MTH Pumps - X41 Series

MTH Pumps X41 Series Regenerative Turbine Pumps

Design Features

*Current X41 models are based on the T41 Series mechanically sealed pump hydraulics, while the future X51 models based on the T51 Series are available upon special request for higher capacities and pressures.

Design Features

The hermetically sealed pump/motor combination uses the process fluid itself for cooling, while a stainless steel barrier keeps the fluid isolated from the stator wire and rotor. A ceramic potting material is used to back up this .015 inch thick barrier to provide mechanical strength under high operating pressures. This special potting material is electrically insulating and also has the property of being highly heat conductive to help dissipate excess heat. Each and every pump is tested for barrier and containment integrity before shipment.

Optional inlet/outlet threading is available to match your system design needs. NPT threads are standard for North American usage for compatibility with low cost, commonly available pipe fittings. BSP is available for use with commonly available pipe fittings in England and associated countries, while ISO is used for applications where compatibility with international standards is important. SAE threads are also available for use where the most highly reliable leak-free connections are required.

The pump/motor units use three carbon bearings, with the motor rotor positioned between two thrust bearings, and the impeller supported on both sides to provide long running life. As with all plain bearing pumps, keeping pumping systems free of solids to prevent premature bearing failure is important. The X Series is, however, designed with easily replaceable bearings that can be changed out in a matter of minutes, providing a low cost means of maintaining "like new" performance over long periods. Specialized bearing materials are continuously being tested as new applications arise to allow further extension of useable life in harsh pumping applications. The rotor shaft bearings, as well as the turbine impeller, are easily replaced during scheduled maintenance events when used under severe operating conditions.

Like its T41 Series mechanically sealed counterpart, the X Series hydraulic passageways are designed to minimize thrust on the self-adjusting impeller to avoid upsetting its hydraulic balance, and to handle low NPSH conditions which can occur in some applications. New to the X Series is the location of the inlet and outlet on the centerline of the impeller to further eliminate the potential of axial imbalance that sometimes occurs during periods of marginal NPSH availability. With these design features, MTH has eliminated almost all of the bearing thrust loads in these units, and the motor thrust bearings exist only to provide axial rotor positioning.

Vent/drain taps are provided on both ends of the pump/motor unit to facilitate draining or air purging of the unit in either the horizontal or vertical position. Proper air purging at startup will help assure that the bearings are properly lubricated and minimize startup wear and priming problems. SAE fittings are used for both of these openings to assure a reliable leak-free fit, and to minimize the potential of galling that can be troublesome if over-tightening should occur.

All models feature top centerline suction and side discharge for best inlet conditions. The entire unit can be rotated every 90° to allow different inlet/outlet positions while maintaining best fluid entry, particularly when suction pressures are approaching the vapor pressure of the pumped fluid. There are no orientation restrictions when installing these pumps. Vertical mounting (pump up or down) has no effect on the unit's operation. This ability to mount the pump in any position gives the customer added flexibility in the design of their system.

Compactness also favors these canned motor pumps over magnetic drive pumps. In fact, most models are no larger than their equivalent close-coupled mechanically sealed pump/ODP motor cousins.


The X Series should be considered for applications where leakage cannot be tolerated. The sealless design ends down time and maintenance problems associated with mechanical seal pumps.

The compact size fits most OEM situations where close-coupled ODP motor/pumps will fit. These pumps can be easily mounted vertically, with the pump end up using the motor end cap as the base, or horizontally, using a standard or special mounting bracket, as necessary, to fit each application.

The X Series has fewer parts than most pump/motor combinations, which translates into easy assembly/disassembly for maintenance, and for lower manufacturing costs which ultimately means a lower price to the customer.

All rotating parts are enclosed, reducing ambient noise. No fans or ball bearings, which are typically sources of noise, are used. These pumps are exceptionally quiet due not only to their "plain bearing" design, but also because of refinements in the water passage hydraulics. This essentially eliminates the "high pitched whine" that has previously been associated with regenerative turbine pumps.

The sealless canned motor design offers significant advantages over magnetic drive solutions. The X Series pumps are actually integrated into the motor housing to provide a very compact package that eliminates the excess space requirement for a coupling, which is often critical in tight OEM enclosures. This design is also more reliable in that it has fewer parts and does not suffer from the magnetic de-coupling problems or degradation that often occur without warning in mag-drive units.


All standard X Series pump models have a 316 stainless steel housing and a non-galling Waukesha 88 impeller. The Waukesha 88 alloy contains 70% nickel which is typically more corrosion resistant than 316 stainless steel in most chemical applications.

A wide variety of "O" ring materials are available so the pump can be compatible with almost any fluid. Viton, EPR, Buna, Teflon, Kalrez, and other specialized materials can be made available to suit the application.

Bearings made of various carbon combinations are compatible with most fluids, while other bearing materials are available for testing in special applications upon request. The three bearings provide a large area for ample support of loads and long bearing life.

The selected motor insulation allows operation in high temperature applications. Windings are suitable for operation at temperatures of 200°C (392°F) and utilize NEMA Class N inverter grade insulation for use with variable frequency drives and to provide the longest life under all operating conditions.


Like other MTH products, 100% of X Series pumps are tested for proper operating characteristics before shipment. For specially requested longer term testing, a facility is available to simulate actual customer applications. MTH can operate a pump under the customer specified conditions for periods of time necessary to extrapolate minimum service life, recommended service intervals, MTBF, or other information. Testing quotations and proposals are based on the complexity of the required test, and with any special fluids being supplied by the customer.



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