Up To Speed: Troubleshooting Made Simple – Don’t Forget The Curve

06/13/2018

Up To Speed Graphic Thin Version

Up To Speed is a concise, technical blog compiled by industry veteran Mark Reeder. It provides an interesting fact, answers a thought-provoking question, or offers a cliffhanger from an actual site visit by one of our world-class Field Service Engineers.

This Up To Speed  topic comes from a Field Service Engineer visit to a mine in Southern California to diagnose the cause of large motor failures over the past few months. After reviewing a teardown analysis of each motor failure and the gallons per minute (GPM) delivered, he suspected the problems were due to an upthrust condition. The pump/motor assembly was operating on the far-right side of the pump curve, indicating a tremendous amount of water flow, with a small amount of pressure.

To verify that an upthrust condition was, indeed, the cause of the motor failures, the Field Service Engineer began troubleshooting with the customer asking, “What is the pump’s curve?”

There was silence, followed by the answer of “We don’t have the pump curve.”

When troubleshooting, it’s impossible to know where you are on the pump curve without having a copy of it on hand. Without the proper data that it shows—where the pump should be running in terms of flow and pressure (100 gpm @ 100 feet)—the Field Service Engineer could not confirm his assumption behind the failures.

Simple Ways To Find Your Pump Curve
Franklin Electric pumps are designed to operate within 20 percent of the pump’s rated flow. The pump curve provides the optimum level of pressure and flow in which a pump should be operating. This is also known as the best efficiency range. Any time while troubleshooting a potential issue, it’s critical to know if you’re operating either too far left, or too far right on the pump curve.

Luckily there’s an easy solution for this.

  1. Find the model number of your pump. 
  2. Easily generate the pump curve via the Franklin Water site or FE Select.

To access via the Franklin Water site, within the Submersible Pumps category on the Products page:

  1. Select the submersible pump type (i.e. 4-inch, 6-inch, 8-inch, etc.).
  2. Select the Downloads box on the far right, immediately followed by the pump name catalogue series PDF file underneath. The pump curve (pictured below) is found within the product catalogue download. 

 Curve Graph 1The Franklin Water site can be used to access a copy of your pump curve.

To access via FE Select, find your pump’s curve by:

  1. Choosing Select from List of Products within the Pump Finder category.
  2. Select the Market from the top left drop down menu, followed by check marking the appropriate product line catalogue.
  3. Hit the yellow Next button.
  4. Choose the model of your pump and FE Select will display the pump’s curve.

Curve Graph 2The FE Select App can also be used to access a copy of your pump curve.

Back to the site visit.

The Field Service Engineer returned to the site and this time the pump curve data was on hand. The cause of failure was exactly what the engineer had suspected—an upthrust condition. The pressure was adjusted using a ball valve to correct the placement on the pump curve, allowing the pump to have a long service life.

Now, you’re up to speed.