Title: MGP Glossary - NYS Dept. of Environmental Conservation
Headings: MGP Glossary
MGP Glossary
Content: Emulsion refers to a physical mixture of two liquids which will not fully dissolve in each other. Some emulsions (common examples include vinegar/oil salad dressing) will readily separate when they are allowed to stand undisturbed. Other emulsions (such as raw milk) may remain mixed for considerable lengths of time. Gas Holder (also known as a gasometer) is a large, expandable tank used to store gas at an MGP. The earliest gas holders were housed in circular brick buildings, built around a deep pit foundation which was kept full of water. A steel tank (open at the bottom) would rise and fall according to how much gas was being stored at the time. The water formed a seal at the bottom of the tank to keep the gas from escaping. Later, larger water-seal gas holders were built with an external steel frame to guide the tank as it rose and fell, but with no brick building surrounding the tank. Most MGPs contained at least one water seal holder, and many MGPs had several. As a group, these holders are referred to as pit holders or in-ground holders.