منوی دسته بندی

Liquid nitrogen

Priestley Gas Industries in the field of production and distribution of two strategic products of oxygen and nitrogen in the form of liquid oxygen and liquid nitrogen based on the old experience of producing these products with a purity of at least 7.99% for liquid oxygen and grade 5 and grade 5.5 for nitrogen. Liquid, has the ability to produce in bulk, to meet the order of liquid oxygen and liquid nitrogen from loyal customers of the organization

Nitrogen boils at a lower temperature than oxygen, so oxygen condenses on materials cooled by liquid nitrogen. If these materials are flammable, fire or explosion will occur.

Other hazards of liquid nitrogen and liquid air are due to their low temperature. Here are some dangers of exposure to nitrogen:

1- Suffocation:

When liquid nitrogen boils, it produces gaseous nitrogen, which displaces oxygen in the air. This reduces the oxygen in the air and leads to suffocation indoors.

O2> 19 · 5٪

Normal function

14٪

Decreased physical and mental function without informing the individual

O2 ≤ 14٪

Fainting, anesthesia, death depending on the level and duration of hypoxia

2 – Cold burns:

Cold steam and gas produced when boiling liquid nitrogen can cause cold burns or frostbite due to contact with unprotected skin. Exposure to it may cause respiratory distress and asthma attacks in susceptible individuals.

3 – Fire in the atmosphere enriched with oxygen:

Liquid nitrogen can concentrate atmospheric oxygen. Liquid oxygen creates potentially flammable or explosive conditions by increasing the flammability of many materials (eg solvents, hydrocarbons).

4 – increase in pressure / ice crystal formation:

Due to the high expansion ratio (liquid to gas), if liquid nitrogen evaporates in a closed system, the pressure created will explode. In the absence of a drain valve, ice crystals can form on the valve of storage containers, as water is easily condensed by liquid nitrogen to form ice. This causes pressure to build up in the storage tank.

nitrogen liquid

Liquid nitrogen storage conditions:

In Dewars and storage containers:

Storage containers are classified as pressure vessels and must have a capacity of 50 liters of internal pounds and be used for bulk storage of nitrogen.

Dewars are portable, double-walled containers that do not have an open neck, free ventilation, and no pressure.

Shipping and filling operations:

*** When working with low volumes of liquid nitrogen for laboratory use, containers in accordance with AS 1894 should be used, for example for rapid freezing of samples. Household heat flasks are not suitable for this purpose, as they are not designed to discharge freely and can lead to pressure build-up and subsequent explosion.

*** Only properly trained personnel should be responsible for filling and transferring liquid nitrogen. Measures should be taken to minimize the possibility of splashing as well as exposure to liquids / volatile gases, such as the use of liquid nitrogen pumps and ensuring proper ventilation.

*** Appropriate carts should be used to ensure safe cooling.

*** In addition to the engineering and administrative controls mentioned above, personal protective equipment (PPE) should also be used, on the principle that it should prevent liquid nitrogen from coming into contact with the skin and eyes. This equipment includes:

Thermal insulation gloves.

Safety glasses / full face shield.

Long Sleeve Laboratory Cover.

Apron / long pants.

Shoes are completely enclosed.

Liquid nitrogen should always be tested before being discharged to the factory. Liquid nitrogen suppliers often say there is no need for testing because they use different connections in liquid nitrogen and liquid (or oxygen) trucks, and they have eliminated this confusion. However, in several cases the impossible has occurred and liquid air (or oxygen) has been provided instead of liquid nitrogen. And sometimes these mistakes are discovered by experiment, but we have identified two cases where liquid or oxygen air is fed to the factory. Fortunately, it works in one mode with a high oxygen alarm and in the other with a high temperature alarm. The first incident occurred at a factory where crews always tested regular shipments of nitrogen but did not test overload delivery.
If the alarm due to high oxygen concentration or high temperature misdiagnoses, is there a need for pre-approval testing? Of course, alarms are our last layer of protection. If they fail, there is a possibility of fire or explosion, so we should never intentionally trust them. Our precautionary measures should be as far away from the event as possible.
Nitrogen boils at a lower temperature than oxygen, so oxygen condenses on materials cooled by liquid nitrogen. If these materials are flammable, fire or explosion can occur. In a manufacturing plant, some of the meat consumed had to be ground with cold liquid nitrogen. When the mill was set up, an explosion occurred and two people were killed.

دیدگاهتان را بنویسید