How do you Convert ppm to pounds per gallon?

Answer 1

This question is poorly phrased. ppm or parts per million is a measure of the concentration of one element of a solution or gas. Pounds per volume is a measure of density and depends on the materials. The two measure different things and therefore there's no general conversion.

Many are the engineers that are trying to convert ppm in wastewater to actual pounds for reporting purposes. And pounds has more meaning to the average individual than ppm does. Generally speaking, one may take:

(ppm) x (flow of water (gal/"time")) x (conversion factor) = pounds per "time"

In this example, time = 1 month. Therefore, the ppm of a pollutant in water may be converted to pounds by following the following equation: (note: ppm = mg/l)

(mg/l)(gal/mo)(3.7854Lit/gal)(1Lb/453.59g)(1g/1000mg)=Lb/mo

The conversion factor = 8.3454E-06 or 0.0000083454

Above can be simplified as follows:

Monthly Gallons of Chemical x Density of Same Chemical in "Pounds/Gallon" x (# of Parts/1,000,000) (Unitless) = ...Pounds per month

If Unknown, Density = Specific Gravity x 8.345, i.e., Water Weight in Pounds per Gallon

Above both methods assume that PPMV value is in relation to the total volume of solvent or chemical used and not necessarily the total volume of inlet or outlet air of a process equipment. For PPMv of the outlet or inlet air, the calculations will be different as provided in EPA's AP-42 Conversion Table along with the use of air fuel ratio in case of combustion process.

Good luck!