Typical Applications > Mining

Mining - “Harsh operating conditions”

The Mining Industry deploys an extensive variety of machinery, and encompasses machines that run over a wide range of speeds. A common scenario within the mining sector involves the monitoring of conveyors that are running at under 60Hz. In these situations a higher sensitivity, 500mV/g sensor (HS-100500 Series) can improve signal to noise ratios and increase your analysis capability if conducting full data analysis. Where 4-20mA (HS-420 Series) vibration sensors are deployed with the signal being interfaced with a PLC or similar system, a 0-25mm/s RMS velocity sensors (HS-420025 Series) is a great method for monitoring out of balance on fans and a 0-2g RMS acceleration 4-20mA sensor (HS-422002 Series) is good for providing protection on conveyors in between routing surveys.

Location
Whether the sensors are to be installed on a crusher, screen, conveyor pulley or drive generally a side exit/low profile model (HS-100S or HS-100MS Series) is advisable. If conditions permit top exit can be used, but location of the sensors may need to be looked at to make sure debris such as coal coming off a conveyor cannot damage the sensor. Some mining environments and parts of mines are suitable for installing top exit (HS-100 and HS-100M Series) sensors e.g. a pump room. In these areas it is good to use top exit units as they have a cost advantage over the side exit units. Another consideration if it is an underground coal mine is whether the units need to be IECEx certified for an intrinsically safe area? To get the best results the sensor should be mounted as close to the bearing as possible, in a stiff area of the housing (i.e. not on motor covers).

Environment
Mining is generally one of the harshest environments that accelerometers can be placed in. Armoured/braided cable is recommended for use in the majority of areas as it has the extra protection against cable damage. Generally 2 Pin MS connector sensors with separate IP66 2 Pin MS cable assemblies (e.g. HS-AC001) are a good idea as if there is an urgent shutdown it is much easier to undo a connector rather than dismount the whole sensor. There is also the advantage that in installations where there is a strong possibility of cables being damaged it is only the cable assembly rather than the sensor that will need to be replaced. This has to be weighed up with the initial cost advantage integral cable units have over connector units for which a separate cable assembly will need to be purchased. The minimum IP rating for mining should be IP65 and for parts of plant that have submersed assets IP68 units should be used (e.g.HS-1001000708). If vibration sensors are being used for routine data collection these should be terminated within an IP66 rated enclosure (HS-SE Series). It is also important to consider mounting options are suitable for the environment and installation techniques to ensure the best readings are obtained. Loose mounting or bad surface preparation will give rise to resonance or loss of high frequency data. (The use of magnetic mounts or spikes may reduce the high frequency signals, but this is unlikely to cause a significant problem when trending data). The accelerometer cable should be clamped to the body of the accelerometer with a cable tie to prevent strain and excessive movement of the cable to prevent false signals. The cable should also be fixed at suitable intervals to cable trays or other suitable supports.