There are many safety errors operators can make when decanting liquid nitrogen. Here are the 6 most common errors that we see:
1. Not following an approved standard operating procedure
A standard operating procedure (sometimes called a method statement or a safe system of work) is a set of procedures according to which work must be carried out. Operators should be involved in the process of creating the safe system of work and they should set out in detail, the correct method for carrying out an activity such as decanting liquid nitrogen.
This can then be documented and used as part of the training procedure for staff undertaking this activity. Without a set method for carrying out a task safely and a recognised procedure in place to deal with non-routine processes, the threat of mistakes being made is high.
2. Decanting in a confined space
We frequently find operators decanting liquid in poorly ventilated areas. Liquid nitrogen is extremely cold and when it ‘hits the atmosphere’ and warms up it develops a large volume of nitrogen gas. This gas is colourless and odourless and does not support life and if released into poorly ventilated areas it can quickly produce an oxygen depleted atmosphere.
Remember – we need oxygen to live and breathe!
3. Wearing inappropriate PPE
When undertaking site visits, we find operators using leather welding gauntlets to decant liquid nitrogen rather than the correct, insulated gloves, manufactured to the relevant standard.
Operators wear shoes with lace holes which will allow liquid to soak socks as well as incorrect facial protection.
4. Decanting at too high a pressure
A common error is to decant the liquid at too high a pressure. Many operators are unaware of the role of the pressure gauge on a liquid nitrogen vessel, they don’t know how to reduce the head pressure or know the optimum pressure to smoothly and safely transfer the cryogenic liquid.
5. Not purging the supply hose
An essential element in the decanting process is to allow a flow of cold gas to purge the hose of any impurities prior to the transfer of the liquid.
Allowing cold gas to travel through the hose also begins to cool the hose and aids in the safe decanting of the liquid.
6. Using an inappropriate working vessel/flask
The vessel that the liquid is being transferred into must be suitable and capable of holding the cold cryogenic liquid.
During our extensive time delivering safety workshops we have discovered operators using many different types of receptacles to hold the cold liquid…from wheelbarrows through to galvanised dustbins!
Summary
If you recognise any of these liquid nitrogen decanting errors, then please contact our professional staff on 01270 758890 or email us at admin@gassafeconsultants.co.uk to discuss your operation, and we’ll help you to transfer your liquid nitrogen in a safe, controlled manner.
Our comprehensive workshop handouts include generic, safe decanting procedures, which you can use to assist you in writing your own detailed safe systems of work.
