Section 1. Health & Safety; Section 2. Building A Vacuum System To Handle Corrosive Gases; Selecting The Correct Vacuum Pump Oil - Welch CHEMSTAR 1374N Owner's Manual

Section 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 signifies that failure to observe the instructions provided can lead to injury or death to
personnel.
Cautions: A caution signifies 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 significantly 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 officials at your facility
prior to start-up is strongly recommended by Welch.

Section 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 final 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 refined base stock oil.
This product was developed to replace costly perfluoropolyether 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 oi 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 emulsification. Since the oil is saturated it exhibits less water emulsification compared
to standard distilled pump oils. Since water may be in your corrosive gas stream, less water emulsification 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.
Theuse of standard Hydrocarbon vacuum pump oil can cause
DIRECTORR Gold Oil is not inert and should not be used in environments
involving a high percentage of oxygen. The use of Directoor Gold Oil for
pumping a high percentage of oxygen can lead to a pump fire
CAUTION
premature failure of CHEMSTAR pumps
WARNING
and injury to personnel.