1

CRYOGEN SAFETYSafe Use of Liquid Nitrogen (LN2)

By Reece Stockport

Departmental Cryogenic Safety Advisor

2

TRAINING OUTLINE

HazardsPersonal Protective EquipmentExposureSafety Procedures

General UseContainer Filling Procedure

Questions

3

HAZARDS

4

HAZARDS

Liquid Nitrogen (LN2) can cause severe frostbite or eye damage upon contact. Liquid nitrogen is liquefied by cooling nitrogen

gas down to (or below) its boiling point [-320ºF (-196ºC)].

Substances may become brittle upon contact with LN2 and shatter.

Expands by a factor of 700 upon vaporization

5

HAZARDS (2)

May cause explosion of a sealed container

Can Cause Asphyxiation

LN2 should be used and stored in well ventilated areas!

6

PERSONAL PROTECTIVE EQUIPMENT

7

PPE- EYES

ANSI approved safety goggles must be worn when handling LN2. When filling your Dewar from the larger vessel a full face shield must be worn. Safety glasses do not provide adequate

protection from potential splash hazard of large quantities.

8

PPE- HANDS

Cryogenic gloves are required when Dispensing from LN2 container. At any point whilst transporting and handling LN2

Limited resistance to direct exposure to liquid nitrogen (splash

resistant)

9

PPE- BODY & FEET

When handling LN2 Fully enclosed shoes are required (no open-toe or canvas

shoes, sandals, or clogs) Long pants and long sleeve tops or a lab coat must be

worn (no shorts or short-sleeved shirts)

10

HOW YOU SHOULD LOOK!

11

EXPOSURE

12

EXPOSURE- SKIN CONTACT

Skin contact can cause severe cold burns and frostbite.

Flesh freezes very rapidly, flesh may be torn attempting to be withdrawn from object

13

WHAT SHOULD I DO IF IT OCCURS? If frostbite or freezing occurs, the following steps

should be taken:

Call a first aider! Who will;

1. Flush area thoroughly with tepid water Do not apply direct heat Do not rub affected area

2. Protect area with bulky, dry, sterile dressings3. Seek medical attention4. Notify supervisor

14

EXPOSURE- EYE CONTACT

Eye exposure can cause permanent irreversible damage

Delicate eye tissue can be damaged by exposure to the cold gas alone

15

WHAT SHOULD I DO IF IT OCCURS? If liquid is splashed into eyes, do the following:

Call a first aider! Who will;

1. Flush with water for 15 minutes2. Seek medical attention if needed3. Notify supervisor

16

EXPOSURE- ASPHYXIATION With asphyxiation, unconsciousness may happen

without warning If the person becomes dizzy, move them to a well-

ventilated area and seek a first aider Notify supervisor

Oxygen content (vol %)

Effects and symptoms (at atmospheric pressure)

11-16 Reduction of your physical and intellectual performance without the person being aware.

8-11 Possibility of fainting without prior warning.

6-8 Fainting within a few minutes, resuscitation possible if carried out immediately.

0-6 Fainting almost immediate. Fatality!

17

SAFETY PROCEDURES

18

GENERAL SAFE USE

All Activity must be Risk Assessed by a competent person!

Have a procedure when working with LN2;

procedure should include: Use only in well ventilated and low traffic areas Wear appropriate PPE LN2 should only be handled in approved containers

Avoid breathing LN2 vapors Carry containers away from body and face Do not leave open containers unattended Leave to ventilate in a corner on completion (do

not throw on floor or pour down sink)

19

FILLING CONTAINERS

Double check your small Dewar has no cracks or any problems

Check the pressure relief valve is pointing away from people

Wear the appropriate PPE Take care when transporting your Dewar (DO

NOT OVER FILL)

I will now give a demonstration of the filling procedure.

20

QUESTIONS?