Chemglass AF-0349 Welch Vacuum Pump User Manual
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Oil Fill: Replace the oil drain plug, remove the plastic oil fill plug located on the top of the oil reservoir. Fill the
pump with vacuum oil until the level reaches the FULL mark of the label next to the oil sight glass. Do not overfill
the pump. The excess oil tends to splash out of the exhaust. Replace the oil fill plug. Check the oil level again
after the pump warms up to its normal operating temperature. Add or remove oil as needed. It is normal for the
oil level to change upon initial start up.
Frequency of Oil Changes
The oil change interval is completely dependent upon the running conditions of temperature, operating pressure, hours
of daily operation, and upon the materials pumped. Clean, dry air at pressures below 50 mtorr are the most forgiving
conditions. To determine your own oil change interval, visually monitor the pump oil conditions at regular intervals. If
you suspect harsh operating conditions, daily visual checks are recommended. When the oil becomes cloudy, dark or
includes particles of solids, it is time to change the oil. Oil may be visually checked through the oil level window.
However, a much better check is to use the drain to draw out 20-50 ml into a small glass beaker and view the oil with
a light behind it. Clean oil can be returned to the pump through the oil fill port.
Be sure to use only DIRECTORR® Premium or Gold Oil.
The ultimate pressure guarantee applies only if those oils are used.
6.03 Developing A Maintenance Schedule
After studying many examples of pump failure, Welch has found the most common reason is poor condition of the oil.
This is why a regular maintenance schedule for the oil is critical to obtain the longest service life out of your Vacuum
Pump. Welch recommends that you examine the condition of the oil on a daily basis in the early days of a new process
or experiment. Look for discoloration of the oil and whether the oil level is rising. The discoloration can indicate
deterioration of the oil, and a rising oil level can indicate condensation of vapors is occurring in the pump.
Once you have determined how long it takes for the oil to break down in your application, or become contaminated,
choose your oil change interval, so that the pump always operates with good quality, uncontaminated oil.