Knowby Dairy Systems EN English (EN)Filipino (TL)Spanish (ES)Hindi (HI)Portuguese (Brazil) (PT) Vat milk sample for PCR 1 Step 1 of 4 Ensure the vat is agitated. 2 Step 2 of 4Open the tap and let milk run for 10 seconds. 3 Step 3 of 4 Now collect your sample. 4 Step 4 of 4Ensure milk is taken from every vat if there is more than one.