Dairies have effluent in many places. Manure pits, parlor water, effluent from settling basins and runoff are common sources. There are several things to consider when selecting a pump. One of the first is finding a pump that will handle the pressure and head from the effluent lines. The higher the elevation is that the effluent has to be pumped, the higher the head pressure.
There is also pressure from the resistance in the pipes due to friction on the pipe walls, turns in the pipe and the distance between the pump and outlet.
Pumps must be able to keep up with the inflow of effluent. Ideally, the pump is off more than it is pumping. If the pump cycle is too short, the life of the pump may be compromised.
Pump flow rate is calculated using clear water. Effluent with a thicker viscosity will be pumped at a lower flow rate.
Different effluents have different levels of solids. A liquid generally has less than 4 percent solids, a slurry has 4 to 10 percent solids, and more than 10 percent is considered semi-solid or solids. Pumps must be able to handle the level of solids in the effluent being pumped.
Pumps are available that can use different power sources. The most common is 110 volts. Larger pumps may require a higher voltage. PTO-driven pumps are often used for portable pumps. Battery backup pumps are often used in home sumps.
Maintenance of pumps should be minimal and simple. Grease ports should be easy to access and any replaceable parts such as shear pins should be easy to replace.
It is always a good policy to make sure that parts and service are readily obtainable. Buying a pump built with higher-quality parts made from brass, cast iron or gun metal is preferable to plastic or sheet metal components.
Some pumps require being primed before they will work. Generally, dairy pumps are set in the effluent and require no priming.
There are different types of pumps. Centrifugal pumps are common, as they will handle higher levels of solids such as in a slurry.
Higher pressures are attainable with an axial or helical gear pump. However, these pumps will not handle abrasive materials as they require tighter tolerances to be efficient.
Knowing what and how much you are pumping will help in selecting the correct pump to do the required task. PD
—Excerpts from 2013 Iowa Dairy Days proceedings
Dan Huyser is an ag engineering program specialist for Iowa State University Extension.
