Optical Scientific Inc
OFS 2000FW User’s Guide
P/N 1910-901-1
Rev. 03/28/13
12
2.5 Flange Pipe Mounting
Air infiltration through improperly sealed
flanges or from double walled stacks with
dead space between the inner and outer
walls may cause incorrect velocity readings.
Be sure that there are no openings for air to
leak into (or out of) (except for purge air
where necessary) Figures 2.4 & 2.5
illustrate the incorrect and correct methods
of installing the OFS.
Insure that the mounting pipe (nozzle) is
well sealed to the stack.
Dead space between double-walled or
stacks equipped with interior liners must be
bridged.
All gaskets and seals must be tight.
Note
– These precautions do not apply to
purge air, which is nominally under the
user’s control. Proper use of purge air is
discussed in Section 3.4
“Purge Air”.
Figure 2.4 Flange Installation - Incorrect
Figure 2.5 Flange Installation - Correct
OFS 2000 is designed to mount to the 4
– inch ANSI
150# pipe flanges commonly used in industry. The
standard dimensions are shown at right in Figure 2.6.
Note that the OSI convention is to have a bolt hole at
top dead center. The people mounting the nozzle and
flange will have to know this before they do their
installation
. (
If the bolt pattern “straddles” the
centerline, it is permissible to mount the heads tilted to
one side. The receiving lenses, must simply be rotated
a little to align with the axis of the flow stream.)
While this type is commonly used, it is not exclusive.
Flare stacks, chemical processes, hazardous
environments each have heir own unique
requirements. OSI has a range of flange adapters,
gate valves, sight glasses, spray rings, and other
items available to cope with any mounting
configuration.
Contact OSI Engineering Department regarding any
special considerations.
Figure 2.6 Common Flange Dimensions
