I am looking for a procedure to disinfect a potable stainless steel water supply system in a food grade plant under new construction. Could you please refer a standard to follow?
A standard disinfection procedure (as set forth by AWWA) is to inject 50 to 100 PPM of chlorine as the water is flushed throughout the pipes and fixtures. Confirm that the chlorine residual is at least 50 PPM from each fixture and then shut off the water. Let the water sit in the pipes and fixtures for 24 hours. After 24 hours, if the chlorine level is less than 10 PPM, then the procedure is repeated, otherwise, at that point the plant is flushed with clean water and is considered sanitized.
See this link for more information on the AWWA standard:
Some contractors will use the “slug method” and dump in chlorine pellets or powder, but its far better to make sure that all fixtures have 50 PPM and let the pipes sit for 24 hours and retest. Fortunately this is easy to with a metering pump, and high-level chlorine test kit.
For this procedure we recommend a chlorine injection pump and a high-level chlorine test kit:
For example, this pump here could inject 50 PPM chlorine into water flowing in the pipes, from 2 to 50 GPM
85MHP40 Pump 2.0-40.0 GPD 120V
Maximum line pressure 100 PSI
Here is a good test kit to use:
Hach Chlorine Total Chlorine 10-200 ppm 100 Test