Slide 1

Doug Preddy I started working at TRIUMF in 1982 for the experimental facilities group.In1986 I became TRIUMFs first cryogenics operator.I have moved between the Beamlines group and the cryogenics group since then.In January of this year I took over as Group leader for the Beamlines group. This includes the Alignment and Magnet measurements groups at TRIUMF.

Oxygen Deficiency MonitoringatTRIUMFApril 11, 2011Doug PreddyBeamlines Group LeaderTRIUMF

Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Proprit dun consortium duniversits canadiennes, gr en co-entreprise partir dune contribution administre par le Conseil national de recherches CanadaCanadas national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nuclaire et en physique des particulesAccelerating Science for CanadaUn acclrateur de la dmarche scientifique canadienneOxygen Deficiency MonitoringWhat are the effects of an ODH on a human body?Why do we need a monitoring system?Where do we need a monitoring system?What do we expect a monitoring system to do?How do workers respond to an alarm?What are the maintenance and inspection requirements for a monitoring system?

See following slides for answers.

inspections must be done on a yearly basis to ensure a properly operating system.Sensors are to be calibrated at this time if they are found to be out of calibration.Maintenance should be minimal with the sensors and system we have chosen.3There normally is 21% oxygen in the air that we breathe

When the oxygen level drops below 19.5% we consider there to be an Oxygen Deficiency Hazard in the areaWhat is ODHApril 11, 2011 4(%O2 in air)23.5 Maximum Safe Level OSHA21O2 level in air19.5Minimum permissible O2 level (most detectors are set at this level or just above it)15-19First signs of hypoxia. Decreased ability to work strenuously. May induce early symptoms in persons with coronary, pulmonary or circulatory problems.12-14Respiration rate increases with exertion, pulse up, impaired muscular coordination, perception & judgement.10-12Respiration further increases in rate & depth, poor judgement, lips blue.8-10Mental failure, fainting, unconsciousness, ashen face, blueness of lips, nausea, vomiting, inability to move freely.6-86 minutes 50% probability of fatality8 minutes 100% fatal4-6Coma in 40 seconds, convulsions, respiration ceases, death

Effects & Symptoms

April 11, 2011 5Gas releaseCryogenic liquid releaseFireCommon causes of an ODHApril 11, 2011 6

Nitrogen venting , purge gas etc

Lhe or Ln2 spills or leaks flashing into gas will displace oxygen

Fire will use up available oxygen.6One litre liquid converts to ~700 litres of gas Cold nitrogen gas is heavier than air so accumulates at ground level.Cold helium gas is lighter than air so accumulates at ceiling level.When liquid N2 or He is exposed to air the cloudy vapour that you see is condensed moisture, not N2 or He gas. N2 and He gas is invisible and this is the Danger!!!.OHSA recommend at least 6 changes of air per hour when using liquid N2 or He in an enclosed space.

Facts & Figures - Liquid Nitrogen and HeliumApril 11, 20117Occupational Health and Safety Association7The following slides will explain how a low oxygen atmosphere affects a worker.Quick explanation of the physiology of ODH 8

Transport of oxygen in the human body

O2 flows from high concentration to low concentration.

O2 flows from high concentration to low concentration.Concentration of O2 in the lungs is highConcentration of O2 in the tissues and Brain is lower.

Oxygen is transported from the lungs to cells, tissue and brain via Osmosis.Oxygen OsmosisO2 flows from high concentration to low concentration.O2 deficient air is inhaledConcentration of O2 in the tissues and Brain is higher than the lungs

O2 flows from high concentration to low concentration.Concentration of O2 equalises throughout the body.

O2 flows from high concentration to low concentration.O2 deficient air is inhaledConcentration of O2 in the tissues and Brain is higher than the lungs

O2 flows from high concentration to low concentration.

O2 flows from high concentration to low concentration.O2 deficient air is inhaledConcentration of O2 in the tissues and Brain is higher than the lungs

O2 flows from high concentration to low concentration.Concentration of O2 equalises throughout the body.

O2 flows from high concentration to low concentration.O2 deficient air is inhaledConcentration of O2 in the tissues and Brain is higher than the lungs

O2 flows from high concentration to low concentration.

O2 flows from high concentration to low concentration.O2 deficient air is inhaledConcentration of O2 in the tissues and Brain is higher than the lungs

O2 flows from high concentration to low concentration.Concentration of O2 equalises throughout the body.

O2 flows from high concentration to low concentration.O2 deficient air is inhaledConcentration of O2 in the tissues and Brain is higher than the lungs

Reverse OsmosisLungs take O2 from the blood stream which in turn takes it from the brain.Breathing O2 deficient airWhy do we need a ODH system?TRIUMF has a number of areas where large amounts of oxygen displacing gases and cryogenic liquids are stored or delivered. While the storage vessels and pressurized piping are certified by the BC Safety Authority, there still exists the possibility of venting these gases and liquids. This may cause the oxygen concentration in the area of these systems to drop below safe levels for workers. The oxygen deficiency alarm system is primarily in place for the safety of TRIUMF workers, while equipment safety is a secondary consideration.

The workers who died in LN2 leak reports were not overcome with large, quick releases of liquid nitrogen. The nitrogen was being added to the room in a slow, but continuous manner. In most cases the worker that died was the one who was in charge of releasing nitrogen into the room. The worker may not even realize that they are in an oxygen deficient area. One must continually monitor the level of oxygen in rooms where nitrogen is released. At TRIUMF the oxygen levels should be reported back to the main control room which is manned 24/7.. Slow release of helium into a room does not seem to be a problem. The helium will not collect near the floor and it tends to disperse quite readily. The concern for liquid helium is a large, quick release. There are areas that contain large amounts of liquid helium that, if released, would quickly drop the oxygen concentration to a critical level. Low oxygen levels due to helium releases should be monitored close to the cold box and dewar as well as in the compressor building as the ratio of helium released to room volume could be quite high in these rooms.

Remote alarms are essential to the safety of workers.

Handheld monitors do not provide remote alarms.

12When a person enters an oxygen deprived atmosphere the oxygen level in the arterial blood drops to a low level within 5-7 seconds.Loss of consciousness follows in 10-12 seconds.Heart failure and death ensue if person does not receive any oxygen in 2-4 minutes.Holding your breath causes the oxygen in your blood to be used up. If you then inhale the inert atmosphere, suffocation and death will follow in most cases very quickly.

What happens next? 13A risk hazard analysis must be completed for any area that has stored or delivered gases and/or cryogenic liquids that could be released into the area. The analysis would look at a number of criteria that would help define areas that require a fixed low oxygen monitoring system.Is there a sufficient quantity of gas or cryogenic liquid that could be released into the area and cause a low oxygen situation?Is this an area that has people working in it on a regular basis?Is there a ventilation system to ensure an adequate volume of air is exchanged so that a low oxygen concentration is not likely?

Where do we need a ODH system? 14I have an excel spreadsheet to calculate O2 concentrations and possible O2 levels.Still takes a knowledgeable person to decide where to place sensors.Ventilation is to be considered at the lowest normal level in that room.14Local alarmsA fixed low oxygen concentration alarm system would continually monitor the local area and alarm if the oxygen concentration at the sensor drops below 19.5%. The system would alarm locally with a horn/siren and a flashing light. The system would also alarm outside the entrance to each area via a two light system.Remote alarmsThe system would provide annunciation of a low oxygen alarm to the control rooms.Ventilation Ventilation fans could be turned on by the system to provide outside air into an area that shows a low oxygen concentration.

What do we expect the system to do? 15(green light on = safe to enter, red light on = low oxygen alarm therefore no entry to area. No lights on means a system failure = no entry into area).

Fire hazard if fans on.15CET SENSORSHi/low sensor positionsDaisy chained sensorsMaster panel with remote panel in control roomLocal light and horn alarms in areasTwo light warning system outside each areaOur first try at ODH monitoringApril 11, 2011 16CET were electro chemical sensors critical environment technology

High / low mounting of sensors

Daisy chaining provided a single point of failure. It also slows down reading the sensor outputs. (one at a time sequentially) 16We got some things right:

Our first try at ODH monitoringApril 11, 2011 17Lights and horns to annunciate alarm in area.Two light warning system outside each area

Communication between sensors and master panelCommunication between master panel and remote panelsSensors were not the correct typeHazard analysis was not done well enoughThe sensors were not positioned correctlyOur first try at ODH monitoringAril11, 2011 18We got some things wrong:

Initial sensors were electro chemical type. Needed frequent calibration, exchange ( 2yrs), read incorrectly in a Helium environment.Hazard analysis did not take many factors into account. Not a formal process.High level sensors were not useful.18Perform an in depth hazard analysis first.Remove sources of gases by venting dewars etc. outside Selection of proper sensors Build a plc based system.Improve the communication between componentsImprove the display of information on panelsDecide on the proper sensor placementEstablish what can we reuse from the old systemHow we are proceeding nowApril 11, 2011 1919Provide alarms to control room(s)Write procedures for workers to follow in case of alarmsEstablish procedures for non monitored areasEstablish a training program for workers in an area where there is an oxygen deficiency hazard possible.How we are proceeding nowApril 12, 2011 20We have recognized the need for ODH monitoring at TRIUMFOur first effort was not done well enoughA thorough hazard analysis is essential to building a properly working systemSelection of sensors that are compatible with the environment is key to a system that works well

ODH monitoring at TRIUMFApril 11, 2011 21We now have a better understanding of the effects of an ODH on the workers at TRIUMF.There is a need for a proper fixed ODH monitoring system in order to provide a safe work environment for workers.A written response procedure, as well as training for workers also makes the work place safer.Ensuring the system is calibrated and functioning properly is an ongoing process.April 12, 2011 22Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Proprit dun consortium duniversits canadiennes, gr en co-entreprise partir dune contribution administre par le Conseil national de recherches CanadaCanadas national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nuclaire et en physique des particulesTRIUMF: Alberta | British Columbia | Calgary | Carleton | Guelph | Manitoba | McMaster | Montral | Northern British Columbia | Queens | Regina | Saint Marys | Simon Fraser | Toronto | Victoria | YorkThank you!Merci!Questions?