Version with oil return valve (RA ... C,
0.5 mbar):
The oil return valve does not work properly or
is clogged (proper function is when blowing
into the valve it should close, when vacuum is
applied, the valve should open; CAUTION: do
not let your mouth get in direct contact with
the oil return valve, do not inhale through the
oil return valve!)
Clean or replace the oil return valve
The oil return line is clogged or broken
Clean a clogged oil return line
Replace a broken oil return line with an identi-
cally dimensioned line, top up oil (if necessary
by Busch service)
The oil is black
Oil change intervals are too long
The oil was overheated
Flush the vacuum pump
Replace the exhaust filter
Fill in new oil
(
Ú
page 9: Maintenance)
In case the oil life is too short: use oil with
better heat resistance (
Ú
page 18: Oil
) or ret-
rofit cooling
The oil is watery and coloured white
The vacuum pump aspirated water or signifi-
cant amounts of humidity
Version with gas ballast:
The filter of the gas ballast is clogged
Flush the vacuum pump
Replace the exhaust filter
Fill in new oil
(
Ú
page 9: Maintenance)
Modify the operational mode (
Ú
page 8: Op-
erating Notes
Ú
Conveying Condensable
Vapours)
Version with gas ballast with paper filter:
Replace the filter
The oil is resinous and/or sticky
Improper oil type, perhaps in confusion
Topping up of incompatible oil
Flush the vacuum pump
Replace the exhaust filter
Fill in new oil
(
Ú
page 9: Maintenance)
Make sure the proper oil is used for changing
and topping up
The oil foams
Mixing of incompatible oils
Flush the vacuum pump
Replace the exhaust filter
Fill in new oil
(
Ú
page 9: Maintenance)
Make sure the proper oil is used for topping
up
17
