THE UNIVERSITY OF NEWCASTLE - DISCIPLINE OF MEDICAL BIOCHEMISTRY

Transcription

1 THE UNIVERSITY OF NEWCASTLE - DISCIPLINE OF MEDICAL BIOCHEMISTRY Page: 1 of 9 1. Risk Assessment: This Risk Assessment is to be used as a general guide and as such, cannot accommodate all the varying factors that may be encountered when using this equipment. Therefore, personnel are requested to conduct their own Risk Assessment before using this equipment to include any extra hazards introduced by the task performed. TASK PERFORMED Use of Liquid Nitrogen and Liquid Nitrogen Tanks 1. Cold Temperature Burns 2. Asphyxiation 3. Explosion HAZARDS RISK ASSESSMENT 1. The risk of burns from liquid nitrogen is present whenever the substance or associated materials are handled. Due to the temperature of Liquid Nitrogen, -196 C, any burns sustained cause a similar injury to high temperature burns. Burns may even occur after brief contact. Frostbite (local freezing of tissue) may result from actual contact with the liquid or by exposure to the vapour only. Eyes are especially susceptible to damage due to their high water content. Inhalation of the vapour may cause breathing discomfort and prolonged inhalation may cause permanent damage. 2. The risk of asphyxiation is present while ever liquid nitrogen is being handled, and the risk increases as the ventilation and room size decreases. Due to the rapid expansion rate of liquid nitrogen (1 volume of liquid creates 700 volumes of gas) asphyxiation may occur due to oxygen displacement. If the oxygen concentration is dangerously low, asphyxiation may occur and personnel may become unconscious without sensing any of the warning signs such as dizziness. Liquid nitrogen will cause water vapour to condense, forming a mist. In the event of a large spill, such a mist may create orientation problems. Inhalation of the vapour may cause breathing discomfort and prolonged inhalation may cause permanent NAME (signed) DATE WRITTEN BY CHECKED BY Distributed To: GEP Master File / GEP Lab File

2 Page: 2 of 9 damage. 3. Due to the rapid expansion rate of liquid nitrogen (1 volume of liquid creates 700 volumes of gas) it always presents an explosion risk, even when stored. There is also a risk of splashing due to the rapid boiling that occurs when liquid nitrogen is transferred to vessels of a higher temperature, or when items of a higher temperature are inserted into it. Caution must be taken when handling/thawing tubes containing biohazardous materials, due to the risk of explosion. Liquid Nitrogen may also condense oxygen from the air. If the oxygen content becomes significant, the explosion risk increases and the liquid nitrogen must be handled using the same precautions used when handling liquid oxygen. Oxygen contamination is indicated by a blue tint in the liquid nitrogen. RISK CONTROL 1. Ensure that all operators are trained before handling liquid nitrogen. Always wear a fullface mask, cryogloves, lab coat and enclosed leather shoes when handling liquid nitrogen. The liquid nitrogen tank must not be stored in a confined area, nor should liquid nitrogen be used in a confined area. Stand as far away as possible from the tank when transferring liquid nitrogen and perform all operations (such as pouring) slowly, to avoid violent boiling. Objects such as tongs may become brittle when immersed in liquid nitrogen and are easily broken. See Handling Precautions in section 4 for liquid nitrogen burn First Aid Procedures. 2. The liquid nitrogen tank must not be stored in a confined area, nor should liquid nitrogen be used in a confined area. Stand as far away as possible from the tank when transferring liquid nitrogen and perform all operations (such as pouring slowly), to avoid violent boiling. See Handling Precautions in section 4 for liquid nitrogen burn First Aid Procedures. 3. Use only specially designed containers for storing and transporting liquid nitrogen. Check the storage containers regularly and remove any ice buildups in and around the vents. Only use the stopper/lid that is provided with the cylinder - these are designed to prevent a buildup of pressure. Use only specially designed Cryotubes for freezing samples. Inspect the liquid nitrogen regularly for the appearance of a blue tint. If present, remove all containers and allow the liquid nitrogen to evaporate in a secure, well-ventilated area. Do not use an electric pump to remove the liquid nitrogen, nor expose the tank to any ignition sources (cigarettes, electrical equipment) or materials such as organic substances, oil, grease, wood, cloth or dirt, all of which may initiate a violent explosion. See the CCH Laboratory Safety Manual for more information.

3 Page: 3 of 9 2. Calibration: N/A 3. Monitoring: 3.1 Frequency: Weekly 3.2 Method: Monitoring Liquid Nitrogen Levels Before attempting this procedure, see the Handling Precautions in section 4 for liquid nitrogen burn First Aid Procedures. While wearing a lab coat, enclosed leather shoes, a full-face mask and cryogloves, remove the lid of the liquid nitrogen tank. Slowly lower a liquid nitrogen dipstick into the tank until it touches the bottom, then remove the stick. Replace the tank lid. Blow warm breath onto the stick - the condensing water vapour will create a visible frost line on the stick, indicating the level of the liquid nitrogen. NB Always use a proper dipstick. Never use a hollow tube to measure the liquid nitrogen level. When a warm tube is inserted liquid nitrogen will spout from the top of the tube due to rapid expansion. Never use wooden rods as dipsticks Different materials may be stored at different temperatures within the various liquid nitrogen phases. Materials that are stored at the liquid phase must be constantly covered by liquid nitrogen. Those that only require gas-phase temperature storage require a lower liquid nitrogen level. See Attachment 11.1 for more information and a diagram (Fig. 6). For instruction on filling a tank, see Section 4, General Operation. 3.3 Records If a record of the gas phase temperatures is required, use the Temperature Monitoring Record Sheet, Illustration Once the Temperature Monitoring Record Sheet is complete, file it in the appropriate section of the Equipment Records Folder. 4. HANDLING PRECAUTIONS - EMERGENCY PROCEDURES 4.1 LIQUID NITROGEN SPILL - The best way to deal with a spill of liquid nitrogen is to provide the area with maximum ventilation and allow the spill to

4 Page: 4 of 9 evaporate. However, be aware of the probability of rapid oxygen displacement which may lead to asphyxiation, and close the area off accordingly. In the event of a liquid nitrogen spill: 1. Assess the asphyxiation risks and order an evacuation if necessary 2. Administer first aid where required 3. Ventilate the area well. 4.2 FIRST AID - COLD CONTACT BURNS 1. Seek medical advice and/or a first aid officer immediately. If unavailable, place the casualty in a warm place, and allow the injured area to warm gradually. Further damage may occur if the area warms too quickly. DO NOT expose the injured area to excessive heat or cold sources. 2. Gently cover the injured area with a clean non-adherent dressing. 3. To relieve pain, immerse the area in water at a temperature of C. 4. Give the casualty a hot drink but do not administer alcohol. 5. Fill out or witness an accident form. 4.3 ASPHYXIATION 1. The rescuer of an asphyxiated person should be careful not to take excessive risks and become another casualty. 2. Take the casualty to a well-ventilated area 3. Have someone else contact a first aid officer immediately. 4. Apply artificial respiration if breathing has stopped. 5. Seek professional medical attention 6. Fill out or witness an accident form. NB This information is included in Attachment Liquid Nitrogen Emergency and First Aid Procedures, which can be displayed in the laboratory near the Liquid Nitrogen tanks as a ready reference. 5. General Operation: 5.1 Only attempt the following procedures while wearing a lab coat, enclosed leather shoes, a full-face mask and cryogloves.

5 Page: 5 of WHEN FILLING A LIQUID NITROGEN TANK that is completely empty, be sure to pour the nitrogen in very slowly, as rapid boiling will occur due to the bottom of the tank being at room temperature. 5.3 TO TOP UP THE TANK, use a proper liquid nitrogen pump or pour the nitrogen straight from the transport vessel into the tank, taking care not to spill it or pour too quickly. NB Do not attempt to lift any nitrogen tanks that are too heavy, always seek assistance. Ensure that all staff who are to handle liquid nitrogen have received manual handling training. 5.4 Refer to Section 3 - Monitoring, for instruction on measuring the liquid nitrogen levels. 5.5 Ensure that the tank lid is replaced properly at all times. If not, the liquid nitrogen may evaporate at a greater than usual rate. 5.6 It is preferable to freeze cryovials containing cells at -80 C first, before storing them in liquid nitrogen. This two-step process will help to prevent cell-damage and loss of viability caused by rapid temperature adjustment. 5.7 TO STORE NEW ITEMS/RETRIEVE ITEMS IN LIQUID NITROGEN, remove the lid of the tank and place it upside down on a flat surface. Extract the container required by lifting it off the lip of the tank and moving it to the centre before lifting it up. Only lift the container to the height of the lip and no further. Lift out and hold the required cane with one hand while slowly returning the container to its storage position with the other. Leave the cane in the mouth of the tank while handling. Slide off the cane cover (if it has one) then use forceps to insert the vial into the desired position. Replace the cane cover, extract the container from the tank and replace the cane into the container. Slowly lower the container back into the liquid nitrogen tank and ensure that the lid is replaced properly.

6 Page: 6 of If a Liquid Nitrogen Log Book is in use ensure that all sample addition/removal details are recorded. 5.9 For further information on Preparation of Cells, Rate of Cooling etc, Refer to the NUNC Cryopreservation Manual (in the Medical Biochemistry Reference Folder, LS3-26). 6. Cleaning: 6.1 Frequency: When required 6.2 Method Cleaning should only be required if there has been a spill of tube contents into the liquid nitrogen, or if other foreign material is present While wearing a lab coat, cryogloves, enclosed leather shoes and a fullface mask, move all contents of the liquid nitrogen tank to another liquid nitrogen tank. Leave the tank to be cleaned in a secure, well-ventilated area and allow the nitrogen to evaporate completely Once empty tip the tank upside down and shake to free any tubes or other items that may have fallen into the tank. If the tank requires further cleaning, rinse it out with water. Leave to dry completely For instructions on filling an empty liquid nitrogen tank, see Records Record all cleaning details on the Maintenance Record Sheet (Illustration 10.2). Once the Maintenance Record Sheet is complete, file it in the appropriate section of the Equipment Records Folder. 7. Maintenance: See Monitoring 8. Instruction Manual: 8.1 See the Equipment Register for availability 9. Repairs: 9.1 Check the Equipment Register for Service Company and warranty details

7 Page: 7 of Contact the University Workshop for advice and repairs 10. Illustrations: 10.1 Temperature Monitoring Record Sheet 10.2 Maintenance Record Sheet 11. Attachments: 11.1 Storage 11.2 Liquid Nitrogen Emergency and First Aid Procedures 12. Change History: 12.1 Issue Number: 1st Issue Date Issued: 12.2 Issue Number: Date Issued: Reason for Change:

8 Page: 8 of 9 ILLUSTRATION 10.1 TEMPERATURE MONITORING RECORD SHEET EQUIPMENT REGISTER # MONTH: LOCATION: YEAR: Date Temp. Initials Date Temp. Initials

9 Page: 9 of 9 ILLUSTRATION 10.2 MAINTENANCE RECORD SHEET EQUIPMENT REGISTER # DATE MAINTENANCE SIGNED