Tilak, that’s a great question. For some applications, yes. For others, no.
For example, if their system uses an old-school manometer for measuring evolved gases, operating at a reduced (or above atmospheric) pressure, or for use with a gas bulb to add specific amounts of gas to a system, it would be a tough sell for
some researchers. Moving to electronic gauges may not be practical in these cases given issues such as calibration for different gases, compatibility, pressure ranges etc. However, for *some* cases, yes, moving to an electronic gauge is indeed feasible and
should be encouraged.
Oil as a replacement in bubbler and manometers can work on a low vacuum or Schlenk system where your main interest is pressure relief - simply turning up the flow in the system can provide back flow protection equivalent to a traditional mercury
bubbler. But for high vacuum lines like these, there is usually a need for one traditional manometer which you need to pull full vacuum on. A mercury manometer only needs to be about a meter high because at full vacuum the height of the column is approximately
760 mm. Replace the mercury with oil and you’d need an oil manometer approximately 14 times as tall; simply not doable. Electronic gauges are the only practical alternative (although as I mentioned above, may not be feasible).
One area you’ll still find large amounts of mercury in these kinds of labs is diffusion pumps. While mercury diffusion pumps work fine, if money can be found to replace them with oil diffusion or turbo molecular pumps, then now is the time to
get those labs to change over. There’s no reason (other than lack of funds) to still use them.
One mercury-laden device you can’t replace is a Toepler pump, which uses a god-awful amount of mercury (a liter or so) to trap and measure evolved/consumed gases. They are very rare beasts these days and marvel of old-school technology. If you
come across one of these make sure that the PI has set up an appropriate secondary containment system for them! Video of one here: https://www.youtube.com/watch?v=MK3Pp8N4268
and a terrific
PowerPoint of how they work here: http://molan.wdfiles.com/local--files/toepler-pump/toepler.ppt
The power of these things for a certain set of narrow applications is incredible
- for example, let’s say you were studying the uptake or evolution of a mixture of H2 and CO. After making your measurement of the total amount of gas, you can cycle the system through a catalyst bed (“burn tube”) to convert the H2 to H2O, trap out the water,
and then directly determine the amount of CO (and therefore, H2) in that mixture. Very powerful. Of course, each of these measurements takes a couple hours because the cycle time of that pump is probably 30-60 seconds.
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Is it possible to replace the mercury with other safe alternatives, such as oil?
We have a building wide lab renovation project starting up that involves ventilation upgrades and installation of sprinkler systems. A number of these labs have glass vacuum line systems
that are 6-12ft long, some containing various mercury containing components. Due to the size and intricacy of the systems, there is a significant hazard involved with dismantling them and the labs would like to leave them in place and have them protected
in some fashion.
Does anyone have any recommendations to have them crated in place or whom would be the best type of company to reach out to? I wouldn’t trust a standard crating company with this project
and we are currently reaching out to the local scientific gas blower that made the systems for his suggestions.
Thoughts would be appreciated.
Brandon S. Chance, M.S., CCHO
Associate Director of Environmental Health and Safety
Office of Risk Management
Southern Methodist University
PO Box 750231 | Dallas, TX 75275-0231
T) 214.768.2430 | M) 469-978-8664
"… our job in safety is to make the task happen, SAFELY; not to interfere with the work…” Neal Langerman
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