AFS Foundry Sand Testing Equipment Operating Instructions Manual

RIDSDALE-DIETERTMETHYLENE BLUE CLAY TESTER AND ULTRASONIC ACCESSORY (cont’d)IVTEST PROCEDURE (cont’d)(B)Total Live Clay Determination(a)(b)(c)(d)(e)(f)Take a representative sample of approximately 15 g of the system sand to betested. Remove any contaminants and dry the sample to constant weight in amoisture teller or drying oven.Weight out a 5.00 g sample for the methylene blue total clay test and transferto one of the 250 ml stainless steel beakers. Add 50 ml of 2% tetrasodiumpyrophosphate solution via the repeating pipettor by tilting it until the liquid fillsthe upper receptacle and spills over into the measuring tube, filling it to the 50ml drain edge, then tilting it the other way to drain the 50 ml into the stainlesssteel beaker. Slip an “O” ring up over the beaker so that its top is located ¾”(19 mm) below the bottom of the flared section.Transfer the beaker to the Ultrasonic Accessory. Slip the beaker downthrough the central opening in the cover which should position the beaker sothat approximately 0.4” (10 mm) is submerged. The water level should beapproximately 1¾” (43 mm) above the bottom of the tank.Switch on the Ultrasonic Accessory and allow to operate for 5 minutes.Remove the beaker, and carry out the methylene blue titration procedure inthe same manner as described in the “determination of calibration factor”procedure above (Sections A(e) to A(j)).The total live clay is calculated by dividing the number of ml of methylene blueto reach end point by the calibration factor (as in A above).(C)Dispersed Live Clay Determinations(a)(b)(c)In a system sand not all of the clay present is in the proper form to contributestrength to the mix. Some of the clay is present in lumps, or colonies, andmay be entrapped by other additives. For maximum strength the clay shouldbe thoroughly dispersed and completed distributed over the grains. This isseldom the case. There is usually a difference between the total amount ofclay present and the dispersed and working clay, ie, the clay that is in theproper form to contribute to the strength of a mould.The process for determining this dispersed live clay is exactly the same as fortotal live clay as described in B above, except that the Ultrasonic Accessory isnot used at all. Thus the procedure is exactly the same as per B aboveexcept that instead of carrying out the instructions per B(c) and B(d) thecontents of the stainless steel beaker are merely stirred for 2 minutes prior tomethylene blue titration.The dispersed live clay is calculated by dividing the number of ml ofmethylene blue to reach end point by this means by the calibration factor (asin A above).10