Standard Operating Procedure (SOP)

Transcription

1 Standard Operating Procedure (SOP) For using Cryogenics (Liquid Nitrogen) #1 General Process Description Liquid nitrogen is used for many different applications in the department of Materials Science and Engineering. Liquid Nitrogen used for undergraduate labs (quenching, thermodynamics, heat capacity of metals, and cooling Charpys for Ductile to Brittle Transition). Liquid Nitrogen is also used for instrumentations (Glow Discharge Optical Emission Spectrometry and Inductively Coupled Plasma) which uses the gas produced from the boiling of the Liquid nitrogen in a high pressure liquid nitrogen dewar. All work described in this SOP will be conducted in rooms JHE 134, 240, 244, 245, or 247. You MUST have WHMIS training prior to working in the lab. Contact Person is Ed McCaffery Laboratory Manager (Room JHE 248 ext 24985). #2 Hazards of Liquid Nitrogen/ Class of Hazard Although nitrogen is nontoxic and inert, it can act as a simple asphyxiant by displacing the oxygen in air to levels below that required to support life. Inhalation of nitrogen in excessive amounts can cause dizziness, nausea, vomiting, loss of consciousness, and death. Death may result from errors in judgment, confusion, or loss of consciousness that prevents self-rescue. At low oxygen concentrations, unconsciousness and death may occur in seconds and without warning. Personnel, including rescue workers, should not enter areas where the oxygen concentration is below 19.5%, unless provided with a selfcontained breathing apparatus or air-line respirator. Liquid nitrogen temperature is (-196 C), and at this temperature cause severe tissue damage if skin comes in contact with the liquid. #3 Personal Protective Equipment (PPE) One must be thoroughly familiar with the properties and safety considerations before handling a cryogenic liquid and its associated equipment. The eyes are the most sensitive body part to the extreme cold of the liquid and vapors of cryogenic liquids. The recommended personal protective equipment for handling cryogens are: 1. Full Face Shield over safety glasses, 2. Loose-fitting thermal insulated or leather gloves 3. Long sleeve shirts, and trousers without cuffs. 4. In addition, safety shoes are recommended for people involved in the handling of containers. Depending on the application, special clothing suitable for that application may be advisable. NO Sandals or Open Toed Shoes!

2 A special note on insulated gloves: Gloves should be loose-fitting so they are able to be quickly removed if cryogenic liquid is spilled on them. Insulated gloves are not made to permit the hands to be put into a cryogenic liquid. They will only provide short-term protection from accidental contact with the liquid. In emergency situations, self-contained breathing apparatus (SCBA) may be required. #4 Engineering / Ventilation Controls Store and use this product with adequate ventilation. Do not store in a confined space. Cryogenic containers are equipped with pressure relief devices to control internal pressure #5 Special Handling Procedures and Storage Requirements Under normal conditions, these containers will periodically vent product. Do not plug, remove, or tamper with any pressure relief device. Never allow any unprotected part of the body to come in contact with uninsulated pipes or equipment that contains cryogenic product. The extremely cold metal will cause the flesh to stick fast and tear when one attempts to withdraw from it. Use a suitable hand truck for container movement. Containers should be handled and stored in an upright position. Do not drop, tip, or roll containers on their sides. Do not remove or interchange connections. Contact the vendor if you experience any difficulty operating the container valve or with the container connections. Discontinue use. Use the proper connection. DO NOT USE ADAPTERS! Use piping and equipment designed to withstand the pressures to be encountered. On gas withdrawal systems, use a check valve or other protective apparatus in any line or piping from the container to prevent reverse flow. To prevent cryogenic liquids or cold gas from being trapped in piping between valves, the piping should be equipped with pressure relief devices. Only transfer lines designed for use with cryogenic liquids should be used. Some elastomers and metals such as carbon steel may become brittle at low temperatures and will easily fracture. These materials must be avoided in cryogenic service. It is recommended that all vents be piped to the exterior of the building or to a well ventilated indoor space.

3 #6 Accident Procedures People suffering from lack of oxygen should be moved to fresh air. If the victim is not breathing, administer artificial respiration have someone call 88. If breathing is difficult, administer oxygen. Obtain immediate medical attention. Self-contained breathing apparatus (SCBA) may be required to prevent asphyxiation of rescue personnel. For skin contact with cryogenic liquid nitrogen, remove any clothing that may restrict circulation to the frozen area. Do not rub frozen parts, as tissue damage may result. As soon as practical, place the affected area in a warm water bath that has a temperature not in excess of 105 F (40 C). Never use dry heat. Call a physician as soon as possible. Frozen tissue is painless and appears waxy with a possible yellow color. It will become swollen, painful, and prone to infection when thawed. If the frozen part of the body has been thawed, cover the area with a dry sterile dressing with a large bulky protective covering, pending medical care. In the case of massive exposure, remove clothing while showering the victim with warm water. Call a physician immediately. If the eyes are exposed to the extreme cold of the liquid nitrogen or its vapors, immediately warm the frostbite area with warm water not exceeding 105 F (40 C) and seek immediate medical attention. Contact Emergency Response (88), then and Lisa Morine Ext and Ed McCaffery Ext #7 Waste Disposal Not Applicable #8 Training requirements Prior to entering and working in the laboratory, you must have completed the EOHSS WHMIS training. You will have to retain training documentation for at least one year. Any person conducting work using this SOP must receive training on the contents of this SOP. #9 Approval Required All research staff must be trained prior to starting work with the cryogenics. Under no circumstances it is allowed to work with the liquid nitrogen, while being alone in the laboratory. Always ask a second person to be in the lab with you. If you have to work with liquid nitrogen and you are alone, you have to ask for approval from your Supervisor then Laboratory Manager Ed McCaffery. #10 Decontamination N/A.

4 #11 Designated Area Upon leaving a designated work area, remove any personal protective equipment worn and wash hands. After each use (or day), wipe down the immediate work area. At the end of each project, thoroughly decontaminate the designated area before resuming normal laboratory work in the area. #12 Precise Process Description Always handle cryogenic liquids carefully. Their extremely low temperatures can produce cryogenic burns of the skin and freeze underlying tissue. When spilled on a surface, they tend to spread as far as the quantity of liquid spilled and the physical confines of the area permit. They can cool large areas. The vapors coming from these liquids are also extremely cold and can produce burns. Exposure to these cold gases, which is too brief to affect the skin of the face or hands, may affect delicate tissues, such as the eyes. Stand clear of boiling and splashing liquid and the cold vapors that are released. Boiling and splashing always occur when filling a warm container or when inserting objects into the liquid. Always perform these operations slowly to minimize the splashing and boiling. Never allow any unprotected part of your body to touch uninsulated pipes or vessels containing cryogenic liquids. The extremely cold material may stick fast to skin and tear the flesh when you attempt to withdraw it. Even nonmetallic materials are dangerous to touch at these low temperatures. Use tongs to immerse and remove objects from cryogenic liquids. In addition to the hazards of frostbite or flesh sticking to cold materials, objects that are soft and pliable at room temperature, such as rubber or plastics, are easily broken because they turn brittle at low temperatures and may break when stressed.

5 Laboratory Spill Response Procedures Health Threatening Situation - In the event of an imminent or actual health-threatening emergency (threatening local or public health, safety, or welfare; or the environment outside the immediate area): 1) CALL 88 FOR THE EMERGENCY RESPONSE REMAIN IN THE AREA TO ADVISE RESPONDERS. 2) ACTIVATE LOCAL ALARM SYSTEMS 3) Once personal safety is established, call EOHSS at Ext and proceed with local notifications, below. Non-Health Threatening Situation In the event of a major burn or asphyxiation: 1) Notify McMaster Responders: Call 88 (24 hours/day, 7 days/week), then 2) Provide local notifications: Name Phone Number Title Ed McCaffery Ext Lab Manager/ Principal Investigator Lisa Morine Ext EOHSS Local Response Situation In the event of a minor burn: 1) Notify personnel in the area and restrict access. Disclaimer: The SOP as written contains our best understanding at this time on how to work safely with this piece of equipment. When new information is found that would improve the safe use of this equipment it will be added in a timely manner. As it stands we cannot be held liable for misuse or abuse of these instructions through negligence on the user s part or based on the content of these notes.