Nitrogen is inert, but this does not mean that it is not dangerous - and the evaporation of liquid nitrogen can rapidly displace breathable air with disatrous consequences
Nitrogen is colourless, inert, and odourless.
Without adequate respiratory protection, its effects can also be fatal and, in order to ensure the safety of their employees, many organisations, including laboratories and universities, are turning to the Draeger Polyton 1 gas detection sensors and Regard 1 control system.
Liquid nitrogen expands up to 700 times in air. This means it can quickly displace breathable air and lead to oxygen deprivation.
For this reason, UK legislation requires that all those working in laboratories and other workplace environments should be trained in the use of liquid nitrogen, be provided with good ventilation and have a reliable warning system.
Sadly, two fatalities have already been reported as a result of nitrogen leaks at a New York University and at a Western General Hospital.
In fact, the Health and Safety Executive has issued a warning to all laboratory workers who use liquid nitrogen.
It states that particular emphasis must be paid to the provision of adequate ventilation, suitable warning systems, and systems of work to reduce accidental spillages when working with liquid nitrogen.
According to a report, the warning comes after a laboratory assistant was killed and three others were injured following a leak of liquid nitrogen at a laboratory in Edinburgh.
The effects of oxygen deprivation: some professions, such as aircraft pilots, are more than aware of the dangers of oxygen deprivation and receive specific training on its effects.
One of the major problems is the fact that, in the initial stages, those affected do not notice that they are losing control and, instead, have total confidence in their abilities. Studies have shown that the maximum safe level of oxygen is 23.5% volume, the minimum is 19.5%, and the average oxygen concentration in air is 21%.
At 17% the first signs of deprivation show themselves in the form of judgement errors and, at 16%, anoxia is apparent.
Between 16 and 12% the breathing and pulse rate increases and muscular co-ordination is slightly impaired.
Below 12% and above 10%, emotional upsets, abnormal fatigue upon exertion and disturbed respiration become evident while, between 10 and 6% the sufferer will experience nausea and vomiting, an inability to move freely, and loss of consciousness. Less that 6% volume will bring convulsive movements and gasping respiration, breathing will stop, and a few minutes later heart action will cease.
By using the Draeger system to monitor oxygen levels and to sound an immediate alarm should the oxygen level fall, companies can ensure that they not only meet health and safety requirements but also that they are providing a safe working environment for their employees.
Designed for use in harsh industrial environments, Polyton is an intrinsically safe transmitter for use with electrochemical sensors.
Enabling oxygen as well as toxic gases to be monitored continuously, it indicates gas concentrations as a ppm measurement and can be supplied complete with remote interface.
Reliable and easy to use, Polyton 1 features 4 to 20ma analogue outputs and industry standard two-wire loop powered technology, and works by converting the signal from an electrochemical Draegersensor to a 4 to 20mA signal that is directly proportional to the actual gas concentration.
CE-marked and Cenelec approved, it also affords non-intrusive, one-man calibration.
Regard 1 is a stand alone, wall mounted gas detection controller for use either indoors or outdoors.
Fully configurable to match different sensor requirements, it can be used with two or three wire transmitters and has easy to read front panel controls.
Providing a continuous display, it can also be password protected.
