GE T17, Руководство по установке

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Model T17 Installation Guide 43
Chapter 2. Installing the Pipe Nozzles
2.4.3 Determining and Marking the Second Nozzle Location - MR2 Mid-Radius (cont.)
2. Due to the possible variation in OD of the pipe, measure the outside diameter of the pipe at four locations
between the nozzle centers (see
Figure 54 below). Then, calculate the average OD from these measurements.
Figure 54: Multiple OD Measurements
3. Using a roll of polyester film (or equivalent), cut a strip of film with dimensions as follows:
IMPORTANT:
Ensure that the sides of the film are cut parallel to each other.
•
Example: To demonstrate the calculations, consider an
MR2
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: Width ( S ) = 2 x SQRT ((48/2)
2
- (11.81)
2
) = 41.783 in.
d. From the 3rd equation: Length (
L
) = 3.5 x 48.000 =
168.000 in.
e. Thus, one would cut a piece of film
41.783 in. Wide x 168.000 in. Long
.
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 above would be used instead.
D1
D2 D3 D4
Side View
Y
0
D 2W
–
2
-------------------
 
 
Chord Location
( ) ×
=
where, W = 0.375 inches and Chord Location = 0.5
Width S 2
D
2
----
 
 
2
Y
0
( )
2
–
×
= =
where, D Average pipe OD (see step 2)
=
Length L 3.5 D
×
= =
where, D Average pipe OD (see step 2 above)
=