Sometimes pump performance problems do not start at the pump. Rather, they start at the spec sheet, with the wrong pump picked for the job or the right pump set up the wrong way. In a recent webinar, Caleb Summers, Lead Application Engineer at Unibloc® Hygienic Technologies, discussed where air-operated double-diaphragm (AODD) pumps perform best in a hygienic process and what newer pump designs have changed about the conversation. Here are six reasons to consider one for your application.
1. AODD pumps run dry and deadhead without damage
Most pumps rely on the product to lubricate and cool the shaft seal. Run them dry, and the seal heats up and fails. Deadhead them against a closed valve and pressure builds until something gives. AODD pumps have no rotating shaft and no shaft seal. When discharge pressure equals the driving air pressure, the pump simply stops. Open the downstream valve, and it starts again. For transfer-to-hopper or batch-fill setups, deadheading changes from a failure mode into a control method.
2. AODD pumps self-prime and lift product from drums and totes
AODD pumps pull roughly 13 feet of dry suction lift and close to 26 feet wet. That matters in any plant pumping out of 55-gallon drums or IBC totes. A specification tip: when suction is the bottleneck, increase the size of the suction pipework before installing a larger pump. AODD pumps can have different inlet and discharge port sizes, so optimal performance does not require oversizing the whole unit.
3. AODD pumps do not damage high viscosity fluids or solids
Large internal clearances and a low-shear flow path let the pump pass solids without damaging them, which is ideal for applications such as diced tomatoes, chocolate with whole almonds, and pre-cooked lentil curries that need to be pumped without damage. Standalone AODD pumps move viscosities up to 100,000 cP. Or, when paired with a drum unloader, the range extends past 500,000 cP. As one example, a manufacturer uses a Flotronic® AODD barrel-unloading system to move 500,000-cP medical-grade silicone from drums into mixing vessels.
4. The same AODD pump can push water and tomato paste
AODD pumps move products from 1 cP to 300,000 cP without the need to change motors or add gear reducers. Lobe, gear, and twin screw pumps deliver smoother flow at high pressure, but each is specified for a narrower viscosity window.
That broader range was perfect for a global personal-care manufacturer that was contracted to process a varied line of hygienic products. Process engineers there chose AODD pumps specifically because operators never knew which product they would be running next. The pump handled products throughout the full viscosity range, switched between products without intervention, and allowed a CIP cycle in between.
5. AODD pumps are intrinsically safe in hazardous areas
Air power eliminates the electrical ignition source. There is no ATEX-rated motor to worry about, no class-and-division motor, and no special wiring. The seal-less design also matters with aggressive acids and caustic chemicals, where a leak in a shaft seal is a potentially dangerous condition.
In one application, a packaging producer pumping flammable solvents bought multiple AODD pumps, mounted them at waist height for fast access, and built a maintenance program around how easy the pumps are to disassemble and service.
6. More advanced AODD designs cut cleaning from hours to minutes
The major limitation of conventional AODD pumps is cleaning time. A traditional, standard AODD design involves side pipework and perhaps 20 to 30 bolts that need to be removed for every sanitation cycle, turning changeover into what becomes a two-hour COP job for every AODD pump in the plant. Inlet pressure capped near 10 psi also blocks the opportunity for CIP.
Flotronic® engineers, however, created an AODD+™ design, a unique patented approach that cuts cleaning time and complexity with a novel one-nut solution. By routing product through the center of the pump, moving the diaphragms outside, and clamping the assembly with one nut and far fewer parts, the Flotronic AODD+ unit can be disassembled, cleaned and reassembled in 15 minutes. Optional reinforced diaphragm support plates accept up to 7 bar (100 psi) at the inlet, making the pump part of the CIP loop instead of an obstacle bypassed with valves.
Consider what that means for one cosmetic plant running 20 AODD pumps. With its product priced up to $170 an ounce, the Flotronic One-Nut® design shortened cleaning times to just 15 minutes per pump and reduced product hold-up by up to 60%.
Traditional AODD vs AODD+?
Keep hygienic lines up and running and high-value product from being damaged. Learn more about when AODD pumps are applicable and how they can benefit your process by watching the full webinar: When to Use an AODD Pump: Applications, Design & Considerations.
