TPS 2025: Sealless Pumps Offer Safer, Cleaner Option for Ammonia Systems

Ammonia has been a long-standing cornerstone in agriculture, manufacturing, and the clean-energy transition, but its hazardous properties are driving demand for safer and more reliable pumping technologies. August Brautigam, Pump Development Engineer at Ebara Elliott Energy, addressed the benefits of sealless pumps—including magnetic drive and canned motor designs—at the 2025 Turbomachinery & Pump Symposia.

While its versatility makes ammonia valuable, Brautigam said that handling the liquid poses safety risks. Ammonia is toxic, corrosive, and class-2 flammable. It dissolves copper, requires water mixing to reduce stress corrosion cracking of carbon steel, and can create operational hazards if not properly contained. Cavitation—the formation of vapor bubbles in the fluid—can also occur.

Why Sealless Pumps?

Sealless pump technology provides several advantages in this environment. Unlike pumps with mechanical seals, magnetic drive and canned motor pumps eliminate external leakage points, one of the most common failure points in traditional designs. The density difference between liquid and gaseous ammonia further highlights the importance of robust equipment, as liquid ammonia is 950 times denser than its gas form, meaning even small leaks or seal failures could have serious operational and safety consequences.

Magnetically driven pumps offer several advantages that make them especially well-suited for ammonia applications. Their most important benefit is leak-free operation, since the magnetic coupling eliminates the need for mechanical seals. This ensures ammonia, which is both toxic and corrosive, is safely contained and prevents fugitive emissions that could pose risks to workers and the environment. By design, mag-drive pumps also require less maintenance because there are fewer wear components, lowering costs and reducing downtime in continuous operations like fertilizer production or ammonia co-firing plants.

Their compact footprint makes them easier to integrate into storage, transfer, and processing systems, while their efficiency and compatibility with variable frequency drives allow operators to manage energy use more effectively. Together, these features make magnetically driven pumps a safe, reliable, and efficient choice for ammonia service, particularly in industries where environmental compliance and operational reliability are critical.

Leak-free canned motor pump for liquid ammonia | Image Credit: Ebara Corp.

Additionally, canned motor pumps provide smooth, reliable operation and can handle ammonia at varying pressures and temperatures without compromising efficiency. Their compact, integrated design further allows for space savings and simplified installation, making them particularly well-suited for ammonia storage, transfer, and industrial processing applications where safety, reliability, and low maintenance are critical.

Both designs remove the need for seal flush systems, reduce maintenance demands, and most importantly, prevent leakage. Variable frequency drives are often paired with these pumps to adapt to fluctuating load conditions. Brautigam noted that magnetic couplings can be sized based on motor full-load torque, ensuring pumps handle ammonia’s demanding characteristics reliably.

Technical Considerations

Engineers designing ammonia pumping systems face several challenges, from cavitation risks to material selection. Cavitation requires significant energy to occur with ammonia, making it less frequent than in water systems. Still, operators must account for the phenomenon in pump sizing and operation.

To validate performance, many ammonia pumps are tested with propane due to its similar fluid properties but lower handling risks. Once qualified, sealless pumps used in ammonia service are often designed as multistage barrel magnetic drive pumps or multistage barrel canned motor pumps to provide reliable performance at scale.

Materials compatibility is another critical factor. Elastomeric seals may be used for chemical resistance in support systems, while nonmetallic wear parts reduce the risk of galling. Engineers also specify corrosion-resistant alloys and low-temperature materials for drain valves and piping. In high-capacity fertilizer or co-firing plants, drain valves are typically located away from the pump to further limit exposure risks.

Ammonia’s Expansion

As ammonia use expands to 320 million tons annually by 2030, so too will the need for safe and efficient pumping solutions. Power producers see ammonia co-firing as a promising near-term option for reducing CO₂ emissions, with the potential to move toward full ammonia firing in the longer term. Fertilizer and manufacturing facilities will continue to rely on large-scale ammonia storage and transfer systems, making leakage control and reliability paramount.

By eliminating mechanical seals and the risks they bring, sealless pumps are poised to play a larger role in these operations. Brautigam emphasizes that selecting the right pump—whether magnetic drive or canned motor—depends on the specific application, but the advantages are clear: greater reliability, fewer maintenance needs, and most importantly, a safer working environment.