Mercury Exposure Risks from Natural Gas Equipment

Photo by Danny Smith

Photo by Danny Smith

Elemental mercury once played a significant role in the measurement of natural gas flow from interstate pipelines to local gas distribution companies and from local distribution companies to large industrial and commercial customers where the gas flow was measured using mercury filled manometers. Natural gas manometers measure the pressure differential of natural gas in a pipeline. Mercury manometers have been used in the natural gas industry on individual wells, pipeline junctions, pipeline manifolds, compressor stations, and distribution points. These manometers contain between 3.2 and 54.5 kg of mercury. A common design for manometers is a U-shaped tube with one end opened to the atmosphere and the other connected to a process. Pressure differential is measured by comparing the liquid levels in each of the two vertical sections of the tube.

In many homes around the country built before 1968, elemental mercury-filled regulators were used to limit the natural gas pressure flowing to household appliances. These residential pressure regulators typically contain about 135 grams (2 teaspoons) of elemental mercury. Elevated mercury vapor levels and elevated mercury soil concentrations are often detected where these mercury-filled devices were once installed or are currently located. Where liquid mercury has been spilled, there is also the potential for the mercury to be unknowingly tracked throughout the home, as well as to other residences and vehicles.

Another potential source of mercury is residential thermostats. Some household thermostats contain mercury switches where mercury is contained in one or more glass bulbs inside the thermostat. There is a risk of a mercury spill if the item is broken.

Elemental mercury vapor is a colorless and odorless gas and harmful levels, from relatively small spills, can go undetected for long periods of time. The assessment and remediation of mercury spills from these devices can present complex challenges. Primarium, LLC can assist with mercury spill assessment and response strategies.

Some useful guidance on mercury spills in the natural gas industry follows below.

Danny Smith