Meters. j- Z7 l8 o4 b' M, }: t7 W
So, the 9.4 meters heat trace can be installed along the 3 inched 1.4 meters pipe without a problem.
; \# D8 Q% G3 k
) v z+ ~" n- f5 [. lNote :& ? p2 _% T: t% Y7 B. ?8 ?
1. The minimum bend radius:! W+ d9 I$ x5 C0 Z
Because the heat trace size here is 5/16, 6 times the outside diameter of the heat trace is
. |1 r7 x. v+ ]( J5 |5/16 *6 = 30/16 almost = 2 inches$ S5 a5 a/ `$ A g9 r1 K/ d
So the maximum bend radius is 2 inches.
+ C8 ~4 E9 H' _3 Z; M4 a! ^* F
8 [. n8 u/ K3 _5 ~2 e& ?
( T+ X5 {' @/ K2 F
! C+ o) @7 \8 s- m# }) gSummary
/ Y& |3 r2 u( _; x, h6 h5 v. i0 NAs regular
) J' t \ q, U% U" F9 ^( k! `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
: F6 d; ^! R9 m, Fif the pipe is horizontal, The length of heat trace can be installed is about$ j+ S6 p3 _0 F) w! \1 \; \
1 * 9 = 9 meters
) M T6 {. r1 u4 t. l2 pIf the pipe is vertical, The length of heat trace can be installed is about# f9 |: J6 b; }( V
1 * 10 = 10 meters.
6 y: n5 q" s- _/ S" j) B" p9 AFor 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
7 Q0 c; ^! T- @! jif the pipe is horizontal , The length of heat trace can be installed is about
h8 b5 m! ~' N& n: i1 * 4 = 4 meters9 j0 E9 B% ]& ?) m. H! J; K4 a4 e
If the pipe is vertical, The length of heat trace can be installed is about+ d3 a/ G# o9 I+ U
1 * 5 = 5 meters. |
|