This technique is based on the fact that if apulse of tracer (a dye) is injected to the flow, a decayings inusoidal type of response is detected at the downstream of the injection point. Tracer was injected to the gas–liquid separating section.
Values of optical density were recorded in a spectrophotometer until the response of the pulse was completelydamped. There after, mixing time was determined by changing L/D, separator volume, UsG and UsL.