Are you experiencing pump cavitation when working with an Eldex Optos Series reciprocating piston pump? Cavitation is the phenomenon in which the static pressure of a liquid reduces to below the liquid’s vapor pressure, creating air bubbles.
Pump cavitation is one of the most common—and misunderstood—causes of performance problems in precision fluid delivery systems. If you’re using an Eldex Optos Series Piston Pump, understanding cavitation is essential to protecting your pump, maintaining flow accuracy, and avoiding costly downtime.
What Is Pump Cavitation?
Cavitation occurs when the pressure at the pump inlet drops below the liquid’s vapor pressure, leading to the formation of vapor bubbles. As these bubbles travel into higher-pressure regions inside the pump head, they collapse violently, generating shockwaves that can damage internal components and disrupt flow consistency.
In high-precision piston pumps like the Eldex Optos Series, even minor cavitation can significantly affect flow rate accuracy and precision, and cause unwanted pulsation.
Why Cavitation Matters in a Piston Pump
The Eldex Optos Series Piston Pump is commonly used in analytical, laboratory, and industrial applications where flow stability and repeatability are critical. Cavitation in this context can lead to:
- Loss of prime
- Erratic flow rates
- Pressure fluctuations
- Increased check valve wear
- Seal damage
- Excessive noise or vibration
Because piston pumps operate with rapid suction and discharge cycles, they are especially sensitive to insufficient inlet pressure or restricted suction lines.
Common Causes of Cavitation in the Eldex Optos Series
Inadequate Net Positive Suction Head (NPSH)
If the available suction pressure (NPSHa) is too low, vapor bubbles form during the intake stroke. This is often caused by:
- Long or narrow inlet tubing
- High flow rates
- Elevated fluid temperatures
- Low reservoir height relative to the pump
Suction Line Restrictions
Clogged inlet filters, partially closed valves, or undersized tubing increase suction losses and promote cavitation.
High Fluid Temperature
Warmer liquids have higher vapor pressures, meaning they cavitate more easily. Temperature control becomes especially important in solvent-based applications.
Entrained Air
Air leaks in fittings or degassing issues can mimic or worsen cavitation symptoms. Degas the fluid before use by boiling, sparging with helium (bubbling), or placing it under vacuum.
Signs You May Have Cavitation
With the Eldex Optos Series Piston Pump, watch for:
- Sudden drop in discharge pressure
- Visible microbubbles in tubing
- Inconsistent flow readings
- Unusual clicking or rattling sounds from the pump head
- Premature check valve failure
In analytical systems, cavitation often first manifests as unstable baselines or reproducibility issues.
How to Prevent Cavitation
Optimize Inlet Conditions
- Use short, large-diameter suction tubing
- Keep the reservoir level above the pump inlet when possible
- Minimize fittings and bends
- Ensure inlet filters are clean
Control Fluid Temperature
Lowering fluid temperature reduces vapor pressure and the risk of cavitation.
Improve Degassing
Proper solvent degassing—via vacuum, helium sparging, or inline degassers—helps eliminate dissolved gases that contribute to bubble formation.
Reduce the Speed of Refill Rate
Eldex pump menu settings let you slow down the “rapid-retract” function. Refill rate is the rate of piston retraction during the pump refill stroke. Full Out refers to a maximum speed refill designed to minimize pulsation. With DI water in particular, this rapid refill can pull gas out of the fluid, leading to bubbles in the plumbing and pump cavitation. By adjusting the refill rate (i.e., the % of time spent in the pumping stroke vs. refill stroke), the rapid refill can be slowed down – hopefully preventing this degassing. i.e., 50/50 refers to balanced pump cycle times – 50% pump stroke, 50% refill.
Final Thoughts
The Eldex Optos Series Piston Pump is engineered for high precision and reliability—but like any piston-driven metering pump, it relies heavily on proper inlet conditions. Cavitation is not just a mechanical issue; it’s a system-level problem that often stems from suction design, temperature, or fluid-handling practices.
By proactively optimizing your inlet setup and monitoring early warning signs, you can maintain the pump’s accuracy, extend component life, and ensure consistent performance across demanding applications.
If you’re troubleshooting flow instability, start at the inlet—cavitation may be the hidden culprit.
Learn more about Eldex Optos Series Pumps.
