In the majority of cases it is best to have a direct path of radiation from the UV lamp to the target area to maximise the curing effect. However, in some cases, the application necessitates a quartz glass filter to be installed in the lamp’s emitting window.
This can be for a number of reasons:
- To filter out infra-red (IR) radiation from the UV lamp when processing heat sensitive substrates.
- To stop the substrate being sucked into contact with the lamp.
- To prevent airborne contamination from passing over the lamp and reflectors.
- To avoid spilt ink or varnish from running down the web and into the UV lamphead, when the lamp is installed below a chill roller.
- To ensure the correct airflow path through the UV lamphead when the system is fitted with a Positive Purge or Net Zero cooling system.
- On inert gas curing systems, sealed quartz windows are used to contain the inert gas, typically nitrogen, in a chamber beneath the UV lamp. The level of residual oxygen in the chamber can then be controlled down to very low levels, independently from the flow of cooling air through the lamphead on the other side of the quartz window.
In these instances, a flat section of quartz glass is fitted over the light emitting window to enable a broad spectrum of UV energy to pass through, whilst blocking air movements and IR radiation.
For specialist applications where high doses of UVC energy are critical, GEW’s HiC quartz windows can be specified. These are transmissive to an even broader spectrum of UV energy than standard quartz windows, with transmission in the UVC band especially enhanced.
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If you would like to know more about this customisation option, we are here to help. Please contact the sales representative that is best placed for your region.