Some chart recorders come with a glass covering to accompany their top cover/door. Window glass provides a second layer of protection to the chart recorder’s internal mechanisms. Glass directly protects the chart paper, pen/stylus, and recorder arm. Window glass is a significant chart recorder part because possesses the potential to enhance the graph-reading experience or hinder it greatly.
Quality glass, which is both clear and an appropriate thickness for accurate reading purposes, is required for effective readings on a chart. Some chart recording devices are equipped with plastic windows. Although these are usable, they are certainly not preferable. Much like a thin plastic top cover provides less protection than a solid, metal top cover, a glass window that is reinforced in the way a car window is provides a higher standard of protection.
Despite its increased degree of protection, glass windows are susceptible to damage. User errors and mistreatment, like dropping the chart recording device, can cause cracks in the glass. Allowing the device to be cleaned in an inappropriate manner can result in tiny scratches on the surface of the material. Chart recorders that are left unattended and exposed to inclement weather, or drastic shifts in temperature, are also susceptible to cause glass damage.
Damaged window glass on any paper-driven chart recorder can be replaced in the same way the top cover/door can be replaced. However certain paperless chart recorders that mimic computer monitors may require a technician’s assistance to replace, as it could entail disassembling the system’s face.