Perkin-Elmer Bayard-Alpert High Vacuum Gauge w/ 2.75 CF to KF40 Adapter DN40CF

Perkin-Elmer Bayard-Alpert Type Hot Cathode High Vacuum Gauge.

Perken-Elmer Vacuum Products Model number 605-7152

Is connected to a standard KF connection by a high vacuum fitting.

Bayard-Alpert ion gauges have a reasonably linear response from 1e-9 to 1e-4 Torr, with gauge sensitivities from 5 to 20 Torr-1. Bayard-Alpert gauges are available with one or two filaments (the second acting as a spare) and with two filament materials thoria-coated iridium, used in oxygen-rich applications and for 'burn-out' protection if accidentally vented and tungsten, used for lower cost and in residual gases containing halogens.

The standard Bayard-Alpert gauge measures down to 1e-9 Torr. It does not go lower because primary electrons generate soft X-rays when they hit the grid. An X-ray hitting the ion collector electrode releases a photo-electron, which is indistinguishable from positive ions arriving there. Below 1e-9 Torr, photo-electron emission is a large enough fraction of the ion current to distort the pressure readings.

Condition is Used.