In plastic pumps all wetted parts are plastic material. Shaft, pedestals ans other non-wetted parts may be in metal or other appropriate material. Plastic pumps are designed to move fluids that would corrode or damage other types of pumps. They provide broad chemical resistance and are less costly and lighter in weight than metal pumps. Disadvantages of plastic pumps include limited pressure ratings, reduced impact resistance, and narrower temperature ranges. Some plastic pumps are designed to move abrasive materials, acids, adhesives, chemicals, coolants, hazardous materials, lubricants. Other devices are rated for combustible, corrosive, high viscosity, or high temperature media. Plastic pumps are also used to move gasoline, diesel fuel, and oil; ground water, potable water, salt water, and wastewater; sewage, sludge, slurry and ash slurry; gas and air; powders, solids, and rendering wastes; and a variety of liquids and liquids with solids.