GE T17, Руководство по установке

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Chapter 2. Installing the Pipe Nozzles
26 Model T17 Installation Guide
2.3.3 Determining and Marking the Second Nozzle Location - MR1 Mid-Radius (cont.)
4. Mark a line on the piece of film at a distance AS from the left edge, as shown in Figure 34 below.
Figure 34: Film Cut to Size and Marked
•
Example:
To demonstrate the calculations, consider an
MR1
installation for a STD Schedule, 48” pipe .
a. From standard pipe tables: pipe
OD = 48.000 in.
and pipe wall thickness
(W) = 0.375 in.
b. From the 1st equation:
Y
0
= (48.000 - (2 x 0.375))/2) x 0.5 =
11.813 in.
c. From the 2nd equation:
X
0
= SQRT ((48/2)
2
- (11.81)
2
) =
20.892 in.
d. From the 3rd equation:
β
= ATAN (20.90/11.81) =
1.056 radian
e. Thus, AS = 48.000 x 1.056 = 50.697 in. ( Note that this is the same value listed in Table 4 on page 27 .)
Note:
In the above example, the tabulated pipe OD of 48.000 in. was used in the calculations for clarity. Ideally, the
measured average pipe OD from step 2 on the previous page would be used instead.
S
L
AS
Mark Line
Y
0
D 2W
–
2
-------------------
 
 
Chord Location
( ) ×
=
where, W = 0.375 inches and Chord Location = 0.5
X
0
D
2
----
 
 
2
Y
0
( )
2
– =
where, D Average pipe OD (see step 2)
=
β
(radian)
X
0
Y
0
-------
 
 
 
atan
=
AS D
β ×
=
where, D Average pipe OD (see step 2)
=