The Possible Formation of Hydrogen Fluoride From the Reaction of Silicon Tetrafluoride With Humid AIr

Hydrogen fluoride (HF) has been considered a hydrolysis product from the reaction of silicon tetrafluoride (SiF4) and water. This has caused concern for potential human exposure to HF. A SiF4 release (20 ppm nominal) was simulated at three different humidity levels inside a test chamber in order to determine if HF is formed. Dilute SiF4 was blended with dry and/or water-humidified air at ambient temperature. Air samples at each humidity level were collected using a Teflon® filter followed by an impinger containing an absorbing solution. The filters and impinger solutions were analyzed for total silicon, using Inductively Coupled Plasma Emission Spectroscopy, and total fluoride by Ion Specific Electrode. By comparing the ratio of silicon to fluoride in each of the samples it was determined that HF was not produced in significant amounts at any of the humidity levels tested.