About Oil Mist Detection
In this section we believe we can show
you how we have overcome the problems associated
with oil mist measurement.
Why use outdated oil mist detectors when
the disadvantages have been overcome as
follows:
- Very slow response time: so that seizures
or explosions have often taken place before
the equipment gives an alarm.
The reason this happens is
the instrument takes oil mist samples through
pipes which is a slow process and, at the
same time, causes the oil mist to condense.
Further time is lost as a good concentration
of oil mist is required for sampling. Samples
are then taken one by one to evaluate the
levels of oil mist after which a deviation
is required to operate the alarm. These
processes all add up and the sampling time
can take between 30 and 50 seconds whereas
our instrument will operate within half
a second when properly installed.
- False alarms: The main cause of false
alarms is the use of obscuration as a
measuring system. This is not a sensible
method of measurement as it is dependent
upon the amount of light that is available,
therefore, when the lenses become contaminated
a false alarm can occur.
These systems require clean
compressed air that is not always available.
Invariably the air is not clean which causes
the lenses to become contaminated very rapidly
resulting in false alarms.
- Blocked siphons that become flooded
with oil so that the instrument cannot
function correctly.
- Valves: that can stick.
- Spares: are often difficult to obtain
and, if available, they are normally very
expensive.
The list goes on, but the
main problems have been given above.
The main advantages of the QMI Multiplex™
Oil Mist Detecting System over others:
A 500-m/sec. response times
when the detectors are correctly mounted.
Will monitor up to 12 detection
points simultaneously.
The monitor is mounted in
the control room or on the bridge away from
any danger zone where injury can be caused
to engine room personnel
There is no pressure regulator
that can be tampered with which would increase
sample flow causing drop out or condensation
of oil mist.
No need for a heater to
deal with condensation problems
Oil mist is measured at
source and the response time will not be
delayed by oil mist having to travel along
pipes where it also condenses.
There are no moving parts.
The fan is not an integral part of the monitor.
No expensive clean compressed
air is needed which is not always available
in good supply, especially during engine
start up.
A monitor that needs no
setting up on a running engine as the detectors
are calibrated at the factory and have a
true zero reading.
There are two levels of
alarm i.e., an early warning and a main
alarm together with a shut/slowdown facility.
A self-diagnostic fault
finding system which indicates all the instrument
faults that could occur. All types of faults
are displayed on the monitor so that the
user is kept informed and need not fear
false alarms.
Monitor will work even when
one of the detectors has developed a problem
A monitoring system that
can oversee more than one engine; monitor
oil mist in the atmosphere around the plant,
at the same time enabling detection of hazards
before fires start.
An instrument that is able
to monitor the gearbox bearings together
with the pistons and external surrounding
for oil mist.
In other words, this all becomes
part of the overall health monitoring of
the engine and not just an alarm system.
It enables the user to keep a watch on the
condition of the engine so that preventative
action can be taken early enough, saving
time and money by avoiding serious breakdowns.
You can read more about oil
mist detection in these three papers which
we have here available in pdf format. Just
click on the title to download.
Oil Mist Detection In The Atmosphere Of The Machine
Rooms - New regulations for atmospheric oil mist detection (PDF format-476K) This paper was presented to the Marine Propulsion conference in Bilbao, January 2005.
Oil
Mist Detection as an Aid to Monitoring an
Engine's Condition (PDF format-518K)
by Brian
J. Smith AIMarEST, MIDGTE
Winner of the Akroyd Stuart Award 2001.
First printed in the The Power Engineer,
Journal of the Institution of Diesel and
Gas Turbine Engineers
You will need the Adobe Acrobat
Reader (free) in order to view pdf files.
Click here
for the Adobe site and step-by-step guide
to installation.
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