|Before or After ? - Identifying and
dealing with a problem.
We are now making the
assumption there is contamination in the pump and that this is a very bad thing.
There are two basic methods of dealing with a contaminant.
Before it gets in the pump or after it gets in the pump and there are numerous solutions
First and foremost identify the contaminant. All
"things" in the universe have boiling points or sometimes technically referred
to as vaporization points. This is generically the temperature
at which the
"thing" turns into a gas. It can be below freezing or well above 1000 degrees
but all things have some specific temperature at which they boil and turn into a gas. If
you are working with a compound lets say an asphalt mix immersed in water there may be
numerous boiling points involved. The water being one, any solvent in the asphaltic mix, and
some tar like heavy oils. They all have different boiling points.
In using a vacuum, we can lower a "things" boiling
point. As an example water will boil at room temperature, 70 degrees F (Not 212 Degrees F)
under a full vacuum. This is basic physical chemistry and are scientific laws and can be
calculated should you so desire. The benefit to the user is reactions or extractions can
be done under varying temperatures and pressures and these reaction points manipulated
using vacuum pressure.
Another basic example is that under full vacuum levels of
various contamination can be manipulated or eliminated. "Water is in the process and
we want it out throw it in the vacuum oven and get it out." Cool no water......
hummmm..... Where did it go? In the pump.
Once you know what is in the pump then you can deal with it.
To stop a product from getting in the pump we use
what is called a "trap". These traps come in all shapes and sizes and we can
trap or stop lots of potentially bad actors before they get in and start attacking your
pump. Some basic examples:
Water - The main problem out there. There is only
one way to stop water effectively from getting into the
and that is to freeze it out of the air stream before the pump sees it. These traps are
generically called cold traps.
Solvents - Same as water but the traps can go to colder temperatures
depending on the
Particulates - Particulate traps of correct mesh size or micron size to stop the thing.
Mercury - Traps mercury
Acids - Neutralizing Traps convert acids to water and salt with a chemical reaction. Turn
a pretty blue color
Oil - Molecular sieve traps
Other traps and their information can
be reviewed on another page hot link from here for more information.
I added this because a lot of people have no clue as to the gas ballast valve present on
most of our pumps. We have a special page which you can hot link to but suffice to say
that for vacuum pressures in use; greater than 250 micron and problems with contaminants,
then running the pump with the gas ballast valve open or cracked may help significantly
the amount of contaminants that actually end up in the pump. Hot link here for more
After it's in the pump.
I want it out of the pump now!!!! Change the oil. Try running the pump for a couple
hours with the gas ballast valve open.
I want to deal with it regularly and efficiently.
You will need an external oil filtration system. These
systems can be hooked up to your pump to continually filter and remove unwanted
contaminants. They are a filter based system employing an external pump and can use
differing filters or even a series of filters depending on the problem to be solved.
You can also employ "water white" type vacuum pump
oils that start off with ultra low sulfur content in your pump. A little better on