Air is pumped by rubber bulb 1 through water-type air-pressure stabilizer 2, maintaining a constant pressure of compressed air, to orifice 3 through which it enters chamber 4. Secured on rubber membrane 5 in the chamber is steel nozzle 6 with a bevelled lower edge and carefully lapped end face. Spring 7 holds nozzle 6 against the surface of the glass being checked. A weight is placed on the top of head 8 to be sure the face of the nozzle tightly contacts the glass. The pressure in the head chamber is an indication of the size and form of surface irregularities and is read off on manometer 9, connected to the chamber. The manometer scale is graduated according to glass surface finish standards.
$3712$SHP,M$