Hydraulic Institute Pump FAQs October 2009
Q. What is the definition of specific speed, to what does it pertain and how is it used?A. Specific speed is an index of pump performance (developed total head) at the pump's best efficiency point...
HI Pump FAQs February 2012
Q. We plan to purchase several slurry pumps and understand that this service is considered severe duty. What guidelines should be followed regarding pump selection based on good wear resistance?A....
Pumps & Systems, March 2007Q.What are the key requirements for good suction piping design for rotodynamic pumps?A.  Good suction piping design must eliminate air entrainment in the liquid,...
Q. Is it true that centrifugal pumps should be built with ball bearings that have greater than normal internal clearance? A. It depends on the pump type and the conditions of service for the pump. ...
Hydraulic Institute Pump FAQs 2008
Q. I have heard that the rate of flow through centrifugal pumps can be regulated by submergence control instead of by throttling the pump discharge. How does this work, and does it damage the pump?A....
Q. We are operating a centrifugal pump, and a recent change in the system has resulted in a deficiency of about 5 to 10 percent in the rate of flow. Can anything be done to the pump to increase the...
Q.We have recently installed several double suction between bearing pumps and would like to verify that their vibration levels are within acceptable limits. How should this be done, and what is an...
Q. What does the expression discharge recirculation signify in rotodynamic (centrifugal) pumps? When does it occur, and is it harmful to the pump?   A. Discharge recirculation is circulatory...
Q. What is the maximum pumped liquid temperature that an end suction centrifugal pump can handle, and what must be done to a pump for it to operate successfully at that temperature?A. Limits are...
Hydraulic Institute Pump FAQs February 2007
Pumps and Systems, February 2007Q. We are operating a large axial split case pump which occasionally operates at about ten percent of its best efficiency rate of flow. At that rate of flow, the pump...
Q. We are expanding some of our buildings and need to replace the existing fire pumps. What are the technical requirements for such pumps?A. Pumps currently used for fire protection in buildings are...
Hydraulic Institute Pump FAQs January 2007
Q. I have been told that centrifugal pump impellers may still cavitate when operating with NPSH Available greater than NPSH Required. Is this true? If so, why do pump suppliers show NPSHR values when...
Q.  Most centrifugal pumps have a horsepower characteristic curve which rises as rate of flow increases to some level and then levels off or turns downward. However, other pumps have more level...
Hydraulic Institute Pump FAQs January 2010
Q. I understand the significance for properly configured suction piping, but what are the piping requirements on the discharge side of a rotodynamic (centrifugal) pump?A. The maximum velocity at any...
Hydraulic Institute Pump FAQs January 2011
Q. For centrifugal pump impellers, what is momentum change, and what is its significance?A. In single suction impellers the axial force related to the momentum of the incoming fluid should be...
Pumps & Systems, July 2008Q.Every pump manual clearly requires that a pump shaft must be carefully aligned with its driver shaft before operating the equipment. However, the precision of the...
Q. When installing a horizontal pump, is it better to grout the pump baseplate or let it float free?   Different sources provide opposing views on this subject.A. Whether to grout...
Hydraulic Institute Pump FAQs March 2009
Q. How can we tell if a pumping system is designed and operated properly? Some problems such as leaking seals are obvious, but should we watch for any other symptoms?A. A few symptoms in pumping...
Hydraulic Institute Pump FAQs March 2010
Q. Our pumps take their suction from an open tank. When the liquid level drops, surface vortices are formed that allow air to be drawn into the pumps. What changes can be made to the tank to correct...
Q. What is a steam pump? How does it work and where is it used?A. Properly called a "Direct Acting Steam Pump," it is a reciprocating (steam) engine and a pump liquid end built together as a unit....
Q. We need to increase flow through our system and plan on adding a second pump in parallel to the existing pump. Are there any pitfalls in doing this and how can they be avoided?A. Operating...
Q. Is it true that centrifugal pumps should be built with ball bearings that have greater than normal internal clearance?A. It depends on the pump type and the conditions of service for the...
Q. What symptoms are typical indicators of an inefficient pumping system?A. Many pumping system components are not dynamic. That is, these components allow fluid or heat transfer but, aside from...
Hydraulic Institute Pump FAQs September 2007
Q. What are the most probable causes of insufficient discharge flow or pressure in centrifugal pumps?A. Before looking at the pump, check the measurement of total head and rate of flow. The proper...
Hydraulic Institute Pump FAQs September 2008
Q. When operating centrifugal pumps on corrosive or erosive applications, how can the user determine when the casing wall is worn too thin for safe operation? What is the minimum safe operating wall...
Hydraulic Institute Pump FAQs September 2010
Centrifugal pumps: do they handle slurries, and what is their maximum allowable working pressure?Q. How do rotodynamic (centrifugal) pumps perform when handling slurries?A. The performance of a...
Q. What causes radial thrust on volute pump impellers? Should the pressure in the volute be uniform with proper design?A. Single and dual volute pumps are typically designed for uniform mean velocity...
Hydraulic Institute Pump FAQs August 2010
Q. What is the preferred method for starting reciprocating power pumps?A. Starting a reciprocating pump with a closed discharge valve is naturally difficult due to the high torque required to overcome...
Q. If industry guidelines for intake design are followed, when is it advisable to conduct physical model tests of intake structures?A. Industry guidelines cannot always be followed. A properly...
Hydraulic Institute Pump FAQs February 2010
Q. We have an application for pumps handling hot oil at 700 deg F. What special care should we take in selecting and installing such pumps? A. Pumps for handling oils within the range of 150 deg...