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Eliminating the Use of Mercury
Manometers in the Dairy Industry
| Company |
Dairyland
Equipment Services Inc.,
Plainview, Minnesota, in conjunction with the Wabasha
County Solid Waste/Recycling Office |
| Results |
The Mercury
Manometer Replacement Project—a manometer changeout
program
for dairy farmers throughout the state—replaced
1,353 manometers with a non-mercury gauge and removed
1,134 pounds of potentially hazardous mercury from
dairy farms and the environment. |
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Process Background
Dairyland Equipment Services sells,
installs and services milking systems for dairy farmers within
a 60 mile radius of Plainview, Minnesota.
Milking systems have vacuum lines that remove
and transport milk from cows’ udders to a bulk tank.
As part of this system, vacuum gauges measure pressure in
the vacuum line. By monitoring the gauges, farmers can be
alerted to large pressure fluctuations in the vacuum line,
which can result in health problems for the cows or indicate
operational inefficiencies.
Mercury manometers are one type of vacuum
gauge used in milking systems. Each gauge has a U-shaped plastic
tube containing 0.781 pounds of mercury. The mercury in these
manometers can become contaminated with water, milk, dirt
and cleaning chemicals. Also, the plastic mercury-containing
tube can become discolored and cloudy. These problems make
the manometers difficult to read accurately. Once this occurs,
Dairyland must repair or replace the manometers and manage
the waste mercury.
After removing contaminated mercury manometers
from the farm, service technicians return to the shop and
drained the mercury into a sealed storage container. When
Dairyland accumulated up to 25 pounds of mercury, it contacted
its county solid waste officer for assistance transporting
the mercury to a recycling company.
Incentives for Change
Dairyland initially contacted the Wabasha County solid waste
officer in 1994 to find out how to dispose of 25 pounds of
mercury it had accumulated from servicing mercury manometers.
After learning about the need for proper
mercury management, Dairyland was concerned about the potential
for mercury spills when service technicians filled new manometers
with mercury, and about the collection, storage and disposal
of used mercury.
Because Dairyland was interested in reducing
future disposal costs and liability associated with mercury,
it began replacing contaminated mercury manometers with bourdon
(spring) gauges—a nonmercury-containing alternative.
Mercury
Mercury is a toxin that has been associated with nervous system
disorders. When mercury enters lakes and streams, it can build
up in the tissue of fish and result in high concentrations.
Minnesota issues advisories cautioning people to limit how
much fish they eat from waters in the state.
Intern Activities
Under the direction of Dairyland and Wabasha County, the MnTAP
intern evaluated the use of mercury manometers in Minnesota’s
dairy industry and researched alternative vacuum gauges. The
intern conducted a survey of 85 dairy equipment dealers to
1) determine which dealers offer mercury manometers,
and 2) estimate the amount of mercury present on dairy farms
and at equipment dealerships.
Volume of Mercury
Responses from the equipment dealers survey indicated that
nearly 20 percent of all Minnesota dairy farms—2,357
farms—had mercury manometers. These manometers contained
a total of about 1,825 pounds of mercury. An additional 205
pounds of mercury were in storage or in use at dairy equipment
dealerships. In 1994 alone, Dairyland accumulated 15 pounds
of waste mercury for recycling.
Alternative Gauges
Based on current dairy industry standards for vacuum gauges,
accuracy, durability and cost, the intern found that bourdon
liquid-filled gauges and digital gauges were acceptable alternatives
to mercury manometers.
Bourdon liquid-filled gauges. The intern
determined that the bourdon gauges need to be stainless steel
and filled with oil. Stainless steel will prevent corrosion
by contaminants, and oil dampens vibrations resulting in smaller
needle fluctuations and greater accuracy. The oil also lubricates
the moving mechanical parts, which reduces wear. Similar gauges
are currently used in the dairy industry and retail costs
are comparable to that of mercury manometers.
Digital gauges. Digital gauges give more
precise readings and have a higher degree of accuracy than
mercury or bourdon gauges. Unlike other gauges, digital gauges
require a power source. Because the gauges are in use at least
35 hours per week, the intern suggested that the gauges be
powered by the same source as the milking system so they can
be turned on and off with the system. A few digital gauges
were in the price range of mercury manometers.
Equipment manufacturers recommend that service
technicians use a bourdon gauge or digital gauge to test the
milking systems they are servicing. The gauges used in the
field should be calibrated with a mercury manometer kept at
the shop.
Conclusion
Dairyland plans to continue replacing contaminated mercury
manometers with nonmercury-containing gauges to help reduce
the amount of mercury on Minnesota farms.
With support form a Legislative Commission
on Minnesota Resources grant, the Minnesota Department of
Agriculture conducted the Mercury Manometer Replacement Project.
The manometer changeout program for dairy farmers throughout
the state replaced 1,353 manometers with a nonmercury gauge
and removed 1,134 pounds of mercury.
Management Options
The Minnesota Pollution Control Agency (MPCA) recommends the following management options when replacing mercury manometers.
- Take mercury and mercury manometers to a mercury recycling facility or arrange with a waste hauler to take them to a recycling facility. A sample list of mercury recycling facilities is included below. Contact recyclers directly for shipping information, prices and a list of haulers that serve their facilities.
- Check with dairy equipment dealers to see if they accept mercury or mercury manometers for recycling.
- Check with the county solid waste office to see if any other services are available in the area.
- If accessible management services are not available, store mercury and mercury manometers until services are established in the area.
Storage
Always store mercury and mercury manometers removed from service
in covered leak-proof containers, such as small plastic buckets
with sealable lids. Mark containers as appropriate: “Mercury
for Recycling” or “Mercury Manometers for Recycling.”
Shipping Invoice
When shipping mercury or mercury manometers to another location,
an invoice must accompany each shipment. That invoice must
include the date of shipment, the amount of mercury or number
of mercury manometers in the shipment, the location from where
the waste is being shipped, and the destination of the shipment.
Keep a copy of each invoice as a record of the shipment.
Mercury Recycling
Facilities
MnTAP maintains this list of mercury recycling facilities
solely as a service to Minnesota companies. This is not a
complete list of facilities and does not represent an endorsement
by MnTAP. MnTAP, by providing this list, does not represent
that the services do or do not ensure
compliance with environmental and safety laws in any specific
application.
DFG
Mercury Corp.
Evanstown, IL
847/869-7800
Mercury
Waste Solutions, Inc.
Roseville, MN
651/628-9370
887/636-6514
For More Information
MnTAP has a variety of technical assistance services available to help Minnesota businesses implement industry-tailored solutions that maximize resource efficiency, prevent pollution, increase energy efficiency, and reduce costs.Our information resources are available online. Or,
call MnTAP at 612.624.1300 or 800.247.0015 from greater Minnesota
for personal assistance.
This project was conducted in 1995 by
MnTAP intern Charlie Radman a Biosystems and Agricultural
Engineering student at the University of Minnesota.
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