LumaSense Technologies M67 - Manual (Page 25)

M67, M67S Manual
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Figure 17 - Suggested Piping When Using Air Purge Assembly
7.5 Air purge assembly
This assembly performs three very important functions: purging, aiming and localized cooling. Air purging of the optical
devices located within the INFRADUCER is extremely important if airborne contaminants are likely to deposit gradually on the
lens, eventually “blinding” the instrument. A flow of 25 to 150 ft 3 /hr of dry, oil-free air will normally be required to ensure a
clean lens. Industrial, clean air will usually suffice for this purpose.
A good air purge supply system consists of an automatic drain filter to trap any oil and condensed moisture, a microfilter to
remove dust particles, a pressure regulator and a flow indicator (such as a rotameter)
It is also important to note that the purge air supply rate may need to be monitored closely when long sight tubes which end
close to very hot targets (e.g., molten metal, liquid glass) are in use. Excessive purge air flows could cause surface film
oxidation or premature chilling.
It is very important to ensure that the coolant supply temperature (assuming coolant is used) is above the dew point of the air
used in the purge assembly.
Mounting details for the Air Purge Assembly are shown in Figure 18. (Details for connecting the coolant piping are shown in
Figure 17). Note that the Air Purge Assembly contains two Sections: an air purge chamber and a separate, water cooled block,
which provides additional cooling at the front flange. A single 1/8" NPT connection is provided for the purging air supply to
the Air Purge Assembly.