Dangers of hydro fluoric acid HF

Recently, I had an interaction with some persons in a training programme. During the discussion, a person narrated his experience with HF handling three decades ago.

The person was asked to take a plastic bottle from one place to another. He held the bottle at the top and it crumbled and in the process, he had splashing of some contents on his thumb. Not knowing what it is, he washed and continued his work. Later, in the evening he had swelling and pain for which he consulted the doctor.

On enquiry, it came out that the bottle contained some HF.

After a week of exposure to HF, the injured could see the bone of the thumb and it took a long time for recovery.

Though, I could not make out the injury from the normal appearing thumb, but the pain underwent is visible, when he narrated the incident to the audience.

Search from internet shows incidents, wherein, innocent persons just washed off the spillage with some water and continued their work, but were found dead in the sleep.

As per standard practice, in case of any chemical splash, remove the clothing and wash the affected organs for atleast 15 minutes and consult the doctor. Even after 15 minutes wash, only about 95% of the chemical is removed and thus care is very much required. One should not ignore the advice by experts.

Explosion in the plant leads to HF gas release

In an explosion in a chemical plant, HF gas leaked causing 5 deaths, injuries to 18 persons and hospitalization of more than 3500 persons. It is stated that the half life of HF is two years and requires monitoring of all affected persons for many years and also ground water contamination.


http://www.koreatimes.co.kr/www/news/opinon/2012/10/202_121828.html

Know about eye wash shower

An article in detail about eye wash shower location and care to be taken is available in the following link.

http://www.chemicalplantsafety.net/safety-equipment/what-you-need-to-know-about-eye-washer/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+ChemicalPlantSafety+%28Chemical+Plant+Safety+Resources%29

I learnt from this that the eye wash shower should be reachable in 10 seconds, to be located at same level of hazard area and dust covers should be provided to avoid contamination.

It is also stated that ANSI requires 30-90 psi pressure. It is my feeling that high pressure water should not be used as in the literature, hazards of high pressure water jets on eyes state damage to the eyes.

As per Indian Standard, the pressure to be maintained is 196 kpa i.e about 30 psi and 16 lpm flow rate for eye wash fountain and for emergency shower, it should be 110 lpm. As per this standard, it should be located within 15 m distance from chemical handling area.

The reason for minimum 15 minute cleaning is that even after this much cleaning, only about 95% chemical is washed off, which I read in internet written by an author from US about HF splash on the lab coat. I used to explain this to my audience in the training programmes about the necessity for washing atleast 15 minutes. Otherwise, human tendency is to wash till such irritation exists. However, the vapors from the chemical soaked cloth can continue to expose the persons and cause health effects later. And, HF will show delayed effects affecting lungs and exposed persons can die due to odema.

Man Choked on HF acid cloud at refinery - experience briefing

Giant Acid Cloud in Nevada Desert

Spread of acid fumes from broken bottles to three villages

A news item in Hindu news paper today is about leakage and impact of acid fumes on residents of three villages. The leakage and spread of fumes from possible broken bottles containing bromine (HBr?) caused health complications such as irritation in the eyes, trachea and stomach, coughing, nausea, skin allergy. Another report says about the quantity stored as 40 bottles of each 750 ml. And as per another report, it is stored in 2 and 5 lit bottles and liquid bromine from one broken bottle reacted with husk in the area. I am unable to guess what quantity of the chemical leaked that caused spread of thick fumes to three villages affecting the people. 
A report on the same incident mentions

Hydrofluoric acid hazard potential

There is an article on HF hazard potential which I could not believe about its extent. What I know is that, if HF comes in contact with skin, it can cause burns, nasal rupture if inhaled, punctures and penetrates through the bone. But, the article mentions about its distance of impact of 2 miles from the source when travels as a cloud.
HF is used a catalyst in refineries to make high octane gasoline, as mentioned in the article. The IDLH is 30 ppm and it was found at 2 miles distance when 1000 gal was released from tanker containing 5000 gal at a pressure and temperature as used in refineries. The HF travelled as vapour and mist and needed 40 parts of water for every part of HF to dilute it, though the officials doing the experiment thought that it will remain as a liquid and can be contained. The article also mentioned about use of an additive to make HF less dangerous by way reducing its ability to form vapour cloud.
Few years ago, I read an article in the internet, in which a college girl died because of HF. When she was doing experiment, few HF drops splashed on her lab coat. She washed it with water for sometime and continued her lab work. She was found dead by her neighbours, the next day. The reason mentioned is that the vapour from lab coat was inhaled by the girl and this lead to oedema.
In a book on Bhopal accident, I read that few years before, in the same plant a similar death occurred from phosgene splash on the body. Here, the lesson is that we should not be complacent and assume that by washing for a minutes, the chemical can be cleaned. Once some chemical splashes, we should takeout the clothing. This should be followed with water wash.
Normally, as a safety precaution, one should wash for at least 15 minutes once any chemical splashes/falls on the body. Even then, studies show that only about 95% of the chemical on the skin can be washed off. During my safety lectures, I tell my audience that during the beginning of every shift, atleast once, they should check for availability of water in emergency shower/eye wash fountain and allow the water to run for few minutes so that any dirt/rust collected can run off. Else, the damage from this dirty water may be more than that from the chemical splash.