Hello Rodney,
I am not sure if you are using water, oil or polymer as the quenching medium. In any case, a stable quenching performance requires constant monitoring of the quenching medium. I would recommend that you contact your quenching medium supplier and ask them for procedure and controls to maintain stability of the medium. The attached link from Fuchs contains a nice summary procedures used and tests for quench tank monitoring:
https://www.fuchs.com/fileadmin/schmierstoffe/Prospekte/Brochures_EN/Product_brochures_industry/Quenchants_Monitoring_and_Maintenance.pdf
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[Ratnesh] [Dwivedi]
[President]
[RKD ENGG, LLC]
www.rkdengg.com------------------------------