Double mechanical seals are used as leakage proof sealing solutions for mixers or pumps while handing toxic media. These mechanical seals comprise of two primary seals and a buffer fluid passage located between these seals. Primary seals contain narrow and soft stationary face and a relatively wider and harder face that can be rotated. This design proves to be useful to resist wear of harder faced seal. Double mechanical seals are equipped with TTV/viton/FEP elastomer, TC and SiC seat face and SiC and carbon made seal ring faces. These seals can be used at maximum 10 bar operating pressure and at up to 200 degree C working temperature.