23 JULY 2003
d. Minimum and Maximum Head. The minimum head will be based on the
specific application required. In general, a minimum positive head of 610 mm (24
inches) should be provided at the suction side of the pump, and a maximum suction lift
should not exceed 10 feet for plunger-type pumps. An additional safety factor of 10 to
25% should be applied to the dynamic pressure to reduce the effects caused by the
thixotropic characteristics of the sludge.
e. Sampling Facilities. Unless additional provisions are required, sampling
valves should be provided at the sludge pumps. The sampling valves should be quick
closing valves of at least 1 inches that terminate at a suitably sized sampling sink or
2-18.104.22.168 Sludge Piping. The following minimum sizing criteria and requirements
should be considered for sludge piping (GLUMRB 1990):
a. Size. Sludge withdrawal piping should have a minimum diameter of 150
mm (6 inches). Minimum diameters for pump discharge lines should be 100 mm (4
inches) for facilities treating less than 22 L/s (350 gpm) and 200 mm (8 inches) for
facilities treating more than 45 L/s (700 gpm). Short and straight runs are preferred, and
sharp bends and high points should be avoided. Although not recommended, if less
than 100-mm (4-inch) piping is used, additional cleanouts should be provided and no
sharp bends should be present.
b. Head. The available head for gravity withdrawal should be at least 7.5 kPa
(30 inches) or greater as necessary to maintain a 0.9-m/s (3-fps) velocity in the
c. Slopes. Gravity piping should be laid on uniform grade and alignment. The
slope for gravity piping should not be less than 3% for sludge with greater than 2%
solids and should not be less than 2% for sludge with less than 2% solids.
d. Flushing. Blank flanges and valves should also be provided for draining,
flushing, and cleanout.
e. Freeze Protection. All sludge piping should be adequately protected to
Operation Related. Sizing criteria can be related to both operation and
maintenance labor requirements and equipment requirements.
2-7.3.1 Operation and Labor Requirements. Operation and labor requirements are
important considerations in sizing equipment because the plate and frame filter press
pressure system operates in a batch mode. The effects of operation and labor
requirements on sizing equipment can best be demonstrated by the following examples.
First, if one 8-hour operating shift is desired rather than two shifts, then the dewatering
equipment for the former case would be larger unless multiple units were used. Second,