Specific Speed for Double Suction Pump and its Evaluation

Double suction pumps are types of centrifugal pumps that are designed to handle large volumes of fluid flow. The specific speed for double suction pumps is an important parameter that is used to evaluate and select the appropriate pump for a particular application.

Definition of Specific Speed

Specific speed is defined as the speed at which a geometrically similar impeller would operate if it were of unit size, delivering a unit volume flow rate against a unit head. It is a dimensionless parameter that is used to compare the performance of different pumps.

Evaluation of Specific Speed

To evaluate the specific speed of a double suction pump, the following steps are taken:

1. Determine the flow rate: The flow rate of the pump is determined by the application requirements.

2. Calculate the head: The head is the measure of the pressure that the pump can generate. It is calculated based on the discharge pressure required by the application.

3. Determine the impeller diameter: The impeller diameter is determined based on the flow rate and head.

4. Calculate the specific speed: The specific speed of the double suction pump is calculated using the following formula:

Ns = (N * Q^0.5) / H^0.75

Where:

Ns = Specific speed
N = Pump speed (RPM)
Q = Flow rate (m^3/s)
H = Head (m)

5. Compare the specific speed: The specific speed of the double suction pump is compared to the specific speed of other pumps to select the appropriate pump for the application.

Conclusion

The specific speed of a double suction pump is an important parameter that is used to evaluate and select the appropriate pump for a particular application. It is calculated based on the flow rate, head, and impeller diameter. By comparing the specific speed of different pumps, the most suitable pump for the application can be selected.

Half the actual discharge