General Standard Operating Procedures

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Standard Operating Procedures for

NMR Facility at UC Berkeley –

Rooms XXX, XXX and XXX.

The ______Lab houses six superconducting magnets in ______, including 300 MHz,400 MHz, and 700 MHz systems. This document describes the potential hazardsassociated with working on and performing routine maintenance on these systems and isintended to be used to train users of the facility. As detailed below, the primary hazardsare the potential for injury resulting from the strong attraction of ferrous objects with thestrong magnetic fields, handling of cryogenic liquids, and the displacement of oxygen asa result of a magnet quench. Additional hazards, including the potential for fire, electricshock, floods, and trip hazards are also discussed.

  • Dial 911 for life threatening emergencies. If using a cell phone, dial 510-642-3333 (UCPD emergencynumber)
  • Health Care Providers

University Health Services/Tang Center

2222 Bancroft Way #4300

Berkeley, CA 94720-4300

(510) 643-7197

Alta Bates Hospital

2450 Ashby Avenue

Berkeley, CA 94705

(510) 204-4444

Emergency contacts:

xxx-xxx-xxxx – office

xxx-xxx-xxxx – home

Safety Contact #1

510-642-2094 – office

xxx-xxx-xxxx – cell

Safety Contact #2

510-xxx-xxxx

xxx-xxx-xxxx – cell

Facilities Management

510-xxx-xxxx – office

Physical plant – campus services

24 – hour maintenance – 642-1032

UC Police, non-emergency – 642-6760

UC Police, emergency – 911 (from desk phone) or 642-3333 (from cell)

Magnetic fields and medical implants

Persons with pacemakers or other electronic, electrical, or mechanical medicalimplants and devices must not enter rooms XXX, XXX, or XXX due to therisk of damage to the device and possible injury or death.

Hazard analysis:

The operation of electronic, electrical, or mechanical medical implants, such as cardiacpacemakers, biostimulators, and neurostimulators may be affected or even stopped in thepresence of either static or changing strong magnetic fields.

Besides electronic, electrical, and mechanical medical implants, other medical surgicalimplants such as aneurysm clips, surgical clips or prostheses, may contain ferromagneticmaterials and therefore would be subject to strong attractive forces near to the NMRmagnet system. This could result in injury or death.

Safety zone and magnetic fields

The safety zone is outside of the 5 Gauss line, marked around each magnet in yellowand black tape. Use extreme caution if it becomes necessary to bring ferromagneticobjects (examples: iron or steel wrenches, other tools, or ferromagnetic electronicequipment such as power supplies) into NMR magnet rooms unless absolutelynecessary, and do not cross the 5 Gauss line with such objects.

Steel gas cylinders and cylinder carts must be kept out of the 5 gauss line of all of themagnets at all times.

Hazard analysis:

Large attractive forces may be exerted on equipment in the proximity of the NMRmagnet system. The force may become large enough to move the equipmentuncontrollably toward the magnet. Small pieces of equipment may become projectiles.

Large equipment (e.g. gas bottles, power supplies) could cause bodies or limbs to becometrapped between the equipment and the magnet, and may damage the magnet and cause aquench.

The closer a ferromagnetic object gets to the magnet, the larger the force. Also, thelarger the equipment mass, the larger the force.

Safe handling of liquid nitrogen and liquid helium

The main hazards associated with handling liquid nitrogen and liquid helium are: A)burns when skin comes into contact with cold pipes or liquid, and b) asphyxiation ifnitrogen or helium has expanded from its liquid form and the gas has displaced oxygen.

To reduce the potential for injury, follow these guidelines:

  • Avoid contact with cold unprotected pipes and vessels when working with liquidnitrogen or liquid helium.
  • Wear proper protective equipment:
  • Dry leather or cryogenic gloves must be worn to avoid cold burns. Thegloves must be loose-fitting so that they can be removed easily.
  • Goggles or a face shield must be worn to protect the eyes and face.
  • Wear closed-toed shoes and long pants while handling cryogens toprotect feet and legs from accidental spills.
  • Metallic objects (e.g. jewelry) should be removed from those parts of the bodythat may come into contact with the liquid.
  • Liquid cryogens pose a potential asphyxiation hazard. Nitrogen expands by afactor of 694 and helium expands by a factor of 740 when changing from theliquid to gas phase. The expanding gas may displace breathable oxygen. Tolimit the asphyxiation hazard, liquid nitrogen and liquid helium should only behandled in well-ventilated areas. Immediately evacuate the room if oxygensensor audible alarm sounds (when oxygen level falls below 19.5%).
  • The extreme cold of liquid nitrogen and helium can cause oxygen to condensefrom the air, resulting in fire danger due to the enriched ignition conditions.
  • Keep cryogen use areas free of combustible materials (paper, cardboard,machine oil, etc) and eliminate any other sources of ignition.
  • Never accompany large quantities of cryogens in the elevator. If the elevatorwere to malfunction, the expanding gas could fill the elevator and pose aserious risk of asphyxiation.
  • Load dewar on elevator, post “No Passengers” sign on the dewar, and retrieve itafter using separate route (stairs or another elevator).
  • When transferring cryogenic liquids, always direct the flow away from others.
  • Never enclose cryogenic liquids within a vessel that can build up pressure (hasno pressure-release mechanism). The expansion of the cryogenic liquid canbuild sufficient pressure to cause an explosion.

Liquid nitrogen fill-station, Room XXX

Automated filling must be conducted while room is unoccupied and door is closed.

Procedure: Leave door open while attaching fill and vent hoses between dewar and fillstation. Activate automated fill sequence, immediately exit the room, and close the door.

Do not enter the room until the fill operation is complete, and the oxygen monitor, whenviewed from the door’s window, indicates there is a safe level of oxygen (>19.5%) in theroom. The oxygen sensor will sound an audible alarm if there is insufficient oxygenwithin the room.

Hazard analysis:

Liquid nitrogen expands by a factor of 694 as it becomes gaseous, displacing oxygenwithin the room. This may lead to a potential for asphyxiation within the room.

Delivery of liquid helium dewars to ______

Passengers should never accompany cryogens (liquid nitrogen or liquid heliumdewars) in an elevator due to the risk of asphyxiation.

Procedure: Attach a sign to the dewar that states: Asphyxiation Hazard, PLEASE DO

NOT ENTER ELEVATOR. Place the dewar in the elevator with the sign clearly visible,select the floor and close the elevator, walk down the stairs, and retrieve the dewar.

Hazard analysis:

The insulation of the liquid helium provided by the dewar is not perfect. As heat entersthe dewar, small amounts of liquid helium are converted to the gaseous state. Heliumexpands by a factor of 740 during this conversion and displaces oxygen. This couldresult in an asphyxiation hazard, if the elevator were to stop for a prolonged period andpassengers were not able to exit the elevator.

Magnet quenches and oxygen sensors

A magnet quenches when the electrical resistance in the coil of wire that forms themagnet suddenly increases. The electrical current is rapidly converted into heat, whichthen causes the liquid helium surrounding the magnet to boil and expand. The rapid boiloffof liquid helium displaces oxygen, which poses an asphyxiation hazard.

The greatest chance of a low-oxygen condition occurs during the quench of a magnet.

All of the liquid helium is converted to gas in a short time. Helium expands by a factorof 740 when transforming from the liquid to gas phase. The expansion poses anasphyxiation risk due to the displacement of oxygen.

Oxygen monitors are located in rooms XXX and XXX. The oxygen levelshould read approximately 20.9% and vary within a few tenths of a percent. TheCal/OSHA standard for minimum oxygen content is 19.5%. When the oxygen leveldrops below 19.5%, a potentially hazardous oxygen-depletion condition exists, and thesensor’s audible alarm sounds. Upon hearing the sensor alarm, all room occupants mustimmediately exit.

The volume of NMR rooms is large enough, and the ventilation rapid enough to restoresufficient oxygen, in event of a quench, within a few minutes. Upon indication of aquench, marked by a loud, hissing release of helium gas, all employees must immediatelyexit the room. The room’s oxygen sensor will indicate low oxygen levels (less than19.5%) by sounding an audible alarm, and will reset (alarm silencing) as the oxygen levelis restored.

In the event of a quench or oxygen sensor alarm:

  • The loud release of gas from the top of the magnet indicates that a quench isoccurring. Also, the oxygen sensor’s audible alarm indicates a low oxygen(<19.5%) level.
  • Leave the room immediately and close the doors.
  • Post signs on the doors stating –MAGNET QUENCH and/or LOW OXYGENDO NOT ENTER.
  • Reassess the oxygen level after 5 minutes, and assure it is restored to normal(20.9%) before re-entering the room.

Compressed gas safety

  • Most cylinders are made of steel, and because of their size, can be violentlyattracted to the magnets. Gas cylinders and gas carts should be kept out of the5 Gauss lines of the magnets at all times. Also, use extreme caution whenchanging cylinder regulators with ferromagnetic wrenches. Do not bringferromagnetic wrenches within the 5 Gauss line for this purpose.
  • Cylinders must be stored in upright positions and immobilized by noncombustiblerestraints (chains) to prevent being knocked over.
  • Cylinder valve caps must be in place when not in use.
  • Cylinders must be moved only by a suitable hand truck.
  • A gas regulator must be attached and in good working order before use.
  • During use, make sure that there are no leaks at the regulator. After use, makesure that the main valve is closed tightly and that there are no leaks.

Hazard analysis:

Compressed gas cylinders containing low grade helium gas are used to pressurize liquidhelium dewars as part of the liquid helium fill procedure. Compressed gas cylinderscontaining high grade liquid helium (research grade) are used to supply the heliumcompressors associated with cryoprobes. The hazards associated with compressed gasuse in this facility are as follows:

  • Steel cylinders are magnetic and can be violently attracted to the magnets.
  • The cylinders contain high pressure gas. In the event the valve is broken, thecylinder can become a lethal rocket.
  • Leaks can lead to the displacement of oxygen and may pose an asphyxiationhazard.

Other potential hazards:

  • Fire:
  • Pull the fire alarm located near the south stairway door, or dial 911 to report afire. Non-magnetic fire extinguishers are located near main NMR room exits.
  • These are Class A extinguishers that use water. They should only be used oncertain types of fires, such as paper, cloth, cardboard etc. Do not use theseextinguishers on electrical chemical fires. Only attempt to extinguish a fire if it issafe to do so. Maintain a safe exit path to the nearest stairwell exit.
  • In the event of smoke or fire in a console, turn off the unit by pressing the redemergency-shutoff switch on the front of the console.
  • Floods, ceiling water leaks:
  • Floods and ceiling water leaks can present a danger of electric shock to theoperator if the floor or electronics becomes wet. Immediately press the redemergency-off switch on the front of the console.
  • Electric shock
  • Consoles contain amplifiers and other electronic equipment that operate at highvoltage (120 V and 208 V).They pose a hazard of RF burns and electrocution. Donot reach inside electronics consoles. If you receive any kind of electrical shock,seek medical attention immediately (call 911 or 510-642-3333 or go to the TangCenter (UC Berkeley police vehicles carry automatic defibrillators)). Even minorshocks can cause injuries that are not immediately apparent.
  • Obstacles
  • Tripping hazards exist in NMR rooms due to cabling between the magnet andconsoles. Be careful when moving around in the lab. Do not stray beyond theyellow-black safety marks on the floor unless you are authorized to do so.

Further procedures requiring additional training

If you need to perform any of the following tasks or use the mentioned systems youmust obtain additional training.

  • Nitrogen Fills
  • Helium Fills
  • Polarizer/Laser System

Attached to this document are the respective standard operating procedures. You mustbe aware of their content and you must have signed them before performing theinvolved tasks.

Training Documentation

NameSignature Date