Example 13.1 Estimate the grit channel length necessary if the maximum depth of flow in the channel is likely to be 1.7 m. Assume grit settling velocity = 10 cm/s, and horizontal flow velocity = 30 cm/s. Use scale-up factor = 5.0.

Also, a check valve should not be located immediately downstream of a source of turbulence, such as a pump, elbow, control valve, or a tee-branch connection. It is recommended that manufacturer’s recommendations be followed to provide the required straight run of pipe upstream of the check valve. Some manufacturers recommend 8-to-10 pipe-diameter length of straight run of pipe upstream of the valve. Sometimes, the layout and the space available may not allow compliance to manufacturer’s recommendations. Alternatives must be evaluated and the most reasonable and feasible approach be implemented.

In other cases, where guards are impractical and insulation is more appropriate, the insulation is applied only to the piping that is within 7 ft (2.1 m) of the ground or platform in high risk areas.