Welch Vacuum 1376N Chemstar - Manual (Page 23)

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Part 1 Health & Safety
The pumping of corrosive gases not only can shorten the service life of a vacuum pump, but also if not operated properly,
it can be hazardous to you and personnel around you. Throughout this application booklet, special safety precautions
which must be observed during installation and operation of the CHEMSTAR vacuum pump.
Warnings: A warning signifi es that failure to observe the instructions provided can lead to injury or death to personnel.
Cautions: A caution signifi es that failure to observe the instruction can result in damage to equipment.
Welch provides these WARNING and CAUTION notes to make you cognizant of the consequences of failing to observe
the instructions provided. Failure to observe these instructions can impact your safety and that of others in the vicinity of
the pump. In addition, failure to observe these instructions can lead to signifi cantly shortened service live of the vacuum
pump.
You must be aware of and understand the proper procedures before working with the vacuum pump. A review of all your
operating procedures of your complete vacuum system, not only the vacuum pump, by safety offi cials at your facility prior
to start-up is strongly recommended by Welch.
Part 2 Building a Vacuum System to Handle Corrosive Gases
A. Selecting the Correct Vacuum Pump Oil
Oil has four important roles in your vacuum pump:
(1) The oil lubricates moving mechanical components such as the lip seal, and vanes.
(2) The oil provides the seal between rotor and stator.
(3) The oil facilitates the opening of the exhaust valves during fi nal compression
(4) The oil removes the heat generated during compression.
Now knowing the oil’s role in your vacuum pump, you can see why the oil chosen will have a dramatic impact on the
service life of your CHEMSTAR vacuum pump. For this reason, Welch recommends DIRECTORR® Gold Oil be used
with each CHEMSTAR pump when pumping corrosive gases.
DIRECTORR Gold is a totally new type of hydrocarbon oil which is a formulated oil rather than refi ned base stock oil. This
product was developed to replace costly perfl uoropolyether oils such as Fomblin® and Krytox® in non-oxygen enriched
systems.
Several reasons exist for why DIRECTORR Gold is a superior hydrocarbon oil for corrosive gas applications compared to
standard hydrocarbon oil. These reasons are:
1
Less reactive to chemical attack. DIRECTORR Gold is a highly saturated and hydrogenated oil
which creates a high purity product. By vacuum distilling off a narrow fraction of this oil, Welch has
produced an oil with more single bonds than other oils. Fewer double bonds make it a less reactive oil.
2 Exceptional resistance to water emulsifi cation. Since the oil is saturated it exhibits less water
emulsifi cation compared to standard distilled pump oils. Since water may be in your corrosive gas
stream, less water emulsifi cation facilitates passage of corrosive gases out of the pump rather than
residing in water logged oil.
3 Low phosphorus content. Phosphorus is one of the most reactive elements present in hydrocarbon oil.
DIRECTORR Gold has less than 1 ppm of phosphorus where as standard vacuum distilled oil typically has 3000 to 4000
ppm. Some corrosive gases will combine with phosphorous and under pump operation breakdown oils forming acidic
sludge.
CAUTION
Theuse of standard Hydrocarbon vacuum pump oil can cause premature failure
of CHEMSTAR pumps