• Flexible Coupled

• Capacities to 150 GPM

• Heads to 1150 Feet

• Low NPSH Requirements on 250 • 260 • 270 Series

Water Passage Design

MTH has combined sixty years of water passage design with a multistage mechanical concept to achieve maximum capacity and pressure while minimizing horsepower requirements. By optimizing the number of pumping stages with each water passageway, MTH improves both efficiency and pressure in the 150 • 250 • 160 • 260 • 170 • 270 Series, exceeding the standards realized by previous techniques.

Impeller Profile

One of the most notable improvements in regenerative turbine pump technology incorporated in 150 • 250 • 160 • 260 • 170 • 270 Series pumps involves the ability to determine the optimum impeller width and blade length. These factors have a significant effect on the required horsepower versus pressure curve for regenerative turbine pumps. By optimizing these for each 150 • 250 • 160 • 260 • 170 • 270 Series pump, peak efficiency is improved and “off peak” horsepower requirements are reduced as well.

Impeller Blades

After the most favorable impeller profile has been determined for a particular water passageway cross-section, MTH calculates the number of blades needed to maximize the performance of that pump. Current blade design in 150 • 250 • 160 • 260 • 170 • 270 Series pumps increases both efficiency and design pressure without the manufacturing difficulties associated with producing contoured blade impellers.

State-of-the-art computer controlled machines simplify manufacturing of the various MTH impellers utilized in the 150 • 250 • 160 • 260 • 170 • 270 Series. The result is a high performance pump providing efficiency characteristics exceeding those of more expensive units.

NPSH Requirements

150 • 250 • 160 • 260 • 170 • 270 Series regenerative turbine pumps meet low net positive suction head (NPSH) requirements without efficiency loss. This is achieved by keeping the inlet fluid velocity low and then gently accelerating to passageway velocities.

Low NPSH Requirements

250 • 260 • 270 Series regenerative turbine pumps provide exceptionally low NPSH requirements to suit boiler feed water deaerator applications.

This reduced NPSH is obtained by using a first stage centrifugal Francis vane impeller with inlet flow paths shaped to maintain a constant fluid velocity. This reduces entry losses to the impeller as well as maintaining pump efficiency. A multi-vane diffuser is used in conjunction with the centrifugal impeller for balancing radial loads and extracting the maximum pressure from the flow produced by the first stage impeller. Pressure and flow produced by the low NPSH inducer assures that the succeeding stages are adequately fed.

200 Series Inducer for Low NPSH

The 200 Series inducer style pumps are ideally suited to applications where available NPSH at the pump inlet is limited, such as boiler feed water deaerator service. A centrifugal Francis vane impeller with low NPSH characteristics is utilized as the pump’s first stage impeller, accounting for the lower inlet head requirement. This first stage impeller is used in conjunction with a multi-vane diffuser to provide the NPSH required by the second stage regenerative turbine. Available NPSH as low as two feet can be effectively handled with 250 • 260 • 270 Series pumps, depending on the pump model and capacity.