26
Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit
armstrong
international.com for up-to-date information.
Installation Overview – continued
Installing Flow Meters with a Packing Gland Connection*
Use the formula below to determine the insertion depth for flow me-ters (NPT and flanged) equipped with an insertion
tool. To install, see the next page for instructions for meters with a permanent insertion tool. For meters with a
removable insertion tool, see page 27.
Where:
I = Insertion length.
F = Distance from the raised face of the flange or top of the process
connection for NPT style meters to the top outside of the process pipe.
R = Pipe inside diameter, divide by 2 for pipes ten inches & smaller.
R = Five inches for pipe diameters larger than ten inches.
t = Thickness of the pipe wall. (Measure the disk cutout from the tapping
procedure or check a piping handbook for thickness.)
Example 1: Flange Style Meters:
To install an AVI Flow Meter into a 14 inch schedule 40 pipe, the following measurements are taken:
F
=
12
inches
R
=
5
inches
t
=
0.438
inches
The example insertion length is 16.09 inches.
Example 2: NPT Style Meters:
The length of thread engagement on the NPT style meters is also subtracted in the equation. The length of the threaded
portion of the NPT meter is 1.18 inches. Measure the thread portion still showing after the installation and subtract that
amount from 1.18 inches. This gives you the thread engagement length. If this cannot be measured use .55 inch for this
amount.
F
=
12
inches
R
=
5
inches
t
=
0.438
inches
The example insertion length is 15.54 inches.
*All dimensions are in inches
Figure 2-8. Insertion Calculation (Meters with Insertion Tool)
Insertion Length Formula
I = F + R + t – 1.35
I
R
t
F