Emerson Micro Motion Viscomaster Installation Manual page 10

Planning
1.4.3 Entrained gas
Entrained gas, or gas pockets, can disrupt the measurement of a fluid. A brief disruption in
the signal caused by transient gas pockets can be corrected in the meter configuration,
but you must avoid more frequent disruptions or serious gas entrainment to ensure
accurate and reliable fluid measurement.
To minimize the possibility of entrained gas:
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1.4.4 Solid contamination
To avoid issues related to solids contamination:
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1.4.5 Temperature gradients and insulation
For high-viscosity fluids, minimize any temperature gradients in the fluid, and in the piping
and fittings immediately upstream and downstream of the meter. Minimizing
temperature gradients reduces the effect of viscosity changes. Micro Motion recommends
using the following guidelines to reduce the thermal effects to your meter installation:
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Keep pipelines full of fluid at all times.
Vent any gas prior to the meter installation location.
Avoid sudden pressure drops or temperature changes that may cause dissolved
gases to break out of the fluid.
Maintain a back pressure on the system that is sufficient to prevent gas breakout.
Maintain flow velocity at the sensor within the specified limits.
Avoid sudden changes of the fluid velocity that may cause sedimentation.
Install the meter far enough downstream from any pipework configuration that may
cause centrifuging of solids (such as at a pipe bend).
Maintain flow velocity at the meter installation that is within the specified limits.
Use filtration in your process, if necessary.
Always insulate the meter and surrounding pipework thoroughly.
- Avoid insulating the transmitter housing.
- Use rock wool or any equivalent heat jacket material that is at least 1 inch (25
mm) thick, but preferably 2 inches (50 mm) thick.
- Enclose insulation in a sealed protective casing to prevent moisture ingress, air
circulation, and crushing of the insulation.
- For flow-through chamber installations, use the special insulation jacket
provided by Micro Motion.
Avoid direct heat or cold on the meter or on the associated upstream or
downstream pipe work that is likely to create temperature gradients.
If it is necessary to protect against cooling because of flow loss, you can apply
electrical-trace heating. If you use electrical-trace heating, use a thermostat that
operates below the minimum operating temperature of the system.
Micro Motion Heavy Fuel Viscosity Meter