KH Director just giving measurement of 4dkh!!!!

[Mortie31]

I’ve had my KH director for over 3 months and now I’ve got a new problem, 2 days ago it gave me a measurement of 4dkh and has continued to give this result in 8 subsequent measurements. My actual value is 7.5dkh as measured by my hanna. I have now flushed the cell, reagent line, emptied the chamber, recalibrated the ph probe and all dosing pumps and the waste pipe is not below the surface. The reagent bottle is full, there are no kinks or blockages in any lines. This is the last thing I need on top of 3 months of trying to get rid of bubbles in the reagent... and not trusting it enough to automate dosing.... any ideas before I take a hammer to this useless thing!!!!!!

[Matthias]

as in FB written:
If you have 8 measurements which all show the same value: This shows that the KHD works perfectly, it gets reproducable results. If ALL measurements have the same difference to the expected values than it looks very much like a wrong calibration of pumps or probe.

Please calibrate pH probe (again) and dosers. Post here the settings page of all involved pumps.
PS: I know you already calibrated, but please do it again, just to be sure.

And:
- You use a GHL Doser 2.1 for the KHD and not a Maxi, right?
- please post a picture of your complete KHD setup where I can see all details, connections, reagent, etc.

[Mortie31]

Hi Matthias as said above in my original post I have recalibrated everything, if the level hadn’t dropped from the usually measured 7.4 to 4.0 so quickly I wouldn’t of posted, and as I said in my original post the tanks dkh as measured by my hanna is 7.5dkh, so obviously there is an issue with the director. Since that post Overnight i have had readings of 7.6, 0 and 2.9 dkh so it is all over the place, dkh in a stable SPS doesn’t change by anything like these readings my usual swing is ±0.2 at most. I have flushed everything again and even changed reagent bottles this morning, so I will see if it is still wildly inaccurate when I get home. I will also send this into your support email to look into further.

[Mortie31]

Hello Matthias
I left my director measuring throughout the day as stated above, I'm now getting consistant readings of0dkh!!! Is this working perfectly??? ill send in to customer service now.

[WWIIIREEF]

Have you checked to make sure none of the dosing heads are sticking? Especially the water input. Hope they get it fixed up for you quick, I know you've had some issues with it before this as well.

[Mortie31]

Thanks, unfortunately it isn’t that, it’s now showing an error message of Titration took to long and constantly reading 0dkh, I’ve emailed ghl support and I’m sure they will sort it.

[Matthias]

This is under direct care of GHL.

We will post the news as soon as all has been sorted out.

[Stian Svendaen]

Hi, is there any fix for this? I have the exact same problem.

[Ian4302]

Having the same problem what was the solution to this

[Mortie31]

It was the internal circulation pump that had failed

[Mortie31]

If you have the latest GCC 1116 on the KHD page at the bottom you can see the ph readings, these should change as the reagent is added, during measurement. You should also be able to feel/see a vibration in the pipes during this as the circulation pump mixes the reagent and sample water. Mine did neither of these

[Ian4302]

Thanks for reply can i ask is the value of your probe continually moving when no regent is added mine goes from 3.5 to 4.3 when no thing is happening

[Mortie31]

Mine starts at 5.5 then rises to tank ph8.2 then drops quickly as soon as the reagent is added.. down to 6.5 after about 30secs and carries on dropping