Liquid Transfer Grounding Problem
I have a process where I take 1 stainless tank with corn oil (and other stuff I can't say and should not make a difference) hook a nitrogen line to it at 10psi then hook the tank to a stainless filter connected to a stainless roller table and hook that to an empty identical stainless tank. See picture. The hoses are clear silicone diamond cured.
We ran into a problem. While doing the transfer static electricity was building up and sparking was happening between the receiving tank (empty tank being filled) and the connected hose. There was also sparking happening at the filter table and that hose.
No sparking was detected at the starting tank.
We bonded the tanks and filter and connected them to a grounding plate. The grounding plate was checked with an ohm meter. the sparking still happened.
We have done this for over 5 years and never had this happen. This is our first time using corn oil. We usually use coconut oil.
Any thoughts?
Comments (7)
Have you checked your bonding cable for resistance (ohms)? If there's not good continuity of the bonding cable, it won't effectively ground the 2nd container.
The grounding and bonding only address the static potential of the transfer hose itself. If there's any air gaps (e.g., bubbles) in the corn oil due to the nitrogen, there can still be a static potential.
What’s the difference in viscosity for the two at STP? That should be on the SDS.
Alright, we got it! So, corn oil is 1 of the most non-conductive oil you can work with. It is passed through a nonconductive filter with several parts and layers. We eliminated the hose on the right by connecting the filter straight to the tank. This gave ground to the filter through the tank. We also cut the hose on the left in half, put a steel sanitary fitting in between, and grounded that. We halved the pressure the push. There is 1 more thing we could have done but did not: heat the corn oil mixture beforehand. Hope this helps someone.