Section 892.1820 - Pneumoencephalographic chair(a)Identification. A pneumoencephalographic chair is a chair intended to support and position a patient during pneumoencephalography (x-ray imaging of the brain).(b)Classification. Class II (special controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 892.9 .48 FR 53047, Nov. 23, 1983, as amended at 84 FR 71819 , Dec. 30, 2019