www.machinerylubrication.com
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March - April 2014
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There are several sample valve variations. Some are designed to
facilitate sampling from pressurized systems, while others require an
additional suction device to pull the sample from an unpressurized
system. One of the most common sample valves is called a minimess.
These types of valves are preferred because they allow sampling
without interfering with the machine's operation. They cause little
flow restriction with higher viscosity fluids and can be installed on
systems with pressures up to 6,000 psi. For
lower pressures (less than 750 psi), other valves
may be selected, such as the push or flush styles.
These can be installed on return lines, suction
lines, before off-line filters or similar locations.
If sampling within a sump cavity, a stainless
steel pilot tube of various lengths can be joined
with the valve to allow the sample's flow to be
originated from a representative location
within the sump, i.e., a "live-zone" location.
Possible sample locations for a splash/bath-lu-
bricated machine are shown above.
Sample Tube and Vacuum Devices
Along with the sample valve, a sample tube (or sample probe) will
be necessary to transfer fluid from the valve to the sample bottle. If
the fluid is pressurized, a probe-on sample bottle/tube configuration
can be used to extract fluid directly into the bottle through a lid with
two holes — one for the sample tube and one for air release.
If the fluid is not pressurized, a vacuum sampling device will be
Drop-tube
static sampling
Probe-on
static sampling
Probe-on drain-port
sampling with pilot tube
Off-line
sampling
Filter should be
put in bypass
prior to sampling
Risk of cross-
contamination
*Depends on ratio of residual oil volume
(in filter cart lines) to the total oil volume in
machine being sampled.
A new product recently introduced
by Luneta features a built-in sample port
(with a pilot tube) and offers quick access
to a variety of field lubricant tests. The
Condition Monitoring Pod (CMP) does
not simply act
like a level gauge
but also contains
a magnetic plug,
corrosion gauge
and other func-
tionalities all in
one. Visit w w w.
Luneta.com for
more information.
Condition Monitoring Pod
Sample locations for a splash/bath-lubricated machine