According to the National Institute for Occupational Safety and Health (NIOSH) worker safety can be compromised by using replacement component parts or accessories that are not NIOSH-approved for the specific respirator.
Although NIOSH-approved respirators are comprised of various component parts, they are approved as a complete unit. The use of components which are not part of the approved assembly results in a respirator that has not been evaluated and certified by NIOSH.
This applies not only to parts supplied by other vendors, but also to those supplied by the original equipment manufacturer, if the component parts have not been evaluated