One of the main disadvantages of standard solids handling pumps is that there is a nominal solids passing diameter. The pumps, depending on their size, can only pass solids that are smaller than the intake of the volute and piping. If a larger solid tries to pass, it can potentially block the pump. Another problem with solids handling pumps is that they are dependent on the force main size and its ability to pass the same solid that the pump can pass. There is a chance of clogging the pump if the pump can pass a larger solid than what the force main can handle. Solids hand pumps are also dependent on the flow rate. The size of the force main and flow rate dictate what pump will be picked in a design by determining the total dynamic head of the system. Solids handling pumps are not good in low flow, low head conditions. Often the design flow has to be higher than the peak flow to create extra head so a pump can be selected. Additionally, solids handling pumps are not good in low flow, high head conditions, and finding a pump is difficult. Lastly, not all solids handling pumps are available with an explosion proof (FM) rating. This rating can be crucial in wastewater applications if the area is designated as class 1, division 1.