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MERCURY-CONTAINING MANOMETER REPLACEMENT
Summary:
Mercury-containing manometers were used historically at the University of Michigan (U-M) Mechanical Engineering Department's Lay Automotive Laboratory, primarily to monitor the pressures of gases and vapors in engine test cells. The manometers were large, which made them cumbersome to use and transport from test cell to test cell.

As alternatives to mercury-containing manometers became more readily available and easier to use, the Lay Auto Laboratory and Department of Occupational Safety and Environmental Health (OSEH) collaborated to replace the mercury-containing manometers with mercury-free alternatives and recycle all of the elemental mercury from the old units. The replacement of mercury - containing manometers with electronic units eliminates the risk of breakage during operations and potential environmental issues pertaining to mercury spills.
Applicable Regulations
49 CFR 172.101 in the HM-215 Table.

40 CFR Parts 260-268.

State of Michigan Act 451 Part 111.

Overview of Procedure
Manometers are used to measure the pressure of gases and vapors. The Lay Automotive Laboratory primary use of manometers has been to monitor engine intake manifolds, engine exhaust pressures and other research apparatus where pressure monitoring is integral to research operations.

Waste Minimization Procedure
The mercury-containing manometers were removed from the Lay Automotive Laboratory by dismantling all devices and collecting the bulk of the elemental mercury in Department of Transportation approved mercury flasks. The remainder of these devices were treated as mercury contaminated materials and consolidated into 55-gallon steel drums. The contaminated devices were processed by retorting, which is a process in which the mercury is heated, vaporized, and distilled to be recaptured.

The project resulted in 63 mercury-containing manometers being replaced with electronic units, resulting in the recycling of 117 pounds of elemental mercury.

Known Limitations
There are still some instances where mercury-containing manometers are preferred, such as in determining barometric pressure, and in some pressure differential testing.

Safety & Health Precautions/Personal Protective Equipment
Follow all applicable safety and health protocols and regulations as established by your institution.

Benefits
The replacement of mercury-containing manometers with electronic instruments at the Lay Automotive Laboratory aids researchers in their work, as the replacements are typically hand held, easier to use, and provide more reliable data. In addition, the electronic units are safer and easier to move around from operation to operation than the bulky mercury-containing units.

The replacement of mercury-containing manometers has mitigated the potential for mercury to enter the environment from this equipment. Over a three-year time period there were several documented mercury spill cleanups in response to leaking manometers at the Lay Automotive Laboratory, several of which required more than one responder. The spills required a minimum of one hour of personnel time to clean the affected area of mercury contamination. The use of electronic units will eliminate the potential for mercury spills and the associated costs of spill clean up.

The time necessary to clean up a mercury spill varies according to how much mercury was spilled and the types of surfaces that must be cleaned; a laboratory benchtop, with a smooth surface, would take less time than a carpeted floor. However, the minimum cost to respond and clean up any type of mercury spill is approximately $150.

Disadvantages
None known.

Project Related Costs
Digital, hand held manometer
(Runs on a 9 volt battery) $645

Mercury-containing manometer

U-Tube manometer $171
Mercury 98
Total $269

 

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