Guest Column | September 23, 2021

Math Solutions Explained: Converting To Gallons Per Minute

Wastewater Dan Theobald

By Daniel Theobald, "Wastewater Dan"


The solution of the convert to gallons per minute (gpm) is to calculate a measure of how many gallons of water flow as an expression of gallons per minute. The flow rate can be converted and expressed for different times; however, this presentation will focus on converting and expressing flow rate gallons in minutes, converted from flow rate gallons in hours.

Before spotlighting details of the calculation, recognizing the impact of knowing and understanding the calculated conversion to gpm is described here.

To a wastewater operator, the conversion and expression of flow in gpm is useful in multiple applications, of which some are spelled out below.

  1. Convert the application of explicit chemical feed pump flow specifications as maximum pumping capacity in hours (gph) to expressing the upper limits of the pumping output in minutes (gpm).

The pump stipulations in hours are not adaptable to a timeframe compatible with the clear-cut wastewater treatment process operations in minutes modeled by operating step-by-step procedures.

Accordingly, changing the interpretation of pump flow rates from hours to minutes expresses the flow consistent with wastewater treatment operations.

  1. Convert manufacturing internal pump discharge flow rates in hours consistent with wastewater treatment flow operations in minutes.

Manufacturing requirements are unique to the process, such as describing pump flow rates in hours or the metric system (liter per minute [lpm] and cubic meter per second [cms]), which are different than representing wastewater treatment flow rates in the U.S. system (gpm).

It is advantageous to recognize when the flow rate labels are different from the requirements of characterizing flow rates in wastewater.

Thus, converting the flow rate is preconditioned by the wastewater treatment piecemeal operating procedures.

It is pretty meaningful to have working data compatible throughout all of the wastewater treatment documentation. The documents include (but are not limited to) source data, check sheets, and process-guided work procedures. If, for example, flow rates are incompatible throughout the system, converting flow rates are required. They are often changing the flow from hours to minutes as necessary.

It is favorable to understand essential wastewater mathematics solution components to become more proficient in calculating the conversion to gpm, such as:

  • Figuring out a word problem routine that makes several explicit features of word problems, including the numbers, the question, the equation, a model, and the answer;
  • Grasping that problem-solving requires identifying an appropriate formula or procedure and determining what information you will need (and what will not be necessary) to answer the question.

Familiarity with wastewater mathematics can be effective in furthering a wastewater operator's career.

Thus, I have created a Convert to gpm learning exercise.

I have also generated a series of wastewater math attainment activities that will continue to expand with more tasks.

This is the “Convert to gpm” presentation in my series of “Math Solutions Explained.” If you have specific wastewater math queries, please submit areas of interest or a question.