Atmospheric Oil Mist Detection System
TM4 / AUGUST 2018
EMAIL [email protected] WEBSITE www.oilmist.com 4 East Barnet Road, London, England, EN4 8RW TEL +44 (0)20 7328 3121
Sheet-12
POSITIONING OF Q10 ATMOSPHERIC SENSOR
We discuss below how the movement of oil mist in the atmosphere responds in working
environments and suggest how the placement of Sensors in an optimum position is
determined by flow of air. The Sensors may have to be adjusted when setting up the system
or even later when any structural alterations, machinery changes or more powerful fans are
introduced within the area.
There are so many variables in the detection of oil mist in the atmosphere that it is by no
means an exact science. Common sense has a part to play when positioning Sensors.
HOW MUCH AIR DOES THE SENSOR DRAW?
It pulls through 23 cubic feet/min or 0.65 m
3
/min
WHAT IS THE DETECTING RANGE?
There is no detecting range for the Sensor. The Sensor uses its internal fan to draw
in air, which is measured for oil mist. Three sensors inside the atmospheric Sensor
measure backscatter of light in the air drawn into the Sensor, and dirt on the lenses.
WHAT ARE THE FACTORS THAT DETERMINE THE POSITIONING AND NUMBER OF
SENSORS NEEDED?
Four factors determine good positioning and number of Sensors. These factors
should be considered together and a smoke generator is a good way to observe air
movement and test positioning of the Sensors.
a. Size of room or chamber (e.g. hydraulic pack area or engine room)
The fan in the Sensor has a through-put of 0.65m
3
per minute. In a large room, more
Sensors will allow a faster response. Also, dispersal of oil mist will be greater in a
larger space and will require more careful positioning on the Sensors in the path of
airflow.
b. Air circulation
In addition, the movement of air affects how many Sensors should be installed. If a
room has only one vent then the Sensor placed near this vent will be able to sample
the air extracted from the room. However, if there is more than one vent or point
of extraction a Sensor is best placed in each path of air being drawn from towards
each of these vents. This is why a smoke generator or a smoke test aerosol is used
to ensure that the Sensor points towards the potential source of oil mist. The Sensor
should be installed with the intake louvers facing the path of the smoke as shown
by the smoke generator. The smoke generator will also show any eddies or paths
that the air may follow in the chamber which is important to ensure that Sensors are
correctly positioned.
In hydraulic pack areas there should be a Sensor between each extractor and the
packs which normally means 2 to 3 Sensors especially if the pack is in the engine
room. This should be bourne in mind with any areas are being monitored.
