Positive Flow Control with
Roth Regenerative Turbine Pumps


Control and use of Roth Pumps as represented on effective performance curve with flow schematic. (Drawing A-5304).


The “key” to the entire system.

Combining a “bypass valve” with a regenerative turbine pump provides user with a system which delivers both the:

Bypass valve settings are generally field adjustable. Valve is actuated by an increase in differential pressure (not total pressure). Valve cracking pressure is normally set 10% above the assumed design point. Valves are available in all common metals (316SS, steel, bronze, iron). Recommended supplier due to reliability, simplicity, and reasonable cost:

            Fulflo Specialties Company
            Blanchester, OH 45107
            Phone: (937) 783-2411

Pump horsepower is shown on the performance curve. Typical regenerative turbine pump BHP curve increases as flow decreases. Use of a bypass valve limits the BHP by limiting pump discharge pressure.


Effective pump performance curve should be compared to uncontrolled curve.

Uncontrolled curve is shown by blue line with X marks above bypass valve setting. Pump performance will follow blue line as pressure increases from zero to assumed design point; then it will follow the dotted line to a “zero effective flow” (flow to process).

The effective pump curve is one which shows:

High head, low flow and a wide operating range. (This range is desirable on many applications where the head may vary greatly or is hard to find.)

Slope of rising head/capacity curve that is gentle, modest, and continuously rising. (Exact amount of pressure rise is available from valve supplier.)

Pressure and BHP increase continuously to shut off.

Motor BHP limited to that corresponding to shut-off differential pressure.

Suggested Flow Control Schematic
For Roth Regenerative Turbine Pump

Pump Flow Control Schematic

Typical Regenerative Turbine Pump Curve
With Fulflo Pressure Limit / Bypass Valve

Regenerative Turbine Pump Curve w/ Bypass

Drawing No. A-5304

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Roth Pump offers a variety of of both chemical & industrial pumps for improving the operation and efficiency of commercial systems