KHD measure with ALK/dKH reference solution

[osanchezmon]

Dear support team,

I did two measures with the GHL ALK/dKH reference solution (7.5 °dKH) and results were 7.9 and 8.0. The tolerance of the solutions is +/- 0.2 °dKH. Probe and doser pump were calibrated before the measures.

Could you please tell to me the reason of this values? Is the KHD working bad?

Thanks in advance.

Regards,
Oscar Sánchez.

[Vinny]

Hello Oscar,

The correct tolerance when using the KHD and Reference solution is +/- 0.4° dkH (0.2 from KHD and 0.2 from Reference solution).
Given your results, you are within the tolerance range.

If you would like to get the KHD result a bit closer to the 7.5 mark, check again your tube lengths and calibrate your pump heads. When calibrating pump heads, you can use a digital scale to get the most precise measurement; 1g = 1mL

You can also verify your water sample tube volume by temporarily disconnecting the tube going into the KHD and manually filling both ends of the tube. Empty this tube into a digital scale or measuring cup and type-in the amount into the tube volume field in the KHD settings page.

[osanchezmon]

Thanks Vinny for the tips! I will apply it to get a more accurated result!

[JBellaiche]

Vinny,

When you do this, should you remove the filter?
And do you have to add the 11.9 mm length of tubing in the pump and filter volume ?

[Vinny]

You don't have to remove the filter. Leave it installed.

Yes, all parts of the water sample tubing must be taken into account before you enter the total length.