Diaphragm Metering Pumps
Diaphragm metering pumps employ flexible membranes to alter the volume of a controlled chamber in order to effectively displace fluids with accuracy and precision. Like all metering pumps, diaphragm models are utilized in many industrial and commercial applications. They are lauded for their ability to provide consistent fluid input to maintain a homogenous process flow, even through continuous use. With extremely high accuracy rates, exact amounts of liquid are pumped at predetermined intervals.
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Applications of Diaphragm Metering Pumps
This particular type of metering equipment is utilized in the daily operations of aerospace, marine, food and beverage processing, chemical, electronic, mining, petrochemical, material handling and transport, medical, construction, automotive, and agricultural industries. The immense capabilities of these liquid meters is demonstrated by their ability to transport thousands of gallons of crude oil and fuel, while their precision is illustrated by their use in artificial hearts.
Characteristics of Diaphragm Metering Pumps
Compressed air is used to stretch the membrane in pneumatic pumps, while other models employ a rod, piston, or other mechanical device attached to the center of the film in order to push or pull it and change the volume of the adjacent chamber. Hydraulics may also be used and act similar to pneumatics but with the use of hydraulic fluid rather than air. No matter the actuator, the diaphragm pump is popular because it is low maintenance, has few moving parts, and is less prone to leaks than piston metering pumps due to the lack of seals, which are most often the source of leaks due to repeated friction and wear over time.
Diaphragm Metering Pump Design
The diaphragm pump is relatively simple in design, making it highly reliable. Most often, a single diaphragm is attached to the interior walls of a cylindrical chamber. Clamped or otherwise sealed, this creates an unmoving barrier between the actuating device and the fluid. At the opposite end of the cavity are inlet and outlet connections, both with check valves to ensure the proper flow directionality.
When the membrane is retracted, it increases the volume of the chamber, decreasing pressure and effectively creating a vacuum, which draws a specified amount of fluid in through the inlet valve. Alternatively, stretching the diaphragm back down towards the fluid increases pressure and pushes the liquid out through the exhaust valve. Variable materials may be used for both the membrane and the housing which keeps it in place. Additional considerations for diaphragm pumps include maximum flow, maximum pressure discharge, inlet size, exhaust size, media, operating temperature, and power source.
Materials Used in Diaphragm Metering Pumps
Materials such as aluminum, stainless steel, cast iron, brass, or bronze are used for the holder, while ethylene propylene, rubber, plastic, and other elastomers are common compositions for the membrane itself. Material selection is extremely important and must take into account the liquids that are to be pumped, as they may include waters, oils, solvents, fuel, coolant, and acids as well as other hazardous or even toxic materials. Abrasive fluids require particularly durable diaphragm construction.