OT (Operation Theater) HEPA module is installed in critical area of hospitals.  OT Plenum is fitted with HEPA filter to control the particle contamination by passing the air in same direction with a same speed to avoid the turbulent and swirls in Operation Theater. In this OT HEPA module air enters through AHU and drops the air through the HEPA filters installed in the plenum, 99.997% particle and contamination free air passed vertically downwards the work surface and leaves the cabinet sweeping out particles and bacteria.