Hello all. I am looking for some advice with a DI application.
We have a process that includes quenching small metal parts. The quench solution contains a sodium nitrite inhibitor that provides corrosion protection. We purchase DI water in tanks from a local water treatment supplier. In order to maintain the correct nitrite level in our tank, I use a simple Myron analog conductivity meter to measure the conductivity daily and adjust the quench solution as necessary. Everything was going along fine until my last shipment of DI tanks. Although the green “OK” light was lit on the tanks, the conductivity readings right from the DI tank were off the scale on my meter - over 10,000 microhos when normally I get around 20. The supplier said it wasn’t possible and told me it was my meter. I went to two other DI tanks we have on other processes at our facility and each gave me a reading of under 20 microhos.
The supplier came over and used his resistivity meter and could not get an accurate reading but said that since the light was green they were fine to use. I disagreed and he did end up replacing the tanks.
I also perform chloride checks from time to time and discovered that the chlorides in the process tanks were very high during this same time frame – over 630 ppm in the process tank when normal readings are under 30 ppm. The supplier said the tanks may have been used in a water softener application previously and were not rinsed before filling with new resin?
My questions are: why would the DI indicator lamp give a green OK when the conductivity readings were so high? Is it normal to use the same tanks for water softener and DI applications?
Thanks for any help you can offer.
We have a process that includes quenching small metal parts. The quench solution contains a sodium nitrite inhibitor that provides corrosion protection. We purchase DI water in tanks from a local water treatment supplier. In order to maintain the correct nitrite level in our tank, I use a simple Myron analog conductivity meter to measure the conductivity daily and adjust the quench solution as necessary. Everything was going along fine until my last shipment of DI tanks. Although the green “OK” light was lit on the tanks, the conductivity readings right from the DI tank were off the scale on my meter - over 10,000 microhos when normally I get around 20. The supplier said it wasn’t possible and told me it was my meter. I went to two other DI tanks we have on other processes at our facility and each gave me a reading of under 20 microhos.
The supplier came over and used his resistivity meter and could not get an accurate reading but said that since the light was green they were fine to use. I disagreed and he did end up replacing the tanks.
I also perform chloride checks from time to time and discovered that the chlorides in the process tanks were very high during this same time frame – over 630 ppm in the process tank when normal readings are under 30 ppm. The supplier said the tanks may have been used in a water softener application previously and were not rinsed before filling with new resin?
My questions are: why would the DI indicator lamp give a green OK when the conductivity readings were so high? Is it normal to use the same tanks for water softener and DI applications?
Thanks for any help you can offer.
