How Gas Pressure is Explained Through Water and Bubbles

Throughout the natural gas journey, one of the challenges is lowering gas pressure along the way in order to fit the appliance need for a consumer. The transition to usage means reducing as much as 1,200 pounds of pressure (PSI) all the way down to one-quarter PSI that gas appliances operate at. This is made possible through the help of the gas pipeline system, specifically gathering lines (715 PSI), transmission lines (200-1,200 PSI), and distribution lines (¼-60 PSI.) However, it isn’t the pipeline itself that lowers the gas pressure, especially when the resource reaches the distribution part of the process. This is where the regulator enters the story.

A regulator is part of the gas meter set and ensures that the proper amount of pressure gets from the meter to the home or building. At this point, gas cannot be measured in PSI units because the pressure required is too low. Low pressure in the natural gas industry is defined as any pressure below one pound per square inch (PSI). However, instead of saying ‘low pressure’, industry experts use the term ‘inches of water column’. This refers to the amount of pressure it takes to raise a column of water by one inch. One pound of pressure can be measured using 27.7” of water column while the average home only requires about 7” of water column.

In demonstrating how the transition from PSI to inches of water column works, all it takes is some water, pressure, and the presence of bubbles. For example, if you lowered a pipe into water with one pound of air pressure pushing downward, the air would allow bubbles to surface until you reach 27.7”, also know as one PSI. See this in action by viewing the video below, a demonstration performed by A.Y. McDonald Gas Product Manager, Nicole Neuhaus.

There’s a reason and an explanation for every transportation aspect of natural gas to the consumer. And it goes to show that with a little water, pressure, and bubbles, we can clear up any confusion you may have on where PSI and inches of water column measurements originated from. Learn more about the topic by taking the 'Natural Gas Pressure' AYU course.