Is it necessary to exposure sampling points to flame before take the sample
No, it is not necessary. You must flush the sampling point for about 1 minute.
Additionally IPA can be sprayed before sampling
No,a open the tap for few min. After rinse the bottle with water and collect the sample.
sujatha was told correctly we are also following the same.
Before collecting the sample 2-3 minutes drain
it s based on your drain study.