Diaphragm pumps play a critical role in a wide variety of industries, including chemical processing, wastewater treatment, food and beverage, pharmaceuticals, and oil and gas. These robust, versatile pumps are known for their ability to move viscous, corrosive, and shear-sensitive fluids safely and efficiently, making them indispensable for processes that require precise fluid handling. Whether transferring acids in a chemical plant, dosing chemicals in a wastewater treatment facility, or pumping slurries in oil and gas applications, diaphragm pumps offer a reliable solution where other pump types might fail.

Given the demanding environments in which diaphragm pumps operate, regular maintenance and prompt troubleshooting are essential to prevent operational disruptions and unplanned downtime. A small issue, such as a worn diaphragm or a clogged suction line, can quickly escalate into a full-scale production halt if not addressed swiftly. Proper diaphragm pump maintenance and effective troubleshooting not only extend the life of the equipment but also save on costly repairs and replacement parts over time.

Absolute Environmental understands the unique challenges associated with diaphragm pump systems and offers a comprehensive suite of services, from preventive pump maintenance to on-site diagnostics and repairs. As a trusted industry partner, Absolute Environmental provides tailored solutions and expert guidance to keep diaphragm pumps operating at peak performance, helping clients minimise downtime and maintain seamless operations.

Understanding Diaphragm Pumps

What Are Diaphragm Pumps?

Diaphragm pumps operate by flexing a flexible membrane—known as the diaphragm—to create a reciprocating pumping action. On the intake stroke, the diaphragm moves away from the pump head, creating a vacuum that draws fluid into the pump chamber through a check valve. On the discharge stroke, the diaphragm pushes fluid out through a second check valve. Check valves ensure unidirectional flow, preventing backflow and maintaining consistent pressure.

Two primary types of diaphragm pumps are commonly used in industrial applications: air-operated double diaphragm (AODD) pumps and mechanical diaphragm pumps. AODD pumps use compressed air as the power source to drive two diaphragms in an alternating motion. These pumps are prized for their self-priming capabilities, dry-run protection, and ability to handle abrasive or shear-sensitive fluids. Mechanical diaphragm pumps, on the other hand, rely on a crankshaft or eccentric mechanism to move the diaphragm. These can provide smoother flow and higher pressures but often require more complex maintenance procedures.

Common Applications

Diaphragm pumps are highly versatile and find applications across numerous industries due to their ability to handle a wide range of fluids, including corrosive acids, viscous slurries, and sanitary products. In chemical processing, diaphragm pumps transfer aggressive chemicals acid or caustic solutions with minimal risk of leakage. In wastewater treatment, they are used for dosing flocculants, polymers, and disinfectants, where precise flow control is crucial.

The food and beverage industry also benefits from diaphragm pump reliability, using them for pumping viscous liquids like syrups, sauces, and dairy products while maintaining sanitary standards. In pharmaceuticals, diaphragm pumps handle sterile and shear-sensitive fluids without compromising product quality. Meanwhile, the oil and gas sector relies on diaphragm pumps for transferring drilling mud, crude oil, and other challenging fluids. Their ability to operate in harsh conditions, including high temperatures and abrasive environments, makes diaphragm pumps a trusted choice for critical pumping tasks.

Common Diaphragm Pump Issues and Solutions

1. Pump Not Starting

Potential Causes:

• Insufficient air pressure or flow. AODD pumps require a specific range of air pressure and flow to operate. If air supply is inadequate, the diaphragms will not cycle properly, causing the pump to stall.
• Blocked air supply or muffler. Debris or buildup in the air inlet, filter, or muffler can restrict airflow, preventing diaphragm movement.
• Stuck or damaged air valve. The air valve controls the switching of air between the two diaphragms. If it becomes stuck or damaged, the diaphragms cannot oscillate.
• Diaphragm rupture. A torn or punctured diaphragm will not generate suction or discharge pressure, effectively stopping the pump.

Troubleshooting Steps:

1. Check and adjust air pressure. Verify that the filter-regulator is set to the manufacturer’s recommended pressure range. For most AODD pumps, this is between 60–100 psi. Use a calibrated gauge to confirm pressure and adjust accordingly.
2. Inspect and clean air supply lines and muffler. Disconnect the air line and inspect for blockages, moisture, or oil buildup. Clean or replace the muffler if clogged. Ensure the air supply is free of contaminants.
3. Disassemble and inspect the air valve. Remove the air valve components and check for debris, corrosion, or wear. Clean internal passages and replace O-rings or seals if damaged. Reassemble the valve and test for smooth operation.
4. Replace damaged diaphragms. Remove the pump housing and inspect both diaphragms for tears, holes, or deformation. If any imperfections are found, replace the diaphragms with manufacturer-approved parts, ensuring proper installation and torque specifications.

By systematically checking the air supply, valve components, and diaphragms, most causes of a pump not starting can be identified and resolved quickly.

2. Irregular or Erratic Operation 

Potential Causes:

• Air leaks in the suction line. Any leak in the suction plumbing will cause the pump to lose prime intermittently, leading to uneven operation.
• Worn or damaged check valves. Check valves that fail to seat properly will allow fluid to backflow during operation, disrupting the pumping cycle.
• Contaminated air supply. Moisture, oil, or particulates in the compressed air can cause the air valve to malfunction, leading to erratic diaphragm movement.

Troubleshooting Steps:

1. Inspect suction lines for leaks. Perform a suction line inspection by pressurising the intake plumbing with clean air or a mild vacuum. Listen and feel for leaks around fittings and hoses. Tighten or replace fittings as necessary.
2. Examine check valves. Disassemble the pump and remove the check valves. Inspect valve seats, balls, or flapper mechanisms for wear, cracks, or buildup. Clean valve components and replace any worn parts, ensuring that the new valves seal tightly.
3. Ensure clean, dry air supply. Check the condition of the airline filter and lubricator. Install or service existing air filters and dryers to remove moisture and particulates. Consider adding an additional inline filter if the air supply is particularly dirty.

After addressing potential air leaks and ensuring check valves function properly, the diaphragm pump should return to smooth, consistent operation without irregular or erratic cycling.

3. Low Flow Rate or Pressure 

Potential Causes:

• Clogged suction or discharge lines. Debris, scale, or sediment can accumulate in the plumbing, restricting fluid flow and reducing output.
• Worn diaphragms or valve balls. Diaphragms that have become thin or hardened lose their flexibility, while worn valve balls or seats compromise sealing, both reducing pump efficiency.
• Air supply issues. Insufficient air pressure or restricted flow can reduce diaphragm stroke amplitude, resulting in lower flow rates and pressures.

Troubleshooting Steps:

1. Clean or replace clogged lines. Disconnect the suction and discharge hoses and inspect for blockages. Flush the lines with a suitable cleaning solution or replace them if they are severely obstructed.
2. Inspect diaphragms and valves. Remove the pump head and examine diaphragm thickness, flexibility, and surface condition. Replace diaphragms that show signs of wear, cracking, or stiffening. Check valve balls and seats for pitting or damage, replacing worn components.
3. Verify air supply performance. Use a flow meter to confirm that the air supply meets the pump’s required volume (CFM) and pressure. If the supply is marginal, consider upgrading compressors or increasing pipe diameter to reduce pressure drop.

By eliminating restrictions in the fluid lines and ensuring that internal pump components are in good condition, diaphragm pumps can maintain optimal flow rates and pressures, effectively meeting process demands.

4. Excessive Noise or Vibration 

Potential Causes:

• Loose components or mounting. Bolts, clamps, or support brackets that have loosened over time can allow excessive movement and noise.
• Cavitation due to high suction lift or clogged inlet. When vapour bubbles form in the fluid being pumped and collapse rapidly, they create a distinct rattling noise and can damage the pump.
• Improperly set pulsation dampener. If a pulsation dampener is used but not adjusted correctly, the resulting pressure fluctuations can cause vibration and noise.

Troubleshooting Steps:

1. Tighten all pump components. Inspect mounting brackets, foot bolts, and clamp rings for looseness. Torque hardware to manufacturer specifications to eliminate unwanted movement.
2. Reduce suction lift and clean inlet filters. Lower the vertical distance between the pump and fluid source, if possible, to reduce the risk of cavitation. Inspect and replace clogged inlet strainers or filters to ensure a smooth flow of liquid into the pump.
3. Check and adjust the pulsation dampener. For systems equipped with a dampener, measure the air charge (if it’s an air-over-oil design) or verify spring pre-charge pressure. Adjust to the manufacturer’s recommended setting to dampen pulsations effectively.

Addressing mechanical looseness, preventing cavitation, and ensuring proper dampening will significantly reduce pump vibration and noise, leading to quieter and more reliable operation.

5. Fluid Leaks 

Potential Causes:

• Damaged diaphragms or seals. Diaphragm failures often result in fluid seeping past the pump housing. Over time, repeated flexing can weaken diaphragms, leading to cracks.
• Loose bolts or fittings. Vibration or thermal cycling can cause fasteners to loosen, creating gaps where fluid can escape.
• Cracked pump housing. Impact damage, corrosion, or extreme pressure spikes can cause the pump casing to crack, leading to visible leaks.

Troubleshooting Steps:

1. Replace damaged diaphragms and seals. Inspect diaphragms at regular intervals for signs of thinning, blistering, or cracking. Replace them immediately when damage is detected. Also, check shaft seals, O-rings, and gaskets, replacing any that show wear.
2. Torque bolts to manufacturer specifications. Refer to the pump manual for correct torque values, and use a calibrated torque wrench to tighten all housing bolts and manifold connections.
3. Inspect pump housing for cracks. Perform a visual inspection of the pump body for hairline cracks, corrosion pits, or other structural defects. If a crack is found, the housing should be replaced to maintain integrity and prevent further leaks.

By addressing diaphragm integrity, fastening hardware, and pump housing condition, fluid leaks can be minimised, safeguarding workplace safety and preventing fluid waste.

Preventive Maintenance Best Practices

Regular Inspection

Implement a routine inspection schedule to check key wear components such as diaphragms, valve balls, seats, and seals. Visual inspections should be conducted weekly or monthly, depending on the application severity. Look for signs of fatigue, cracks, or deformation on diaphragms and check valves for wear or buildup. Inspect suction line connections and discharge fittings for tightness and signs of leakage. Document each inspection in a maintenance log to track component life cycles and identify trending issues early.

Proper Lubrication

Although diaphragm pumps—especially AODD models—are air-driven and do not require lubrication in the fluid path, mechanical diaphragm pumps often have bearings and crankshafts that need regular lubrication. Use only manufacturer-approved lubricants and adhere to the recommended lubrication intervals. For air-operated pumps, ensure that the pneumatic components are properly lubricated with an inline oiler when specified by the pump manufacturer. Proper lubrication reduces friction, minimises wear, and improves overall pump efficiency.

Air Supply Maintenance

A clean, dry air supply is essential to prevent issues such as air valve sticking or contamination of internal pump components. Install high-quality air filters, regulators, and lubricators (FRLs) at the compressor outlet. Check and replace airline filters regularly to remove moisture, oil, and particulates. If the compressed air system is prone to moisture, consider adding an air dryer to keep humidity out of the pump’s pneumatic system. Contaminated air can lead to premature wear, erratic operation, and shortened diaphragm life.

Component Replacement

Follow manufacturer guidelines for replacing diaphragms and other wear parts before they reach the end of their service life. Even if components appear functional, proactively changing diaphragms every 3–6 months, or sooner for high-abrasion applications, reduces the risk of sudden failures. Likewise, replace check valves and seals according to the recommended intervals to maintain optimal pump cavitation performance and minimise fluid leak detection issues.

Training and Documentation

Empower maintenance personnel with specialised training on diaphragm pump troubleshooting and preventive pump maintenance. Create detailed maintenance procedures and checklists, covering tasks such as suction line inspection, air valve diagnostics, and pump vibration causes. Keep all documentation—manuals, inspection records, repair logs—in a centralised system to facilitate knowledge sharing and trend analysis. Well-documented processes and skilled technicians are the cornerstone of a proactive maintenance program.

How Absolute Environmental Can Assist 

Absolute Environmental offers comprehensive services tailored to diaphragm pump systems, ensuring clients benefit from expert AODD pump troubleshooting and preventive strategies. Our team of certified technicians conducts professional troubleshooting and diagnostics, pinpointing issues such as air valve issues, pump vibration causes, or fluid leak detection quickly and accurately. We maintain a robust inventory of high-quality replacement parts, including diaphragms, valve balls, and seals, enabling swift on-site repairs that minimise downtime.

In addition to reactive services, Absolute Environmental designs customised maintenance programs that align with each client’s operational demands. From routine suction line inspection checklists to scheduled diaphragm replacement plans, we provide detailed preventive pump maintenance guides to extend equipment lifespan and improve reliability. Our technical support and on-site training ensure your maintenance teams understand best practices in diaphragm replacement, pump cavitation prevention, and overall system optimisation, backed by Absolute Environmental services that prioritise your success.

Conclusion 

Regular maintenance and prompt troubleshooting are essential to ensuring diaphragm pump reliability across various industries. By following structured inspection schedules, maintaining a clean air supply, and replacing wear components like diaphragms, check valves, and seals according to manufacturer guidelines, operators can prevent common issues such as pump cavitation, air valve issues, and fluid leaks. Addressing irregular operation, low flow rate, or excessive noise early helps avoid costly downtime and preserves system integrity.

Implementing the best practices outlined—ranging from suction line inspection to proactive diaphragm replacement—empowers maintenance teams to keep diaphragm pumps performing at peak levels. Should challenges arise, Absolute Environmental is ready to provide expert guidance, high-quality replacement parts, and customised preventive pump maintenance programs. Contact us today to learn how Absolute Environmental can support your diaphragm pump systems, enhancing operational efficiency and extending equipment life.