7032M for TDS measurement

[postenje]

Roger, I have a 7032M conductivity meter. Is the 600us calibration fluid low enough to calibrate the unit for accurate TDS detection on my RO unit? The only other calibration fluid I have on hand is the 50ms.

Thanks

Jeff

 

[rvitko]

You will want to always calibrate both and yes it will work for RO/DI water. Be sure and soak the electrode in RO water for 24 hrs- then procede with 600us then rinse in RO then procede with 50ms calibration. The slight amount of salt soaked into the graphite electrode will skew calibration if you do otherwise.

 

[postenje]

I have been using it to measure my salinity continuously since mid november. I have cleaned and calibrated it a few times in this period. I wanted to start measuring the TDS of the RO output to see if DI is needed. What would be the best procedure / steps to take?

Soak in cleaning solution for a couple hours and scrub thoroughly.

then

Calibrate to 600us

then

calibrate to 50ms

Thanks for all the help.

jeff

 

[rvitko]

Follow the procedure I outlined above after the cleaning- calibration always involves both fluids.

 

[postenje]

Roger,

One other question. Am I going to have to soak in RO and recalibrate every time I transfer the probe from my sump to a cup of RO to check for TDS?

Jeff

 

[rvitko]

Yes, because the probe is a soft graphite material it retains salt. It is not that it makes an incredible difference but i would expect to be off by about 100us if you don't. Sorry for the terse answer before Jeff, my computer was being goofy- today was update day and the UPS software crashed the system and of coarse UPS said it was a microsoft problem and microsoft said it was a UPS problem. Thank god for system restore. Sorry about being a butt.

 

[rvitko]

Actually recalibration won't be necessary- just the soaking- recalibration is something you should do every 3-4 months. Sorry didn't catch that- still frustrated.

 

[postenje]

No worries Roger.

I think I'm gonna buy a TDS meter for my RO. "Cleansing" for 24hrs everytime I want to check TDS sounds like a chore.

Can you recommend a quality inline meter?

Thanks for all the help.


Jeff

 

[rvitko]

Just get the little Spectrapure Water quality monitor- it is about $60. It taps in line and you set a switch for one of three settings and when that level of conductivity is exceeded an LED comes on. It is very simple but it does the job and is reliable. Also, you could try one of those cheap little Milwaukee units- the little pocket checker type. I don't like them for much but for testing DI water I don't see a problem, their is nothing corrosive to eat at the electrodes so stainless steel is fine and while they can't be calibrated, for the money- also about $60- they do a good enough job.