Air operated double diaphragm pumps (AODD) operate with compressed air instead of an electric motor. This makes them much safer for many types of applications, particularly those that require pumping flammable liquids.
AODD Proper Pump Installation is Important
AODD pumps must be installed properly with correct mounting on a rigid base plate, the fluid inlet suction hose or pipe must not ever be smaller than the suction port size in diameter. The air supply line must be correctly sized, and an air pressure regulator should be installed in the pump’s air supply line to control incoming air pressure. If operating AODD pumps is something new to you, consult with a pump and process equipment specialist to ensure proper setup and installation.
Troubleshooting AODD Pumps
If your AODD pump experiences failure or poor performance, there are a number of things you can try to resolve the problem. Here is a list of problems and remedies for AODD pump failures:
- Air valve leaking, stalling, or clogged – If the air valve seems to be stalling or leaking, the design of the airways could be less than optimal. If it seems to be clogged, this could be due to the quality of air in use. Be sure to use filtered air.
- Rupture of the diaphragm – The AODD diaphragm is always subject to mechanical stress and may experience stress cracks over time which lead to failure. The manufacturing method, along with the diaphragm material, plays an important role in how long the diaphragm will last. Pressure is another important factor, as higher stress is placed on the diaphragm with higher pressure. The number of strokes will greatly affect the life of the diaphragm as faster-running pumps will fail more quickly.
- Muffler clogging or icing – the moisture content in the air is the main reason for muffler icing as it will condense with a drop in temperature and air pressure. Be sure to use clean, dry, filtered air and make sure no debris has been collected over time.
- Check valve failure – ball-style check valves are typically used in AODD pumps which can fail if something gets in between the ball and the seat to prevent a leakproof valve closure. A strainer can reduce this occurrence. If you suspect something is stuck, flushing the pump can often clear debris. Wear of the ball and seat can also cause leaks due to abrasive particles or choice of material.
- Torque settings – AODD pumps can experience violent and consistent stroke impact, which can over time, loosen bolts which reduces pump pressure. Retightening the bolts periodically helps to make sure the sealing surfaces stay sealed. If using plastic pumps, reinforcement with metallic plates is recommended as molded plastic is softer and can warp with internal stress.
- Pump won’t run – if your pump does not run, it could be due to a number of circumstances such as:
- Air pressure is too low – the air pressure supply must be greater than 1.2 bar and the system pressure.
- Solids in the pump chamber – solids can block the diaphragms from moving if they settle in the pump chamber and prevent pump operation. Solid particles can prevent the ball valves from properly reseating and cause the pump to not work.
- Blocked exhaust or muffler – this prevents the pump from efficiently expelling air and can directly affect the ability of the diaphragm pump to operate. Make sure there are no obstructions blocking the exhaust, and ensure the muffler is in good working condition.
These are just some of the most common problems that can occur when operating an AODD pump. Illinois Process Equipment, IPE, offers pump and process equipment solutions, including troubleshooting and service for AODD pumps.
IPE is a leading Midwest pump and process equipment supplier, set apart from other pump suppliers with our level of technical expertise and responsiveness to our customer needs. We offer high-quality pumps from top brands and comprehensive services, including complete process system design, installation, testing, and service. Contact us with any questions and for assistance in troubleshooting AODD pumps.