THE BALANCED SEALS HAVE A LOWER BALANCE RATIO AND CAN WITHSTAND PRESSURE UPTO 600 PSIG.
              THE LATEST EDITION OF API 610, IRRESPECTIVE OF THE PUMPAGE PRESSURE OR THE STUFFING BOX PRESSURE, SPECIFIES USE OF BALANCED MECHANICAL SEALS, IN GENERAL.
                                    3.SPEED
             SPEED IS THE MOST DIFFICULT FACTOR TO HANDLE AND HAS A STRONG EFFECT ON THE PERFORMANCE OF THE MECHANICAL SEALS. AS THE SPEED OF A MECHANICAL SEAL GETS HIGHER AND HIGHER, THERE ARE GREATER CHANCES OF THE SEAL RUNNING DRY. THIS WILL GIVE RISE TO HIGH INSTANTANEOUS TEMPERATURE DUE TO PHYSICAL CONTACT. THUS SEAL FACES CAN GET DEFORMED OR CRACKED DUE TO THERMAL SHOCK. MOREOVER, THE LIQUID MAY CHANGE ITS PROPERTIES OR PHASE DUE TO EXCESSIVE HEATING CAUSING AN IMMEDIATE SEAL FAILURE.
              TO AVOID THIS TO HAPPEN, IT IS NECESSARY TO PROVIDE FLUSHING ARRANGEMENT TO COOL THE SEAL FACES AND MAINTAIN A THIN STABLE LUBRICATING FILM BETWEEN THE SEAL FACES.
IT IS QUITE COMMON TO USE RIGIDLY MOUNTED ROTATING FACES FOR HIGHER SPEEDS. THE SPRING ASSEMBLY IS KEPT STATIONARY TO AVOID EXCESSIVE VIBRATION.
                         SPEED - PV FACTOR
              IT IS AN ARBITRARY MATHEMATICAL EXPRESSION USED TO EVALUATE THE SEVERITY OF A PROCESS APPLICATION. IT IS THE PRODUCT OF SEAL FACE PRESSURE AND A LINER RUBBING VELOCITY OF A MECHANICAL SEAL.THE SEAL FACE PRESSURE IS CALCULATED USINGTHISFORMULA. 

P FACE   = P BOX x BALANCE RATIO
PV	        = P FACE x V LINER (KG/CM2) x (MTS/SEC)