Yes, AODD diaphragm pumps can cavitate under certain conditions. Cavitation occurs when the pressure in the pump falls below the vapor pressure of the liquid being pumped, causing vapor bubbles (or cavities) to form. These vapor bubbles are then carried into the higher-pressure regions of the pump, where they can collapse or implode, leading to noise, vibration, flow deficiency and potential damage to the pump components.
Damage to AODD pumps is usually less severe and costly compared to other types of pumps, primarily affecting diaphragms with occasional issues involving valves or the pump body. However, cavitation in AODD pumps can significantly increase operational costs.
Here are some common causes and preventive measures to avoid cavitation in AODD pumps:
Common Causes of Cavitation in AODD Diaphragm Pumps
Inadequate Net Positive Suction Head (NPSH): If the Net Positive Suction Head Available (NPSHa) is less than the Net Positive Suction Head Required (NPSHr) by the pump, cavitation can occur. NPSHr is provided by the pump manufacturer and should always be met or exceeded by the system’s NPSHa.
High Suction Lift: Excessive suction lift (the vertical distance between the pump and the fluid source) can reduce the pressure at the pump inlet, leading to cavitation.
Long or Restrictive Suction Piping: Long suction lines, sharp angles, undersized piping or too many fittings and valves can create friction losses, reducing the pressure at the pump inlet. Suction pipe should always be the same size or larger than the pump’s suction port. Suction filters should be un-restricted and inspected periodically.
High Fluid Temperature: Higher fluid temperatures increase the vapor pressure of the liquid, making it easier for cavitation to occur.
Viscous or Entrained Solids: Pumping highly viscous fluids or fluids with entrained solids can increase the suction pressure requirements and lead to cavitation if not properly managed.
Preventive Measures
Ensure Adequate NPSH: Verify that the NPSHa in your system meets or exceeds the NPSHr specified by the pump manufacturer. This can involve checking the system design and making necessary adjustments.
Optimize Suction Piping: Use appropriately sized suction piping, suction pipe should always be the same size or larger than the pump’s suction port.  Minimize the length of the suction line, and reduce the number of fittings and valves to minimize friction losses.
Control Fluid Temperature: Maintain the fluid at a temperature that keeps its vapor pressure low, reducing the risk of cavitation.
Proper Pump Placement:Â Position the pump as close to the fluid source as possible to minimize suction lift and friction losses.
Regular Maintenance: Ensure the pump and suction line are free of blockages and that the pump components are in good condition to maintain optimal performance.
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