Compressed air, delivered by compressors 1, passes through air-pressure stabilizers 2 after which the stream of air is divided. A part passes through flow gauge 3 and the rest through conical valve 4. Then the air enters chamber 5 which has supplementary nozzles. The provision of these nozzles increases air flow through the glass tube of the flow gauge. From chamber 5 air flows to measuring head 6 whose stylus contacts the surface being checked. The surface irregularities vary the flow of air passing through the flow gauge and supporting the float indicator in suspension. The flow gauge scale is graduated according to surface finish standards.
$3714$SHP,M$