Posted By Jeffrey Watt Kevin Not an answer but worthwhile reading into the effects of HFl at different concentrations, including severe ocular damage at concentrations over 0.5% http://ehs.unc.edu/pdf/H...20hydrofluoric%20acid%22 Depending on your process and vessel integrity or housekeeping you may get areas of leaks etc that can evaporatively become more concentrated e.g. solid crystals forming around spill zones. HFl is used in the semi industry to etch silica when making chips or read/write heads for hard drives. Someone with more day to day practical experience with it could maybe help. Kind regards Jeff

Posted By ddraigice I've no idea about this but I recall a story that my A level chemistry teacher told of when he was a safety officer for ICI (he was fantastic - we didn't learn much chemistry but his stories were great. He also looked like the flute playing guy in Jethro Tull). Very low concentrations were used by some company or other to etch glassware. The operators used to dunk the glass under the solution wearing rubber gloves and it was only at then end of a shift where one operator realised her glove had a tiny hole in the finger. And she only noticed that when her finger fell out of the glove. Nasty stuff.

Posted By Ron Hunter I've come across this sort of concentration in the form of "deletion pens" used in the printing industry. No particular issues other than use of gloves, overalls and an awareness on the part of employees on the irritant nature of the product, not to put these pens in their pockets, or lick the end whilst contemplating filling in their football pools in the mistaken belief they had an ordinary pen in their hand! The employer installed handy little pen-holders on the print machines in order to avoid confusion.

Posted By Jane Blunt You can download the medical handbook from one of the major manufacturers of HF at this address: http://www.honeywell.com...tes/sm/chemicals/hfacid/ At less than 1% the inhalation risk is negligible. The chemistry teacher who told the finger story was indulging in a bit of artistic licence - you don't suffer this kind of injury without it hurting. In fact HF burns are noted for being extremely painful, but the snag is that the pain may not appear for several hours. Nevertheless there have been cases of fatality from neglected pinholes in gloves. You should avoid all contact with HF as it is a very nasty systemic poison. I am not aware of any concentration limits below which calcium gluconate is not needed, so I would play it safe and have the stuff available. Jane

Posted By Jane Blunt HSE guidance on pickling pastes (including those containing HF) is here: http://www.hse.gov.uk/fo...h=%22pickling%20paste%22 Jane

Posted By Grahame Dunbar We use a software package for calculating the health/environmental classification of chemicals (SDS Professional). It says the following: 1.0% HF is Toxic and Corrosive Risk phrases R23/24/25 R34 R37 0.99% HF is Harmful (and Irritant) Risk phrases R20/21/22 R36/37/38 Hope this helps GD

Posted By John Lewis HF is the only acid that eats glass. We used it for etching. HF at low concentrations does not burn initially so if your process allows, mix it with another acid that does, that way you know if you have contacted the stuff. Teach your people about the material. Make them aware of just how dangerous it is. Keep a sink of bright red dye handy. Your operatives can wear plain white cotton gloves under their protective ones and put their hands in the dye for a few minutes. If the cotton glove goes red then the glove leaks; ditch it. Your local hospital will appreciate it if you have an "HF" first aid box to accompany any person exposed to the stuff. It helps them take the right action early on. First Aiders need to be aware of the stuff too. The last thing you want is cross contamination to the first aider as well. Finally, when we took our first delivery of 2tonnes me and a colleague cleared the area and taped it off. Then, from a distance we monitored the area while the techies dressed in chemical suits, carried out the task. Suddenly as if from nowhere a Japanese "engineer" appeared, opened the top of the storage tank and stuck his head in to make sure the acid was flowing!!!!!!!!!! Truly amazing. He was sent back to Japan the following week.