EODD vs AODD Pumps: Where the Real Running Cost Goes
For years, AODD pumps have been a popular choice across industries. They are simple, they run in hazardous areas, and they handle a wide range of liquids. But there is a side of their operating cost that often gets overlooked, because the cost does not show up on the pump. It shows up on the compressor, the spares shelf and the maintenance schedule. This page walks through where that cost sits and how an electric operated double diaphragm pump changes it.
Where does the running cost of an AODD pump actually go?
The overlooked cost of an AODD pump
- Compressed air comes at a cost.
- Diaphragm failures mean replacement costs and downtime.
- Pulsating flow creates pressure fluctuations, often requiring a pulsation dampener.
- More maintenance means more time and money spent keeping the pump running.
Where an EODD pump changes the equation
- An electric drive takes the place of compressed air.
- Longer diaphragm life, so fewer replacements and less downtime.
- More consistent flow, without the pulsation associated with AODD pumps.
- Less maintenance, with no pulsation dampener required in the applications we are targeting.
None of this makes the AODD pump a bad pump. It makes it a pump whose true cost is spread across several budgets, which is why it is easy to miss. The air bill sits with utilities, the diaphragms sit with stores, and the downtime sits with production.
What do our calculations show?
About these figures. They come from Sando's own calculations and the scenarios we have evaluated, not from a universal rating. The result for your plant depends on your duty, your running hours and what you pay for power and air.
The short version. Yes, an EODD pump costs much more upfront. But when you factor in electricity, spares, maintenance and downtime, the total cost can look very different. In over 90 percent of the scenarios we have evaluated, EODD does not just beat AODD on total cost of ownership. It beats it by a significant margin.
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Why does the gap exist in the first place?
Electricity: why compressed air costs more than it looks
An AODD pump does not run on electricity directly. A compressor first turns electricity into compressed air, the air travels through the plant piping, and only then does it move the diaphragms. Every step of that chain loses some energy, and leaks in the air network add to it. An EODD pump skips the chain. The electric motor drives the diaphragms directly, so more of the energy you pay for goes into moving liquid.
That is the reason our calculations show 20 to 40 percent lower electricity consumption. The saving is largest where the pump runs for many hours and the air system is the expensive part of the plant.
Diaphragm life: why a controlled stroke is easier on the diaphragm
In an air driven pump, the speed and force of each stroke follow the air supply, so a change in air pressure or a blocked discharge changes how hard the diaphragm works. In an electric pump, the drive mechanism sets the stroke, so the diaphragm moves through the same motion every time. A diaphragm that sees steadier loading has a better chance of lasting, and in our calculations that shows up as 30 to 40 percent longer diaphragm life.
Fewer diaphragm changes also means fewer stoppages, fewer spares to hold and less time with the pump opened up.
Pulsation: why the dampener becomes optional
Any double diaphragm pump delivers liquid in strokes, but an air driven pump also pauses and shifts as the air valve changes over. That is where the pressure swings in the discharge line come from, and why a pulsation dampener is often added. The electric drive keeps the two chambers moving in a fixed rhythm, which gives more consistent flow. In the applications we are targeting, that means no dampener is needed, one less part to buy, install and maintain.
Maintenance: fewer moving parts to look after
Less pulsation, steadier diaphragm loading and no dampener all point the same way. There are fewer reasons to open the pump, fewer fittings that can leak and fewer items on the maintenance list. If you want to see the mechanics behind this, how electric diaphragm pumps work shows the drive and the check valves, and how an AODD pump works shows the air side for comparison.
Which cost heads should you compare?
| Cost head | AODD pump | EODD pump |
|---|---|---|
| Upfront price | Lower | Much higher |
| Energy | Compressed air, with losses in the air network | Electricity, 20 to 40% lower in our calculations |
| Diaphragm life and spares | Replacement costs and downtime | 30 to 40% longer diaphragm life |
| Flow quality | Pulsating, often needs a pulsation dampener | More consistent, no dampener in the applications we target |
| Flow control | Air pressure and air volume | Motor speed and the control system |
| Maintenance effort | More time and money keeping it running | Less maintenance |
| Leakage-sensitive liquids | Diaphragm pump, no shaft seal in contact with the liquid | Sealless, electric drive |
When is an AODD pump still the right choice?
Honestly, in several situations. If you need a portable pump that can be moved between jobs, if the duty is in a hazardous area, if the pump runs only now and then, or if your plant already has plenty of spare compressed air, an AODD pump can make complete sense. The AODD specifications list flow up to 999 litres per minute, pressure up to 8 bar and suction lift up to 24 feet wet and 15 feet dry, in sizes from 1/2 to 3 inch, and the range covers both metallic and non metallic builds.
The EODD case gets stronger as running hours go up, as the duty becomes frequent or repetitive, and as consistent, repeatable flow starts to matter. Batching, metered transfer and recirculation are good examples. The EODD range comes in sizes from 1/2 to 3 inch, in PP, PVDF, SS316, SS316L, aluminium, conductive PP, conductive PVDF and super duplex.
How do you compare the numbers for your own plant?
Tick these off as you gather them. They are the inputs that decide whether the lower running cost of an EODD pump covers the higher purchase price.
If you are still choosing a pump type, the pump selector and the pump selection manual help narrow it down by application, and the EODD product page shows the build options.
Frequently asked questions
Is an EODD pump cheaper than an AODD pump?
Not at purchase. An EODD pump costs much more upfront. The comparison that matters is total cost of ownership, which includes electricity, spares, maintenance and downtime. In over 90 percent of the scenarios we have evaluated, EODD comes out ahead on that measure.
How much electricity can an EODD pump save compared with an AODD pump?
Our calculations show 20 to 40 percent lower electricity consumption. The actual figure depends on running hours, duty and the efficiency of your compressed air system.
Does an EODD pump need a pulsation dampener?
In the applications we are targeting, no. The electric drive gives more consistent flow, without the pulsation associated with AODD pumps, so a dampener is not required.
Does an EODD pump make diaphragms last longer?
Our calculations show 30 to 40 percent longer diaphragm life, because the electric drive moves the diaphragm through a controlled stroke instead of following the air supply.
When should I stay with an AODD pump?
When you need a portable pump, when the duty is in a hazardous area, when the pump runs only occasionally, or when your plant has plenty of compressed air available.
Still running AODD pumps? Let us compare the numbers for your plant
At Sando Rotary Equipments, we have spent the last 5 to 6 years developing our EODD technology. If you are still running AODD pumps, share your application and we will go through the calculations with you directly. You might be surprised by what you are paying to save.
Sando Editorial Team
The Sando Editorial Team consists of pump technology experts and engineers at Sando Rotary Equipments, dedicated to sharing insights and innovations in the fluid handling industry.
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