A PURIFIER MAKES USE OF THE SPECIFIC GRAVITY DIFFERENCE BETWEEN MIXED LIQUIDS. BUT IT IS IMPOSSIBLE TO CHANGE THE POSITION OF INTERFACE OF LIGHT AND HEAVY LIQUID DUE TO ITS STRUCTURE. HENCE, PURIFIER MUST BE USED BY ADJUSTING THE OUTLET POSITION AT LIGHT OR HEAVY LIQUID SIDE ACCORDING TO THE SPECIFIC GRAVITY DIFFERENCE BETWEEN MIXED LIQUIDS, SO THAT THE INTERFACE OF LIGHT AND HEAVY LIQUIDS MAY LOCATE AT THE FIXED POSITION INSIDE THE BOWL. THIS WORK IS CARRIED OUT BY GRAVITY DISC.
IN ORDER TO UNDERSTAND IT EASILY, LETS CONSIDER ABOUT A U-TUBE IN THE GRAVITY HAVING WATER. NOW WHEN OIL IS SUPPLIED THROUGH OPENING “b”, AS SPECIFIC GRAVITY OF OIL IS LESS THAN THAT OF WATER, THE LEVELS OF OIL AND WATER WILL BE DIFFERENT AS SHOWN IN OTHER FIGURE.
LET CALL THE LEVEL OF WATER AND OIL FROM THE INTERFACE LINE O-O OF BOTH LIQUIDS AS h(w) AND h(o) AND THE SPECIFIC GRAVITY OF WATER AND OIL AS ¶(w) AND ¶(o) RESPECTIVELY.THE IT WILL BE AS THE FOLLOWING EQUATION :
¶(o)h(o)=¶(w)h(w)
(¶(o)/¶(w))=(h(w)/h(o)
NOW IN THE FIGURE BELOW AN INLET FOR SUPPLYING MIXED LIQUIDS SHALL BE INSTALLED AT O-O AND FURTHERMORE OUTLETS AS SHOWN IN ABOVE FIGURE BY DOTTED LINE ON OIL AND WATER FACE ARE INSTALLED RESPECTIVELY.
NOW IF WATER ONLY IS FED FROM POSITION “O” THEN ONLY WATER WILL COME OUT FROM THE WATER SIDE OUTLET AND IN CASE ONLY OIL IS FED THEN ONLY OIL WILL COME OUT FROM THE OIL SIDE OUTLET. THE INTERFACE O-O WILL NOT VARY.
FURTHER MORE , IT IS EASILY PROVED THAT IF THE MIXTURE OF WATER AND OIL IS FED FROM THE POSITION “O”, IRRESPECTIVE OF ITS MIXTURE RATIO, OIL AND WATER WILL FLOW OUT FROM THEIR RESPECTIVE SIDE AND INTERFACE WILL NOT BE EFFECTIVE.
NOW LET US LAY THIS U TUBE HORIZONTALLY AND HAVE A CENTRIFUGAL FORCE ACT ON IT INSTEAD OF GRAVITY, THE RELATION BETWEEN THE WATER AND OIL WILL REMAIN THE SAME. HOWEVER, IN CASE OF CENTRIFUGAL FORCE, THE EQUATION BECOMES:
(¶(o)/¶(w))=(D^2-d(w)^2)/(D^2-d(o)^2)
IN CASE OF CENTRIFUGAL FORCE, THE LINE O-O IS FORMED AT POSITION D DECIDED BY ROTATION. AND THE HEIGHTS h(w) AND h(o) ARE SUBSTITUTED FOR THE DIFFERENCES OF THE HEIGHT OF LINE D AND THE HEIGHTS OF EACH OUTLET AS SHOWN IN EQUATION ABOVE.
THE LAST FIGURE SHOWS THE CASE OF PURIFIER BOWL. EITHER d(o),d(w) OR D NEEDS TO BE ADJUSTED BY THE SPECIFIC GRAVITY OF LIQUID TO BE TREATED, BUT GENERALLY IN CASE OF A PURIFIER AS D AND d(o) ARE FIXED, ADJUSTMENT MUST BE MADE BY d(w) TO THE SPECIFIC GRAVITY OF LIQUID TO BE TREATED. IN ORDER TO CHANGE d(w), PURIFIER HAS SUCH A STRUCTURE THAT DISCS OF SEVERAL DIFFERENT INSIDE DIAMETER CAN BE INSTALLED IN BOWL. THIS IS CALLED AS A GRAVITY DISC.