|Filter Element Options for Traps
Many different types of
trapping media have been devised to help eliminate all those nasty things from getting
into your vacuum pump. The best method to determine the correct trapping media to employ
is to make a list of all the chemicals or items that you feel could potentially get sucked
into the vacuum pump. After you have your list together give us a call. There are so many
different types of things being done with vacuum pumps, it gets a little overwhelming to
try and have a fix for all of them. We do have some solutions and the ones following are a
good cross section and relatively inexpensive. We also have more sophisticated solutions
available that can get pretty expensive but can also get much more effective.
From all the pumps we see at our factory back for service
or repair there is no doubt that foreign contamination is one of the largest slayers of
all types and makes of vacuum pumps. We see pumps all rusted up and with oil that just
slumps out of the case it is so contaminated and oxidized. To the other argument we have
pumps that have been in service in excess of 40 years with out a hitch. A little planning,
protection and care goes along way with these machines.
Neut - Employs Potassium hydroxide
(this is a very basic chemical) in a filter element to neutralize acidic
vapor streams. There is a blue indicator included in the element to tell when the trap
becomes loaded. When an acid comes into contact with an alkaline or basic chemical that is
present in the trap, there is a reaction and water and salt creation are the byproducts.
By neutralizing the majority of the acid stream the pump is more protected.
Activated Carbon - Typically this filter is used to
trap organic solvents like aliphatic and aromatic solvents. The filter can be expected to
trap 20% by weight of solvents coming across from the system. As this type of filter
element loads with solvent, the user will see an increase in pump down time to reach the
vacuum pressure desired. Because the material is micro-crystalline graphite it is a good
selection for trapping oils and hydrocarbon based products. This type
of material can also be employed to trap mercury.
Activated Alumina -
Used for high molecular weight
hydrocarbon molecules and is also effective for acidic streams.
Copper Mesh - These are a filter for
particulates. They provide a large surface area for the trapping of some condensable
vapors but the main purpose of this filter is to keep large coarse particles out of the
pump. They also help in backstreaming oil but the molecular sieve
traps are more effective.
Cellulose Acetate -
A good filter which can double
as both a particulate and strong acid filter. It is constructed of virgin wool and cotton
fibers. These traps adsorb the material and hold it on their very large surface area. They
are a good choice for small particle trapping as they can reach retention sizes in the low
Mercury Traps - See Activated Carbon
Molecular Sieve - Uses 13x zeolites for
trapping. Usually employed to stop oil back streaming from vacuum pumps at low pressures.
Zeolites are chemical items that look like a sponge under the microscope. The pours in the
zeolite are what trap the molecules. These trapping elements are often used for limiting
an activity known as oil back streaming which occurs in oil sealed rotary vane pumps where
the oil in the pump is exposed to high vacuum pressures for extended periods of time. Some
traps (not VITs) can be heated to actually purge trapped molecules and as a means to
regenerate the zeolite material employed.
Pleated Type - Standard HyVac particulate
trap comes in 5 or 10 micron retention sizes our standard is 10 micron that
comes in the basic traps. We also have available 1 and 2 micron filters
for very fine dust.
Stainless Steel Mesh - Used same as copper mesh but
made from 304 stainless steel. It is the material of choice for particulate trapping in
systems which tend toward more acidic or basic vapor streams. Also
help in oil backstreaming but molecular sieve are more effective.