nitrogen3 1 safety doc

7/27/2019 Nitrogen3 1 Safety Doc

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LIQUID NITROGENSAFETY DOCUMENTS


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LIQUID NITROGEN: GOLDEN RULESKnow the Emergency Procedure!!

1. LN2 storage tanks are located in room C.272. Always wear your safety glasses.3. Always wear your leather gloves.4. Always use the rigid syphon and gas phase separator.5. Always use vessels designed for LN2.6. Never use plastic, glass or rubber with LN2 .7. Ensure receiving vessel is secure.8. Open valves slowly and be aware of gas noise from gas phaseseparator or LN2 pressure relief device.

9. Avoid splashing and use minimum quantity required.


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The Department..,j,. University Of * RiskAssessment For-mf Physics &Sheffield. Astronomy.

PERSONS AT RISK: ( XElllP!Oyees (x )Students () Public (x)Visitors (x ) Others Reference No;Risk : (H ) High (M) Medium (L) Low (0) No risk Environment: Laboratorvand storage areas Q ' ~ _ Q . f . ! L q j ( t m n 2 g ~ ! ! L r i l i ! ? 2 . r . . e . e ~ . . i l ! 1 i L ._- ~ ---- .- - - --.----- - --- - -.--.----- -- --.- ----- .-..- -- .--- ~ i ~ i 1 sto rage areas

SIGNIFICANT HAZARD POTENTIAL CONSEQUENCES OF RATING EXIS TING CONTROL/PROPOSED CONTROL MEASURES RATINGHAZA.RDLiquid between 8L-1 8L Cold burns Ifrostbite M i.Ensure workplace and work area is well ventilatedz.Use minimum quantities necessary3.Use PPE minimumleather gloves and eveprotection L4.Ensure that all workers are trained andinstructed in its useI) . Useonly eouiurnent and containers designed for use with LN26.Ca1culate maximum quantiti es suitable for thework area

Liquid greater than 18L Asphyxiation due to rapid conversion of H i.Contr ols as listed above }liquid to gas 2. Installation of Oxygen Deficiencysensing where oxygen }concentrations would be lower than 18% inthe event of totalconversionof liquid to gas Lowlevel sensing approx D.7m fromfloor levelCold burns /frostbite 3.0>"j'gen sensor-S monthly calibration & 12 monthly } Lreulacernent4. EmerzencvProcedure inthe event of a lowoxygen level alarm }

__ . Q ! ! l , ! ! ! ~ ! 1 . ~ ~ ._. ._ _. . . . _ ._ ____ __ _ _ . . -' Overall Risk : L . . i l ~ ~ E ~ J ! l . . Q . : ~ ~ __ . . ._... ._ . . _. __

_ < ! ~ ! ! ! Q ! ! ~ ! ~ ~ ~ : ! _ ~ k s ~ . ! ~ . ~ . ._. ._.__ . . . . ._ ._. . .__. . ._ ._. ..__.._ ._ . .. .1. Read the additional safetyinformation withinthe cryogenics section ofthe LaboratorySafety folder. (General & Safe Working Practices and Emergency__ ~ ~ ! ! i ! ! ~ ~ Q . @ Q ~ ! ~ n l . ~ ~ . : . . ~ ! ! . . ~ ~ ! ! . . Q . . < l . ! ' . ! . . Q ! n g . . i l ! ! .c ! B ; f . t : i ~ ...___. . .. .__. ._. _

_ . . Q y . ~ . . I : V i c k ~ _ ~ L __. . ..__.. ..__. ._ _ . . . .. ...._._ ..__. ._..__ _._. ..._.__. ._ . .__ .. . .__ ..~ ~ ~ ~ . < t . . . ! 2 i : . . . ~ : ~ Q ~ ~ ! ! ! i l l ~ L ~ ! ! : - A . ~ ! ! ! ~ m . g . - - - - s " f ; ; ; ; , - - a t e : - - - -.---..-.-- - -.-.--. --- -


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EmergencxProcedure forLiquid Nitrogen

In the Research LaboratoryNo asphyxiation hazard as maximum quantities should never be exceeded.In case of total spillage, open windows and main door and allow to disperse.

In the Liquid Nitrogen Store (C 27)A Never enter the room if the Oxygen deficiency alarm is going off


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Recommended procedure for transportation ofCryogenicLiquids using the Goods liftLiquid NitrogenOpen top dewars - typically the 4L Polystyrene containers should NOTbe transported in the lift. In the event of spillage the liquid expansionvolume would cause an asphyxiation environment. All such movementsshould be made using the staircase and no more than two at a time.Low Pressure sealed dewars (l60L volume) - rarely, if ever shouldthese vessels need to be transported in the lift. If required to do so, it isimportant that the gas over pressure is reduced to 50% of the relief valvepressure in a well ventilated area. This would be typically 1Opsi/ 0.7 barg.In the event of breakdown , use the emergency alann for assistance, donot panic since the relief valve setting will take more than 12 hours to bereached. It is recommended that such a procedure is undertaken by amember of the liquefier staff.Liquid HeliumlOOL sealed dewars - commonly transported between C&D floors. Onlyvessels that have been previously connected to the helium recovery


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Department of Physics and AstronomySafe Working Procedure

This form should be completed for each procedure that may be undertaken in the designated area, which has ahazard or potential hazard associated with it.Each procedure an undergraduate, postgraduate, research associate, staff member, technician or secretary isexpected to perform, must be adequately explained, (with the aid of this form) at the time of their inductioninto the working area , by a suitably qualified person.Date: October 2005Location : Experimental Physics & Astronomy Research LaboratoriesName of supervi sorGeneral guide: specific procedure to be determined by individualsDetails of the procedure : LIQUID NITROGEN USELocation for LN 2 store is C.271.00 not enter the room if the Oxygen Deficiency alarm is sounding or the light is flashing.lmmediately reportthis to the liquefier staff or senior staff member2. Never take storage containers(240L Wessington) to a research laboratory unless it has a low level sensor forOxygen Deficiency monitoring .(See guide for transport ation if moved from C.27)3.Should the alarm sound , close the storage vesse l valve and exit the room . Follow the Emergency Procedure inthis eventImportant information prior to using LN2I.Read and understand the guidance notes contained within the cryogenics section of the Laboratory Safetyfolder situated in each research laboratory2.Calculate the maximum quantities permitted in the laboratory/work area, but use the minimum that isnecessary ( See calculation information)3. Receiv e appropriate PPE and a practical demonstration from a competent colleague4. Sign the declaration as a registered and trained user(Pl ease see C.Vickers,C.10)5. Only use 4L capacity polystyren e containers and carry no more than 2 at anytime .


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To calculate the maximum permitted asphyxiant that can bestored in a Laboratory so as to preserve a life sustainingatmosphere in the case of spillage or accidental venting.

Assume that the asphyxiant is fully mixed with the air in the room.The normal concentration of oxygen is 20.9%Oxygen concentrations below 18% are considered hazardous.The volume of asphyxiant is therefore given by,

v ==v _0.18VR m'A R 0.209

where VR is the volume of the room in rrr', or

Example: what is the largest volume of liquid nitrogen that can be safely storedin Cll Laboratory, to avoid an oxygen depleted atmosphere?Data Volume ofCll Laboratory = 127 m3


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ROOM OXYGEN CONCENTRATIONS -IN FULLY MIXED ATMOSPHERE - RESULTING FROM LEAK I SPILLAGEROOM VOLUMES (in m3 )

NITROGEN VOLUME 50 100 150 200 250 300 400 500 750 1000 1250Cylinder (size mm) GAS (m3) OXYGEN CONCENTRATION140x940 (230 bar) 2.1 X 20.1% 20.5% 20.6% 20.7% 20.8% 20.8% 20.8% 20.9% 20.9% 20.9% 20.9%230x1460 (230 bar) 9.78 W 16.8% 18.9% 19.5% 19.9% 20.1% 20.3% 20.4% 20.5% 20.7% 20.7% 20.8%230x1640 (230 bar) 10.78 Z 16.4% 18.7% 19.4% 19.8% 20.0% 20.2% 20.4% 20.5% 20.6% 20.7% 20.8%CARBON DIOXIDE VOLUMECylinder (size mm) GAS (m3) OXYGEN CONCENTRATION140X940 (50 bar) 3.3 19.6% 20.3% 20.5% 20.6% 20.7% 20.7% 20.8% 20.8% 20.9% 20.9% 20.9%203x870 (50bar) 7.3 17.9% 19.4% 19.9% 20.2% 20.3% 20.4% 20.6% 20.6% 20.7% 20.8% 20.8%230x1496 (50bar) 18 13.4% 17.2% 18.4% 19.1% 19.4% 19.7% 20.0% 20.2% 20.4% 206.0% 20.6%ARGON VOLUMECylinder (size mm) GAS (m3) OXYGEN CONCENTRATION230x1460 (230bar) 11.01 16.3% 18.6% 19.4% 19.8% 20.0% 20.2% 20.4% 20.5% 20.6% 20.7% 20.8%NITROGEN VOLUMELIQUID (Ii tres ) GAS (m3) OXYGEN CONCENTRATION10 6.83 18.1% 19.5% 20.0% 20.2% 20.4% 20.5% 20.6% 20.7% 20.7% 20.8% 20.8%25 17.1 13.8% 17.4% 18.6% 19.2% 19.5% 19.8% 20.1% 20.2% 20.5% 20.6% 20.7%50 34 .1 6.6% 13.8% 16.1% 17.3% 18.1% 18.6% 19.1% 19.5% 19.9% 20.2% 20.4%100 68.2 0.0% 6.6% 11.4% 13.8% 15.2% 16.2% 17.3% 18.1% 19.0% 19.2% 19.8%150 102.3 0.0% 0.0% 6.6% 10.2% 12.4% 13.8% 15.6% 16.7% 18.1% 18.8% 19.2%200 136.4 0.0% 0.0% 1.9% 6.6% 9.5% 11.4% 13.8% 15.2% 17.1% 18.1% 18.7%250 170.5 0.0% 0.0% 0.0% 3.1% 6.6% 9.0% 12.2% 13.8% 16.2% 17.3% 18.1%300 204.6 0.0% 0.0% 0.0% 0.0% 3.8% 6.6% 10.2% 12.4% 15.2% 16.6% 17.5%400 272.8 0.0% 0.0% 0.0% 0.0% 0.0% 1.9% 6.6% 9.5% 13.3% 15.2% 16.4%500 341 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 3.1% 6.6% 11.4% 13.8% 15.2%600 409.2 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 3.8% 9.5% 12.4% 14.1%Oxygen concentrations below 18% must be considered hazardousThe calculations above will be valid where the gas is fully mixed with the air in the room.At the point of the leak I spill - the concentration of oxygen will be significantly lower than indicated above.If 2 cylinders are connected via a changeover valve then the maximum volume of gas which could leak doubles, and the resulting Oxygen concentration

can be calculated by halving the room volume and reading off the Oxygen concentration for the smaller sized room.

nitrogen3 1 safety doc

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