Paper machine application – Vaisala MMT310 User Manual
Page 80
User's Guide _______________________________________________________________________
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Paper Machine Application
Typically, a paper machine contains two or three separate lubrication
systems. Usually, one is located at the wet end and the other at the dry
end. There is a certain amount of free moisture constantly present which
means that there is a risk of this moisture coming into contact with the
machine bearings. The most common reasons for the entrance of water
are an inadequate sealing of the housing and cleaning with high pressure.
However, accidental leakages from oil coolers and other equipment may
also cause damage.
In paper machines, the oil should absorb water while lubricating the
bearings and then release this water when collected into the reservoir. It
is to be noted that bearings should never be exposed to oils that have a
high water content; this is especially important during standstill because
the risk for corrosion process increases as the oil temperature decreases.
It is essential to monitor the water content and keep it on a suitable level.
When measuring the water content of oil in paper machines, it would be
useful to measure the water activity before an oil reservoir and from a
pressure line flow. This way, the performance of dehumidifiers can be
kept under control to ensure that no free water reaches the bearings.