Q&A with Ebara Elliott Energy: Best Pumps for Ammonia Applications

August Brautigam of Ebara Elliott Energy, at the 2025 Turbomachinery & Pump Symposia, addressed the optimal pump designs to handle ammonia’s inherently harsh characteristics. He identified two models—magnetically coupled and canned motor pumps—which offer minimal leakage and high-pressure containerization via differing technologies. Despite being suitable for ammonia integration, these pumps do exhibit a degree of operational difficulty.

Brautigam also offers some helpful insights for process engineers and operators: A higher flow application is suitable for magnetically coupled pumps, whereas a higher head application may lean toward canned motor pumps. Although each pump leans toward specific services, some magnetically coupled designs can manage high-head operations.

TURBO: Can you explain the main differences between canned motor pumps and magnetically coupled pumps for ammonia services?

Brautigam: Canned motor pumps have a canned motor stator and they’re similar to submerged motor pumps, which have been used in LNG for a long time. The canned motor stator is wrapped in a thin layer of stainless steel, similar to tinfoil, to keep out the ingress of ammonia. This technology is very suitable for high-pressure applications.

The magnetically coupled pumps are a relatively straightforward design. The pump and motor are on separate shafts connected by a magnetic coupling, and, in this design, a pressure barrier separates the outer rotating magnets from the inner rotating magnets to create a contactless, sealless pump. These are typically used for higher flow and lower pressure applications.

TURBO: What operational challenges are most common when using sealless pumps in ammonia systems?

Brautigam: The operational challenges associated with the retractable, magnetically coupled design include monitoring the nitrogen purge and installation is more challenging as purged flexible conduits must be installed. The flexible conduits are actually very stiff to work with, difficult to ship, and so on.

TURBO: How do you recommend process engineers and operators evaluate which type of sealless pump is best for their specific application?

Brautigam: It goes back to the process requirements, mostly flow and head. A higher flow application will likely be suitable for a magnetically coupled pump, whereas a higher head application may be driven toward a canned motor pump. However, we’ve produced a number of high head magnetically coupled pumps. High head and high flow cannot together be accommodated by a magnetically coupled pump due to limitations in the pressure barrier thickness.

Check out more from the 2025 Turbomachinery & Pump Symposia.