How To Convert Lbs/Mmscf To Ppm

Converting pounds per million standard cubic feet (lbs/MMSCF) to parts per mole (ppm) is an important mathematical calculation when determining the proper water content for a gas pipeline. If you have too much water in your pipeline, gas hydrates will start to develop, and these can turn into a clog and block the pipeline.

Step 1

Measure the water presence in your gas pipeline using a single-channel dew point hygrometer. Set the units desired to lbs/MMSCF.

Step 2

Multiply your lbs/MMSCF reading by 21 to get parts per million of water. This constant applies regardless of temperature.

Step 3

Compare your findings with the norms for the country or region through which your pipeline travels. In the United States, the accepted maximum water presence is 7 lbs/MMSCF, or 147 ppm. In Canada, though, it's 4 lbs/MMSCF, or 84 ppm.