AFS Foundry Sand Testing Equipment Operating Instructions Manual

RIDSDALE-DIETERT ELECTRIC PERMMETER (cont’d)VCALIBRATION AND MAINTENANCE (cont’d)If the instrument appears to be out of calibration, blow out the calibrated orifices with clean,dry compressed air.NEVER CLEAN ORIFICES WITH METAL POINT OR WIRENOTE:The check jets are not interchangeable and must only be used on the instrument with whichthey are supplied – see instrument serial number stamped on jet.If adjustment is required to obtain the necessary 100 mm air pressure, carry out the followingprocedure :-(a)(b)(c)(d)(e)Switch on blower motor.Place lever in check position.Set rheostat in mid-way position of total travel.Remove hex plug positioned on the top of the machine to right-hand side of thecentre post, to gain access (see (e)).Slacken off 2BA brass nut using box spanner, pass screwdriver down through thecentre of the box spanner and turn screwed spindle in a clockwise direction till 100mm reading is obtained. Retighten the locknut and replace hex plug.Tools required – 2 BA Box Spanner and instrument screwdriver sufficiently long toprotrude through the centre of the box spanner.NOTE:Adjusting the air pressure does not affect the calibration of this instrument.VIRECOMMENDED SPARESPart No.Description2201 ‘O’ Ring – sealing – centre post2202 ‘O’ Ring – cushion – centre post2205 Sealing washer - orifice2206 Pressure gauge.71