Be a Better Pump Buyer: 5 Things You Should Know for Pump Purchases

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Working with our PUMP-FLO program I get the opportunity to talk to many people involved in the pump selection process. These discussions occur with pump buyers, pump manufacturers, and pump sellers.
When I get into discussions about finding the right pump, I notice that these discussions tend to start sounding like Goldilocks and the Three Bears. You know the story, the Papa Bear’s porridge was too hot, Momma Bear’s porridge was too cold, but Baby Bear’s porridge is just right.
When I ask pump sellers about the amount of design details their customers give them for pump selection most of them say too little, some of them say too much, but very few say just right. It appears the answer is based on the market the pump supplier serves.

Meager Momma Bear
One common example is the pump buyer at a general industrial plant who may be purchasing a pump for a service system. This type of buyer most likely doesn’t provide sufficient information. For example a typical buyer might supply information like this:

• The buyer may say, “I need a 50 HP pump.” This doesn’t provide any help for the seller, but the buyer figures is as good a number as any to supply.
• A buyer may specify a pump size, say a 3x4-6. What they are telling the seller is: “I have a pump from another manufacturer that I’m having problems with and I would like to try one of yours.” More than likely, the pump is replacing an existing pump that failed because it was not originally sized properly for the application.
• Some buyers in this group may even provide a pump design point of head and flow value. This is a start but without specifying more information about the system, the pump sales person cannot get them the pump that is just right for their pumping application.

Papa Bear Information Overload
Buyers that specify too much information are typically working on application where they are specifying pumps for mission critical applications (power plants, refineries, chemical plants). It seems that some of these buyers provide the same level of details for all the pumps in a project, even the service water pumps, which are not nearly as critical an application.
In regards to specific pump details, the buyer should allow the pump seller to offer their recommendations for the best pump to meet their specified service conditions. By providing an excessive amount of pump details, the buyer may be excluding some of the sellers pump products that may be the best ones for their application.
There are circumstances where the buyer may want to use a specific pump standard such as API, ANSI, or FDA sanitary pumps. These standards are developed by a committee of pump suppliers and industrial pump users. The pump manufacturers that produce pumps adhering to specific standards all meet the requirement outlined in that standard.

So how much is Just Right? What does Baby Bear say?
How much information should you provide a pump sales rep when specifying a centrifugal pump? I asked some of my friends in the pump business to help me out on this one and here is what they said.

1. The first item in everyone’s list is to provide the standard pump design point items of pump head, flow rate, Net Positive Suction Head available (NPSHa), suction pressure, and discharge pressure.
2. Next are the properties of the liquid being pumped. This includes the liquid name, the fluid temperature, density or specific gravity, pH, viscosity, vapor pressure. If there is a wide range of operating temperatures involved, you should provide the above fluid properties for that range of temperatures. If there are any suspended or dissolved solids, you state that along with the amount and type of abrasives or other solids in the fluid stream.
3. If the pump is going to be called upon to operate under varying conditions you should specify the range of flow rates, and for each flow rate enter the head, NPSHa, and hours of operation at each condition. Often a design point given in step 1 is given for future requirements rather than the way the pump is expected to actually run. If that is the case, it is best to state that in the pump specification and then provide the expected conditions. This allows the pump supplier to choose a pump that can meet your future needs while operating efficiently at the current conditions. This information can be calculated using most manufacturers centrifugal pump selection software found on their Website, or at PUMP-FLO.com.
4. Installation details that should be supplied include the location of the installation, elevation above sea level, unusual ambient conditions, type of suction vessel or sump, along with any space or weight limitations. You can never supply too much detail on the installation.
5. Sharing Experiences. If you happen to lack experience with pumps in similar services, you can “go to school” on the pump manufacturer. Use their experience in these applications and ask sufficient questions about their products so you have an understanding of why they are making their recommendations. By asking multiple manufacturers the same questions, you will become an educated customer. Sharing experience is a two way street, for example if you have experience in a particular pumping application, say, material compatibility for a fluid being pumped, share it with the pump seller. That way they can “go to school” on your experiences. Remember life is too short for you to make all the mistakes, learn from others’ mistakes and save time.

One thing that I always consider great advice is that if the buyer has any questions as to their pumping applications or the recommended pump, pick up the phone and call the pump suppliers. They are very eager to answer your pump application questions. This gives the pump seller the opportunity to find out more about your application, and you can find out more about their products and how to properly apply their pumps. Remember by working together and getting the smartest people involved there is no limit as to what we can accomplish.
This article is a testament to this fact. I have been around centrifugal pumps all my working life, but I would not consider myself an expert. Much of this information came from pump people much smarter than me. I would especially like to thank Mike Volk, P.E. at Volk and Associates in Oakland CA, and Tom Angle of Weir Specialty Pump in Salt Lake City, UT for their detailed contributions to this article.
Now it’s time to hear from you. Do you have any tips or stories from past pump purchases? Share them! Please feel free to share your experiences, or opinions on this blog entry or any other subject that is of interest. I can be reached at blogger@eng-software.com.