If you use eccentric reducers, the piping must maintain 20 in (508 mm) of upstream
straight run (both sides for bidirectional flow applications) to avoid jet effect and a
resultant “spray” on the fork tines.
3.1.3 Mount in free-stream application (weldolet fitting)
The weldolet for free-stream installations has a 1.5 in (38 mm) taper lock fitting and is
supplied to be welded on 4 in (102 mm), 6 in (152 mm), 8 in (203 mm), or 10 in (254 mm)
pipelines. A weldolet installation ensures that the tines of the meter are oriented correctly
and are fully inserted into the fluid stream.
Prerequisites
• Free-stream (weldolet) installations are recommended for processes with the following
conditions:
Flow 0.3 to 0.5 m/s at the meter
Viscosity
— Up to 500 cP with long tines
— Up to 20,000 cP with short tines
Temperature -58 °F (-50.0 °C) to 392 °F (200 °C)
-40 °F (-40.0 °C) to 392 °F (200 °C) in
hazardous areas
Note
If temperature variations are a critical factor in your process, the reduced thermal mass
of the taper-lock fitting of the weldolet can track changes in temperature more
efficiently.
• Before fitting the weldolet, you must bore a 2.1 in (53 mm) diameter opening in the
pipeline to accept the meter. You must weld the weldolet to the pipeline concentrically
with the pre-bored hole.
Procedure
See Figure 3-5 for information on installing the meter (with a weldolet fitting) in a free-
stream application.
• Insert meter tines directly into the fluid flow.
• For both vertical and horizontal pipes, always install the meter on the side of the pipe.
For a horizontal pipe, never mount the meter on the top of the pipe.
Important
During installation, always position the meter so that the gap between the tines is vertical.
This position helps prevent the trapping of bubbles or solids on the meter – allowing the
solids to sink and the bubbles to rise. You can use the scribe mark on the spigot (located
between the flange and transmitter) as a reference for the tine orientation. Always orient
the meter so the scribe mark is at either the 12 o’clock or 6 o’clock position.
The gap between the fork tines must always be vertical so that:
• Solids drop down
• Entrained gas will go up
Mounting
Installation Manual
May 2019 MMI-20020989
20 Micro Motion Fork Density Meter
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