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Plastic Mag-Drive Gear Pump Cast Iron Centrifugal Pump 316 SS Mag-Drive Regenerative Turbine Pump

DYNAFLOW
ENGINEERING, INC.

106 Egel Avenue
Middlesex, NJ 08846
Ph: 800-801-DYNA

                    (3962)
Fx: 732-356-9793


Dynaflow Regenerative Turbine Pumps
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Regenerative Turbine Pump vs Centrifugal Pump Top of Page
Similarities:

    Both regenerative turbine and centrifugal pumps are "velocity" type pumps. Each generates pressure and flow from the tangential and angular velocities imparted to the liquid by the speed and shape of the impeller. In both pumps, pressure and flow can be modulated by throttling a discharge valve.

Head capacity characteristics:

    The head-capacity curve displayed is indicative of a centrifugal pump (See Graph Below). Relatively large flows can be generated at low to moderate heads. At higher heads approaching "shut off" (no flow condition), the curve is nearly horizontal in direction. A slight change in head, as results from throttling a valve, can alter the flowrate substantially. A flow change of 5 GPM, as when moving from point A to point B on the curve (20 to 15 GPM), resulted by throttling a valve to increase the head by 3' or slightly more than 1 PSI of water pressure. Metering in this region of the pump curve is very imprecise.

Centrifugal Pump Curves


    Alternatively, the head capacity curve of a regenerative turbine pump has a different shape (See Graph Below). It is nearly linear and slopes downward. At low to moderate heads, the flow is typically much smaller than for a centrifugal pump. However, the slope never approaches a horizontal plane. Therefore, throttling a valve for a regenerative turbine will permit more precise changes in flow, without major overshooting or undershooting of the duty point. To throttle the flow of the regenerative pump from 20-15 GPM as shown on the curve, a head change of 34' or 14 PSI of water pressure is required.

Regenerative Turbine Pump Curve


Cavitation:

    In a centrifugal pump, liquid enters and exits the pump in one revolution of the impeller. During that short time frame the liquid velocity increases while the pressure initially decreases and then increases reaching a maximum at the cutwater (discharge point). If the liquid entering the pump is near its vapor pressure, it is likely that the initial drop in pressure will create vaporization of the liquid and cavitation in the pump, with possible damaging effects.

    In a regenerative turbine pump, liquid enters and exits the pump during several revolutions of the impeller. The velocity and pressure increases of the liquid are more gradual than for the centrifugal pump. A liquid entering the pump near its vapor pressure is less likely to experience the pressure drop that can cause cavitation due to the smaller pressure gradient of the regenerative turbine pump. Therefore, regenerative turbine pumps, typically, require lower net positive suction heads than centrifugal pumps.
Advantages of Regenerative Turbine Pumps Top of Page
Downward sloping, nearly linear head-capacity curve permits accurate throttling with a control valve; overshooting or undershooting of the duty point, which frequently occurs with centrifugal pumps, is minimized.

Modular balanced impeller elimintates axial thrust, removing a wear factor associated with centrifugal pumps

Handles 20% entrained gases; ideal for tank stripping where vortexing or cavitation can occur.

Upon tank evacuation, pump cavity remains filled with liquid, unlike centrifugal pumps; this resists dry run damage.

Capable of reversible impeller rotation, with an accompanying reveral of the suction and discharge porting.
Standard Materials of Construction (Alloy Pumps) Top of Page
The standard materials of construction of the MTA Series is 316 SS. Optional materials include Alloy 20, Incoloy 825, and Hastelloy C276.

Materials of construction for the standard pump are as follows:
Component Material
Housings 316 SS
Impeller 316 SS
Rear Casing 316 SS
Shaft 99.9% Silica Free Aluminum Oxide
Bearings Carbon Filled Teflon®
O-Rings Viton®
Composite Curve (Alloy Pumps) Top of Page
Regenerative Turbine Pump Curves
Standard Materials of Construction (Plastic Pumps) Top of Page
Materials of construction for the MT Series in polypropylene is as follows:
Component Material
Housings Polypropylene
Impeller PVDF
Rear Casing Polypropylene
Shaft 99.4% Aluminum Oxide
Bearings Carbon Filled Teflon®
O-Rings EPDM
Materials of construction for the MT Series in PVDF is as follows:
Component Material
Housings PVDF
Impeller PVDF
Rear Casing PVDF
Shaft 99.4% Aluminum Oxide
Bearings Carbon Filled Teflon®
O-Rings VITON®
Composite Curve (Plastic Pumps) Top of Page
Regenerative Turbine Pump Curves

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