Standard Operating Procedure for Safe Handling of Liquid Nitrogen

7/31/2019 Standard Operating Procedure for Safe Handling of Liquid Nitrogen

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Department of BiochemistryYong Loo Lin School of Medicine, NUS

Doc. No: SOP-BCH-WVS-007

Standard Operating Procedure

Title: Safe Handling of Liquid Nitrogen

Version No:Issue date:

0018 Nov 2010

Page: 1 of 3

1. OBJECTIVE

The objective of this SOP is to provide guidance on the safe handling of liquid nitrogen.

2. SCOPE

This SOP is applicable to all labs in the Department of Biochemistry, NUS.

3. RESPONSIBILITY

3.1 Principal InvestigatorsThe PI has the primary responsibility for the implementation of this SOP in their workarea. This involves:

(a) Preparation, proper storage, transfer and use of liquid nitrogen.(b) Providing appropriate PPE to employees and students where applicable.(c) Training of employees/users.

3.2 UsersUsers of cryogenic liquids must:

(a) Adhere to safe handling procedures(b) Wear appropriate PPE when handling cryogenic liquids

(c) Attend required training sessions.4. PROCEDURES

4.1 Personal Protective Equipment (PPE)(a) A face shield, cryogloves and a lab coat must be worn whenever you are

removing or keeping samples in a liquid nitrogen Dewar.

(b) Tuck the sleeves of your lab coat into the cryoglove so that your arm is fullycovered.

(c) Trousers should be worn over shoes/boot tops to prevent shoes from filling

with liquid nitrogen in the event of a spillage. In general, before handling aliquid nitrogen Dewar, ensure that your bare skin will not come into contactwith the liquid.

(d) Watches, rings, and other jewelry should NOT be worn.

(e) If liquid nitrogen spills onto your cryogloves or shoes, remove themIMMEDIATELY. The low temperatures numb everything so fast that no pain isfelt while frostbite is incurred. The damage, which can be equivalent to secondor third degree burns, is only noticed after gloves or shoes are removed, andrequires treatment in a hospital.

(f) Unprotected body parts should not come in contact with vessels or pipes thatcontain cryogenic liquids because extremely cold material may bond firmly tothe skin and tear flesh if separation is attempted.

Mr. Wong Veen SennDr. Lim Cheh Peng

Dr. Takao InoueA/P Caroline Lee

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Prepared by Approved By Review Date


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0018 Nov 2010

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4.2 Storage(a) Cryogenic liquids should be handled and stored in containers that are

designed for the pressure and temperature to which they may be subjected.The most common container for cryogenic liquids is a double-walled,evacuated container known as a Dewar flask.

(b) Containers and systems containing cryogenic liquids should have pressurerelief mechanisms.

(c) Cylinders and other pressure vessels such as Dewar flasks used for thestorage of cryogenic liquids should not be filled more than 80% of capacity, toprotect against possible thermal expansion of the contents and bursting of thevessel by hydrostatic pressure. If the possibility exists that the temperature ofthe cylinder may increase to above 30C, a lower percentage (i.e., 60 percentcapacity) should be the fill limit.

(d) This SOP must be attached to every liquid nitrogen Dewar.

4.3 Handling and Transport(a) Escape of nitrogen from a Dewar can cause localized oxygen depletion

leading to asphyxiation.

(b) Hence, opening a liquid nitrogen Dewar should be done only in a well-ventilated area. If this is done in a cold room, its door must be left ajar.Alternatively, the Dewar tank is carted out from the cold room to a well-ventilated area when in use.

(c) Refilling a liquid nitrogen Dewar should also be done in an open, well-ventilated area.

(d) Objects that are in contact with cryogenic liquid should be handled with tongsor cryogloves.

(e) When transporting liquid nitrogen in a lift, the Dewar must not beaccompanied. Instead, two people should be assigned to transport theDewars, one to load and one to receive at the destination floor. To preventothers from entering the lift, a Do Not Enter sign should be displayedprominently on the Dewar.

4.4 Training All staff using or handling cryogenic liquids must receive training whichincludes hazards associated with its use, care, selection and use of protectiveequipment and emergency procedures. New users of liquid nitrogen shouldreceive instruction in its use from experienced members of the academic or

technical staff.


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0018 Nov 2010

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4.5 First Aid

(a) Warm the affected area of the body rapidly by immersion in water notexceeding 40C, with body heat, or by exposure to warm air. In the event ofmassive exposure, the emergency shower should be used to warm the body.All clothing must be removed prior to showering. Maintain the affected area ofthe victim at normal body temperature until medical help arrives.

(b) Calm the victim and prevent aggravation of the injury. In the event of frostbiteon the feet, the affected person should not attempt to walk. Do not rub ormassage the affected parts of the body.

(c) Use a mild soap to clean the affected area to prevent infection. Dressingsneed to be applied if the skin is intact.

(d) Flush eyes, if affected, with warm water for 15 minutes.

5. RECORDS

Nil

6. REFERENCES

Nil

Documents

Standard Operating Procedure for Safe Handling of Liquid Nitrogen