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Chemical and Process Engineering Resources

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Category: Equipment Design
Question: Are there flow velocity restrictions to avoid static charge build up in pipelines?
Keywords: v1i4,flow,velocity,restrictions,methanol,pipeline,static,charge
Answer: There's an Australian standard "AS1020 (1984) - Control of undesirable Static Electricity"In it theres a table for flammable hydrocarbons as follows:
Pipe Size (mm) Max Velocity (m/s)
10 8
25 4.9
50 3.5
100 2.5
200 1.8
400 1.3
600+ 1.0
This is based on pure hydrocarbons, and there is a correction that can be applied for fluids of different conductivity (resistivity). Methanol has a higher polarity than hydrocarbons and hence is more conductive. The resistivity of diesel is 1013 ohm-m vs 108 for methanol.In addition to this, normal piping design guidelines should however be followed, such as appropriate earthing, and ensuring exit velocities into tanks of 1 m/s.