Too Much Information? Not When Selecting Pumps –
A Discussion with Jim McCormick
(Application and Technical Engineer at SANI-PUMP, Inc., Sanitary Process Pumps and Equipment)
Too much information, or TMI as it's called in social circles, is a slang term meaning "I really didn't need to know that". It's used every day in legal speak, on Twitter and at the water cooler in your office, but it's rarely used by the people who size your pumps. We utilize several tools which assist us in selecting and sizing the correct pump for a specific need, including pump sizing programs, calculations and conversion software and well over fifty years of experience and knowledge in our sales and technical engineering departments.
The first task in sizing the proper pump is to obtain as much information about the client's application as possible. Let's review some of the data we request and why it's important.
Fluid Information will assist us in selecting which pump is best suited, Centrifugal, Rotary Lobe or Circumferential Piston Pump.
Temperature is critical to selecting the right seals and elastomers. In the case of Positive Displacement Pumps, it could also determine whether or not thermal expansion will occur, in which case, undersized rotors would come into play.
Viscosity is important information to the determination of what type of pump to use. Higher viscosity liquids won't move with a centrifugal pump and extremely high fluids may even cause suction problems which need to be considered.
Specific Gravity is necessary in determining pump model selection as well as power required to run it.
Flow Rate is crucial because in certain environments like breweries, for example, there may be a need to run the pump at a lower speed to prevent damage to the product, but require a high speed for CIP (clean in place). This is accomplished with the use of an AC inverter, also known as a VFD (Variable Frequency Drive).
Discharge and Suction Pressures must be calculated to get proper performance. This is why we ask questions like line size, total feet, both vertical and horizontal, number of elbows, presence of spray balls, filters, heat exchangers, etc. All of these factors combined tell us the friction loss in the application and is considered and converted into TDH, or total head-in-feet. The source of the liquid entering the pump inlet, like from an open tank, is important to determine if it will be adequately fed to the pump.
Seal Type is an important decision for the long term performance and reliability of the pump based on your application. Is the fluid tacky and/or abrasive? Does it crystalize when cooled? Single mechanical or double mechanical, carbon or silicon carbide material. Buna, EPDM or FKM? We will help you make the right choice. The primary reason seals fail is improper seal selection. Selecting a seal of improper geometry can result in unacceptably high friction and wear. Improper material selection can result in material failure or rapid or accelerated wear, causing costly down time and parts purchases.
Power Requirement accuracy is essential and we will determine the horsepower and speed requirements for you. What is often left unknown or unspecified is what type of motor enclosure is required. We offer Premium Efficient TEFC, wash down, stainless steel wash down, or explosion proof enclosures as well as special service motors like 575volt and 50Hz power.
To help you select a pump now, we created a "Pump Application Data Worksheet'' which addresses all the elements listed above. Once completed, we will have the information needed to prepare your pump, specific to your needs.