This high-vacuum valve is for use in vacuum applications up to 5 x 10-7 Torr. It is similar to 826510 series but without tip o-ring exposure. Designed with a precision external thread for fine control. Can be used as a bleed up to 1/2 turn. Full open position is at 1-1/2 turns. The primary seal is made with a FKM o-ring on a tapered seat. Non-rotating PTFE shaft can be used continuously at system temperatures of 230°C or intermittently at 275°C. Manufactured from 33 expansion, low extractable borosilicate glass conforming to USP Type I and ASTM E438, Type I, Class A requirements.