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Pasteurizer holding time test and certification

Verification Certificate provided on completion of test

**A Holding Time Calculation**

In calculating the holding time for the holding section of a pasteurizer, the flow conditions existing in the holding section are taken into account by calculating the Reynolds Number of the product in the holding section at the heat treatment temperature.

Reynolds Number, Re = ρvD/μ

**where:**

ρ = density, kg/m^{3}

v = velocity of flow, m/s

D = diameter, m

μ = viscosity of produce at the heat treatment temperature, Pa s

ρ = density, kg/m

v = velocity of flow, m/s

D = diameter, m

μ = viscosity of produce at the heat treatment temperature, Pa s

Laminar flow is assumed when the Reynolds number is less than 4000. For laminar flow, the holding time is calculated by assuming that the maximum velocity is twice the average velocity based on the maximum flow rate.

Turbulent flow is assumed where the Reynolds number exceeds 4000. For turbulent flow, the holding time is calculated from the actual measured fastest particle velocity based on the maximum flow rate. As the ratio of maximum velocity varies with Reynolds number it is recommended that the design is reviewed by a heat treatment validator or evaluator. As an initial guide for turbulent flow, the maximum velocity may be assumed to be 1.33 times the average velocity for Reynolds number=4000, and 1.25 times the average velocity when the Reynolds number exceeds 20000.

**DUE DILIGENCE - Do you comply with the legal requirements?**

PASTEURISER HOLDING TIME TEST - DUE DILIGENCE COMPLIANCE

See Pasteurizer operating requirements

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