Application of optical streak sensors in air+oil lubrication systems
Sensors can be mounted in retrofit procedures in order to verify the working of the air+oil mixers that have been previously installed. In this case they are mounted directly at mixer outlet.
Please consider that in this case the sensor controls a flow that is never steady because the lubricant dosing, in single-line systems, takes place cyclically at timed pulses.
So we have to distinguish between a dynamic type control (signal at every lubrication cycle) or static control (signal nearly uninterrupted).
We have the following options:
- Dynamic control: with sensor type IFX-S08 mounted inside the mixer (MVF-AX)
- Dynamic control: when the sensor (type IFX-C04 or C06) is outside the mixer, but at a distance of max. 10 cm.
- Static control: when the sensor (type IFX-C04 or C06) is outside the mixer and it is positioned to a distance of more than 1 mt.
In cases 1 and 2 the sensor will respond changing the status (LED green and then red) at every lubrication cycle, advising that the lubricant dosing took place properly. In case 3, the signal (green LED) is always on, provided that the lubricant flow rate (the oil streak) is enough and uninterrupted: for example, with a sensor positioned at 3 mt. from the mixer and a lubricant volume of at least 300 mm3/h, with an air flow not higher than 50 Nl/min.
A lower quantity of lubricant volume, or a higher air flow rate, can cause an unstable signal owing to a too limited and irregular flow for the optics of the sensor, but however valid for the needs of the lubrication point. This must be taken into consideration reasonably in the signal control management.
On the basis of the experience consolidated in the practical field, it is preferable to recommend a dynamic control, since this type of control is independent from the dosed volume and guarantees the control of every single cycle (“miss shot”).
The static control is used as redundant control, as guarantee of the lubricant presence in the final part of the pipes (see also video clip “redundant sensor”)
Related products:
Optical sensor IFX-C
Optical sensor IFX-S
Air-oil mixer MVF-AX