24
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July - August 2016
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www.machinerylubrication.com
CASE STUDY
The engine oil requirements for this
biogas engine are stringent and allow little
compromise. Oil changes for this machine
are driven by oil analysis. The staff 's accu-
mulated knowledge and experience with oil
analysis has helped keep this valuable asset
in peak operating condition. Factory repre-
sentatives have commended personnel
several times for keeping a tight rein on
engine maintenance.
One event occurred recently where the
base number for this engine's oil dropped
sharply into a caution range well before
customary oil life was reached. Additional
oil tests were conducted, and similar results
were obtained. When the engine manufac-
turer's representative was consulted, it was
suggested that the content of the biogas be
checked. An investigation revealed that the
biogas scrubbing elements were exhausted
and allowing excessive hydrogen sulfide to
pass. This caused the oil additive to deplete
and lower the base number. This was
another win for oil analysis. It also improved
the awareness of maintenance require-
ments for the scrubbing system.
As interest in lubrication grew, UOSA
began to experiment with kidney-loop
filtration systems where a cleanup filtering
might resolve a marginal lubricant condi-
tion. The first targets for this process were
the large gear drives on the circular clari-
fiers. Some of these drives have a capacity of
nearly 30 gallons of oil. Hauling a portable
filter set to the location made better sense.
Technicians connected the filter set and
monitored filter back pressure during the
filtering period. A follow-up oil analysis
sample was taken to confirm an acceptable
oil condition and check the process. The
overall savings in material and labor have
made this an attractive maintenance option.
An oil sight glass with dirty oil (left) and clean oil (right)
