Valve verification will use a connected balance onto which the D2 will dispense. Make sure the liquid container has enough volume so it does not over flow! You can specify the total number of shots and the number of shots between reading the balance, this is useful in cases of very low dispense volume where each shot could be under the value at which the balance can detect. Use a balance with at least 0.1mg scale ideally and ensure that the measurements are stable, draft free and that the balance is accurate/calibrated!