Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors

Overcoming Challenging Suction Configurations through Pump Testing

Hydro
Hydro Overcoming Challenging Suction Configurations through Pump Testing (2)

Overcoming Challenging Suction Configurations through Pump Testing

A municipal water treatment plant recently had one of their service water pumps refurbished. The refurbished pump is a single-stage, bottom suction BB1 (between bearing) pump with a double suction impeller. In order to validate the performance of the pump, the plant requested testing services from the Hydro Performance Test Lab. The testing services included a Hydraulic Institute certified performance test, a Net Positive Suction Head (NPSH) test, and a bearing housing vibration test.

The bottom suction design of the pump provided some challenges in the design of the test layout and in conducting the NPSH test. The bottom suction design of the pump did not allow for the typical piping layout design. Instead, the mounting feet of the pump needed to be elevated and supported at least 5 feet from the floor to correctly connect to the suction manifold. Changing the pump mounting elevation meant that the motor also needed to be elevated and supported at the same height.

Hydro Overcoming Challenging Suction Configurations through Pump Testing (2)Conducting an NPSH test provided its own challenges. Because the velocity entering the impeller eye is reduced in a double suction design, the expected NPSHr is quite low. During an NPSH test, the NPSHr at a given flow point is determined by reducing the suction pressure with a vacuum pump or throttling the suction valve until a 3% drop in differential head is observed. Because of the low NPSHr in this pump, achieving the 3% drop in differential head required a decrease in suction pressure below atmospheric pressure.

Another challenge encountered during the NPSH test was that the setup of the test loop required an elbow connected to the suction flange of the pump . This elbow affects the pressure distribution in the suction piping and can affect the fluid upstream of the elbow where suction pressure is measured. Even with these difficulties, the test lab was able to achieve accurate results due to the testing experience of the team analyzing the data.

Hydro Overcoming Challenging Suction Configurations through Pump Testing (2)After the testing services, it was determined that the total differential head overperformed the Original Equipment Manufacturer (OEM) curve by 12%. In addition, the pump consumed approximately 13% more power than expected. This test provided the customer with accurate information on how their pump was operating and ultimately led them to consider trimming the impeller to better achieve the desired duty point.

Related Articles

Hydro Adopt a Higher Standard

Adopt a Higher Standard

Enhancing performance and extending product lifespan doesn't necessarily require major design or operational overhauls. Often, modest adjustments to the standards…

Related Whitepapers

Specification Tips to Maximize Heat Transfer: Plate and Frame Exchangers

Choosing the right plate and frame heat exchanger for your application Heat exchangers are widely used in various industries including chemical, oil & gas, power…

Selecting Pump Upgrades and Operating Modifications for Existing Chilled Water System

Problem Natraj Arjunan, engineer at L&T Technology Services in Chennai India, was tasked with reviewing and simulating an existing chilled water system to diagnose system…

All-New Hydraulic Design of an Electrical Automotive Coolant Pump

CFturbo presentation at ISimT-24 in Munich/Germany! The paper “All-new Pump Design of an Electric Automotive Coolant Pump” describes a joint development between TENGAM Engineering and…

How to Read a Pump Curve (and Why you Want to)

If you have ever worked with pumps before, be it in an installation, maintenance, or engineering capacity, chances are high you have seen a pump…

Comments

Leave a Reply

Your email address will not be published. Required fields are marked *