MKS Granville Phillips 274, Iridium Filament, Bayard-Alpert , 3/4 in. Pyrex Port, Glass Ion Vacuum Gauge. PN: 274002

These MKS Granville Phillips 274 Iridium glass ion gauge tubes have a 3/4 inch OD vacuum connection Pyrex Glass port and an operating range from 1x10^-3 to 2x10^-10 Torr. These ion gauge tubes are compatible with most modern hot cathode ion gauge tubes. They have a sensitivity of 10 Torr-1 and standard operating voltages (collector 0 VDC, Grid +180 VDC, filament -30 VDC with 5 VAC).

The MKS Granville Phillips thoria coated iridium (IR) filament configuration can be used in any clean application, but is particularly practical in potentially oxygen rich environments. All IR filaments have a thoria coating, which increases electron emission to approximately the same level as tungsten filaments. Iridium filaments, however, can be strongly degraded by metallic or organic contaminants, resulting in poor accuracy (filaments are easily poisoned by oil back-streaming from diffusion or mechanical vacuum pumps). Thoria coated IR is very resistant to oxidation, and can even tolerate brief exposure to atmosphere during operation and will not damage or shorten the filament life.

Iridium ion gauge tubes can be typically identified by the single white "hair-pin" shaped filaments and have four external leads at the plug end. This MKS Granville Phillips gauge tube works with most hot cathode ion gauge controllers made by MKS Granville Phillips, MKS Instruments, Perkin Elmer, Varian, & Veeco.