A laboratory equipment manufacturer contacted us after an incident with a high temperature combustion reactor. An Fe (Iron) Scrubber is used to extract acid from air using iron. The oxygen level using in the extraction process is very high. The system assembly is such that 12 nitrile O rings require lubrication to avoid distortion/warping during equipment assembly.
The customer had lubricated with a silicone grease but this had caused an explosion due to the chemical reaction with the high level of oxygen and the carbon content in the silicone grease.
Any new grease proposed should have a very low or zero carbon content and be classed as inert so that it does not react with the high level of oxygen. The chosen grease should also be considered a low outgassing product so that there is no potential contamination of the equipment. The proposed grease is also expected to have an upper working temperature of 250°C
- A Perfluoropolyether (PFPE) based grease does have a carbon backbone but is considered low carbon. PFPE’s are made up of only Carbon, Oxygen and Fluorine making a PFPE extremely resistant to reactions, including combustion; PFPE oil is therefore considered inert and should not react with the high level of oxygen.
- The grease should be thickened with Polytetrafluoroethylene (PTFE) as this will help with the O ring lubrication and PTFE is also inert.
- The low outgassing characteristic of PFPE is ideal to help avoid any issues related to the performance of the Fe Scrubber.
- A PFPE based grease can cope with the extreme working temperature involved, which is 250°C.
Applying The Grease
A thin layer of Uniflor 8511 is applied to the 12 O rings in each Fe Scrubber.
The Uniflor 8511 lubricated the O rings successfully and eliminated the risk of explosion during Fe Scrubber operation.
Uniflor 8511 successfully eliminated the risk of explosion during device operation.