Diaphragm-seal packless valve 

1/4 in. NPTM threads. Diffusion and corrosion resistant. KEL-F valve seats for positive shut-off. Low rms internal finish. Body stamped with heat code for material traceability. For purity assurance, poly-bagged after electropolishing and ultrasonic cleaning. Low leak rates: <2 × 10^-8 scc/s He. Pressure range: vacuum to 3,000 psig.