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© Imperial College LondonPage 1 Foundation Training in Biological Safety.

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Presentation on theme: "© Imperial College LondonPage 1 Foundation Training in Biological Safety."— Presentation transcript:


2 © Imperial College LondonPage 1 Foundation Training in Biological Safety

3 © Imperial College LondonPage 2 Module 3 Working with gases and cryogenics in the biological laboratory

4 © Imperial College LondonPage 3 Common gases - physical properties and hazards CARBON DIOXIDE (GASEOUS) Description: Colourless, odourless gas. Pungent odour at high concs. Relative density (Air = 1): 1.52 Flammable? No Workplace Exposure Limits: 1.5% (short term), 0.5% (long term) Hazards: Intoxicating at high concentrations (5%+)

5 © Imperial College LondonPage 4 Common gases - physical properties and hazards CARBON DIOXIDE (SOLID) Description: Translucent white solid Pellets or flakes. Relative density (Air = 1): 1.52 Flammable? No Workplace Exposure Limits: 1.5% (short term), 0.5% (long term) Hazards: Cold burns / frostbite Sublimes to form gaseous CO2 – asphyxiation risk

6 © Imperial College LondonPage 5 Common gases - physical properties and hazards Don’t play games with dry ice!

7 © Imperial College LondonPage 6 Common gases - physical properties and hazards NITROGEN (GASEOUS) Description: Colourless, odourless gas. Present in air ~ 78% Relative density (Air = 1): 0.97 Flammable? No Workplace Exposure Limits: None Hazards: Asphyxiation by reduction in O2 content of air

8 © Imperial College LondonPage 7 Common gases - physical properties and hazards NITROGEN (LIQUID) Description: Colourless, odourless liquid (-196 o C) Relative density (Air = 1): Cold gas / vapour heavier than air Expansion factor of x700 Flammable? No Workplace Exposure Limits: None Hazards:  Asphyxiation – evolved gas will displace air  Cryogenic burns  Frostbite and hypothermia in certain circumstances

9 © Imperial College LondonPage 8 Common gases - physical properties and hazards HYDROGEN Description: Colourless, odourless gas Relative density (Air = 1): 0.07 Flammable? Extremely Workplace Exposure Limits: None Hazards: Fire and explosion

10 © Imperial College LondonPage 9 Hazard information MSDS and Hazard Labels

11 © Imperial College LondonPage 10 Foreseeable risks  Regulator failure  Failure of pipework or tubing connecting cylinder to other equipment  Overpressurisation  Damage caused by impact e.g. falling cylinder or vessel  Damage caused by fire Uncontrolled release of gas due to:

12 © Imperial College LondonPage 11 The control hierarchy Prevent or minimise the risk of release at source 1 Disperse the gas before it reaches a critical level 2 Warning systems should the gas reach a critical level 3

13 © Imperial College LondonPage 12 Control measures  Ensure regulators and associated pipework are designed and fitted to recognised standards. Be guided by the gas supplier  Ensure that any flexible tubing is securely fixed  Consider fitting safety devices such as excess flow valves

14 © Imperial College LondonPage 13 Control measures  Ensure that regulators, pressure vessels etc. are subject to maintenance and inspection regimes  Ensure cylinders are secure and away from sources of heat  Training – ensure that users are familiar with the equipment and the properties of the substances they are handling

15 © Imperial College LondonPage 14 Control measures  Wear appropriate Personal Protective Equipment (PPE)  Ventilation – ensure that it is adequate  Ensure the physical environment is suitable for liquid nitrogen dispensing e.g. floor surfaces, adequate space for manouevre  Consider fixed point gas detection monitors / alarms  Ensure emergency procedures have been considered

16 © Imperial College LondonPage 15 Some Do’s……… Always:  Store bulk quantities of cylinders upright in purpose-designed storage areas  Segregate full and empty cylinders  Segregate flammable and non-flammable gases  Keep cylinder valves clean  Ensure the correct regulators are fitted  Ensure the regulator is designed to take the cylinder pressure  Observe for faults and leaks at each time of use

17 © Imperial College LondonPage 16 Never:  Tamper with cylinders in any way  Dispose of cylinders in any way other than returning them to the suppliers  Oil or grease cylinder fittings  Use PTFE tape to achieve a seal  Use non-standard cylinder keys  ‘Snift’ hydrogen or toxic gases ……… and some Don’ts

18 © Imperial College LondonPage 17 Manual handling cylinders and vessels  Make use of the BOC ‘point-to-point’ service on sites where this is in force  Plan your route in advance  Avoid moving cylinders through populated work areas  Report problems with paths and roadways to Estates  Be aware of your physical capabilities – some jobs need to be carried out by two people  Use purpose designed trolleys  Never roll a cylinder  Don’t attempt to catch a cylinder if it falls  Never transport a cylinder off site without consulting BOC / College Safety Department  Never travel in a lift with liquid nitrogen vessels

19 © Imperial College LondonPage 18 Removing specimens from liquid nitrogen vessels  Store the samples in the vapour phase  Place the vial into secondary containment immediately after removal  Wear appropriate PPE e.g. full face visor There is a risk that vials may explode as liquid nitrogen warms and converts from liquid form to gaseous PRECAUTIONS:

20 © Imperial College LondonPage 19 Carrying out and recording the risk assessment STEP 1: Identify the hazards STEP 2: Identify who may be at risk STEP 3: Establish control measures STEP 4: Record the assessment STEP 5: Review the assessment

21 © Imperial College LondonPage 20 Accidents do happen……  CO2 cylinder safety valve vented  Cylinders left unsupported  Cylinders obstructing fire escape route  Leaks from reducing valve  Cylinders dropped / fell in transit  Liquid nitrogen vessel toppled in transit  Burst silicone tubing carrying gas  Connector tubing became detached  Failure of trolley wheels on liquid nitrogen vessel  Structural failure in neck of liquid nitrogen vessel

22 © Imperial College LondonPage 21 Sources of further information Safety Department website: cryo Internal External BOC: HSE: British Compressed Gases Association (BCGA):

23 © Imperial College LondonPage 22 Workshop Exercise 1 SCENARIO: You are working at the bench in a Containment Level 2 laboratory. There is one other person in the laboratory with you. You are alarmed by a sudden and very loud sound like a gas release. You assume that it is coming from the carbon dioxide cylinder in the corner of the laboratory. WHAT DO YOU DO NEXT?

24 © Imperial College LondonPage 23 MODEL ANSWER 1.Quickly make safe what you are doing then leave the room and advise the other person to do the same. Try not to panic. 2.Close the door and secure the room if possible. If the room has to be left unattended, ensure a warning sign is posted. 3.Report the incident to your Group Safety Adviser / DSO. 4.Do not re-enter the room unless you know it is safe to do so. Both the Safety Department and the BOC staff based within the College have access to basic detection equipment that can be used to determine the level of CO2 within the room before entry. 5.If gas detection equipment is not available, leave the room secured with warning signs in place until the cylinder has fully vented. Do not investigate the matter any further at this stage. It will normally need to be left until the following day to ensure that it has emptied and the atmosphere cleared. The atmosphere will clear more quickly if the lab is mechanically ventilated. A calculation can be carried out to give a rough estimate of what level the gas may reach and how quickly it may clear. 6. The following morning, open the lab door and leave open for a few minutes before entering. Check the cylinder is no longer hissing. There should be at least two people present. 7.Ensure that BOC are aware of the problem – they will need to reclaim the cylinder for investigation. 8.Complete a dangerous occurrence report in accordance with established College procedures.

25 © Imperial College LondonPage 24 Workshop Exercise 2 SCENARIO: You need to collect a full liquid nitrogen vessel from the cage at the rear of the Biochemistry Building and return it to your laboratory on the 4 th floor. Vessel type: 240L transportable pressurised vessel with integral trolley & tow bar. Weight: 329Kg when full. Goods Lift: Key controllable. No size restrictions. WRITE A SIMPLE STANDARD OPERATING PROCEDURE (SOP) FOR THE TASK

26 © Imperial College LondonPage 25 MODEL ANSWER 1.Obtain the key to the storage cage from XXXXXXXXXX (local variations). 2.Ensure that the goods lift is operational. 3.Obtain the assistance of a second member of staff. 4.Ensure that correct PPE is worn by both staff (specify). 5.Proceed to storage cage, open the door, remove vessel and lock door again. 6.Wheel the vessel to the back door of the goods lift (both members of staff). 7.Load the vessel into the lift. First member of staff to proceed to destination floor via alternative means. 8.Second member of staff selects the key control function and sends the vessel unaccomapanied to the destination floor to be met by the first person. Second member of staff proceeds to the destination floor by alternative means. 9.Remove vessel from lift and set the control back to ‘manual’. 10.Wheel vessel to laboratory and return cage key to XXXXXXXXXXX.

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