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Safety Protection for N2, H2, O2 and NH2. 2010-7-26 8:22:42    HOT:2968

 
1. Safety Protection for Nitrogen
 
Nitrogen itself is nontoxic, without thrill. Nitrogen breathed in by people shall be discharged out at any of its original form through respiratory tract. However, the increase of nitrogen quantity contains in air will cause the dilution of oxygen and which will affect people’s normal breath while high purity nitrogen will cause suffocation. People who breathed in high purity nitrogen shall be immediately displaced to where the air is fresh as well as arranged for rest and kept him in warmth. If LIN contacts people’s skin, it will cause frostbite. If LIN contacts people’s skin, it shall be flushed immediately with water. If already caused chilblain, he shall be  sent to be cured in hospital.
GN shall be stored in pressured steel cylinder while LIN shall be stored in adiabatic vessels and transported with tanker. For nitrogen is not caustic, at normal temperature, carbon steel, stainless steel, copper, copper alloy, aluminum etc and such kind of universal metal and ordinary plastic material can be adopted as vessel material; as for LIN, nickel steel(90%Ni), stainless steel, copper, brass and valuable bronze can be adopted as vessel material. Under cryogenic condition, Teflon and chlorinated polyethylene polymer can be adopted as vessel material. When 在fire occurs, GN can be used to extinguish the fire, but it is prohibited to fill water into LIN vessels. Waste gas nitrogen can be discharged into atmosphere. 
 
2. Safety Protection for Hydrogen
 
2.1 Technology Regulation for Safe Usage of Gaseous Hydrogen
 
2.1.1 Pipeline and accessories shall adopt products complying with National Standard and Specification as well as adapting to requirements for working pressure and temperature of gaseous hydrogen. Pipeline of gaseous hydrogen shall adopt seamless metal pipeline while it is prohibited to use cast iron pipeline.
 
2.1.2 Normally, welding or other connection modes which can effectively avoid gas leakage shall be adopted for connection of pipelines.
 
2.1.3 There shall be preserved vent pipe, sampling orifice, and purge orifice on pipelines and of which position can meet with the requirements for gas purge and replacement inside of pipelines.
 
2.1.4 If the gaseous hydrogen used as welding, incision, fuel and protection gas etc, there shall be extinguisher set up on each branch pipe of hydrogen consuming equipment.
 
2.1.5 Layout of pipeline shall be accorded with following requirements:
 
A. Gaseous hydrogen pipeline shall be better lay out on stilts and its bracket shall be nonflammable material. Pipeline built on stilts shall not be lay out on the same bracket with cable and electric conduction pipeline. When gaseous hydrogen pipeline, flammable gas pipeline, and gaseous oxygen pipeline are going to be lay out in parallel, there shall be nonflammable material pipeline between to block off them from each other or the net distance between each two of them shall not be less than 250mm. If going to be lay out in layers, the gaseous hydrogen pipelines shall be installed at upper position. Minimum net distance between gaseous hydrogen pipelines and constructions, between gaseous hydrogen pipelines and erections, and other pipelines shall be carried out according to corresponding regulations.
B. Indoor pipeline shall neither be lay out within underground drain nor directly embedded into the underground; outdoor pipeline to be lay out within underground drain shall be adopted with some measurements that can prevent gaseous hydrogen from leakage, accumulation or being mixed into other conduit. Embedded depth of pipelines to be lay out underground shall better not less than 0.7m. Pipeline contains humid gaseous hydrogen shall be lay out under the frost layer of the soil.
C. Bushing shall be set up for pipeline through wall or floorslab. Section of pipe inside of bushing shall be without welding line while space between pipeline and bushing shall be filled with nonflammable material.
D. Pipeline shall not go through underground drain, cloacae, and railroads & automobile roads etc. When pipelines have to go through the above places, bushing shall be set up for each of them.
E. Pipeline shall not go through living room, office, distribution room, instruments room, stair well and other rooms that do not consume gaseous hydrogen. Pipeline should better neither go through suspending ceiling nor technical interlayer, When pipelines have to go through suspending ceiling or technical interlayer, safety measurements shall be adopted for it.
 
2.1.6 Pipeline to be built on stilts indoor or outdoor or pipelines to be embedded into the underground as well as junction station and gas cylinder connected with it all shall be straddling to connect with each other and earthing. While straddling and earthing measurements shall be implemented as per related current national regulations.
 
2.1.7 Vent pipe
 
A. Vent valve, safety valve, and ductwork for storage tank of gaseous hydrogen all shall be set up with vent pipes.
B. Vent pipes shall be made of metal material. However, plastic pipe or rubber pipe does not allow using.
C. Vent pipe shall be set up with extinguisher. And if condition allows, it can be connected with fire-extinguishing steam or inert gases pipelines to avoid it catching fire.
D. Exit of indoor vent pipe shall be 2m higher than the building. Vent pipe of outdoor equipment shall be 2m higher than that the highest manipulative equipments nearby.
E. Vent pipe shall be earthing with static means and within the protective scope of lightning conductor.
F. There shall be measurements preventing rain and snow from invading into as well as preventing sundries ab extra from blocking up the vent pipes.
 
2.2 Safety outline for operation of gaseous hydrogen system
 
2.2.1 Oxygen content in gaseous hydrogen input the system should not exceed 0.5%.
 
2.2.2 Knock on, overpressure, and minus pressure are prohibited when the gaseous hydrogen system is running.
 
2.2.3 Once pipeline, valves and water seal device frost, it only can be defrosting with warm water or steam heating. Defrosting by firing through flaming fire is strictly prohibited.
 
2.2.4 Leakage inspection on connection points of equipments, pipelines and valves etc can be done with suds or portable flammable gas anti-blast tester while fire is prohibited to use.
 
2.2.5 It is prohibited to vent gaseous hydrogen indoors. Purging, washing, replacement, vent, and pressure reducing all of these shall be discharged through vent pipe.
 
2.2.6 If gaseous hydrogen leaking or accumulating massively, it shall cut off gas source to ventilate the equipment while any operations which may cause fire is highly prohibited.
 
2.2.7 Pressure maintaining test, cleanout and airtight test shall be performed on those gaseous hydrogen systems newly installed or heavy repaired and of which could only put into use as long as it accords with relative inspection requirements after the tests.
 
.2.8 Normally, means such as GN(or other inert gases) replacement or water-filling exhaust can be adopted for purging, washing and replacement on gaseous hydrogen system.
 
A. Oxygen contains in gaseous hydrogen should not exceed 3%.
B. Replacement shall be thorough to avoid remnant gas remains at the end of the dead corner.
C. After replacement, oxygen or hydrogen content in the system shall be continuously accepted for three times.
 
2.2.9 Examine and repair on gaseous hydrogen system with using fire, it shall ensure that  highest gaseous hydrogen content inside of system and within fire using area shall not exceed 0.4%.
 
2.2.10  Prevent fire and other kindling energy source while forbidden to use electric cooker, electric drill, stove, and blowtorch such kinds of fire producing and heating producing facilities and objects; It is forbidden to bring kindling into forbidden zone; Select tools made of copper or beryllium-copper alloy; Wear cotton uniform and antistatic shoes.
 
3. Safety Protection on Oxygen
 
Oxygen is one of basis contains in air and of whose cubage accounts for 21.0% of normal air. Meanwhile, oxygen is internal composition of all propagation. But, it will do harms to people as its concentration lower or higher than normal level. If pressure of distributed oxygen higher than required value, it will cause oxygen toxicosis.
At normal pressure, if concentration of oxygen exceeds 40%, it will cause possibility of oxygen toxicosis. There are two symptoms towards people who have got oxygen toxicosis:
 
(1.)  Lung—it mainly happens when pressure of distributed oxygen is 1-2 bars which amounts to breathe in oxygen with concentration of 40-60%. At the very beginning, poisoned people may feel something uneasy upon his breastbone accompanied by gently coughs; furthermore, he may feel his chest suffocating, back breastbone cauterizing as well as breath more difficult and cough stronger. In severe situation, it will cause pulmonary edema and even suffocation.
 
(2.)  Neurosis—it mainly happens as pressure of distributed oxygen higher than that of 3 bar and which amounts to breathe in oxygen with concentration of 80% above. At the very beginning, poisoned people may feel mouth and lips or facial muscle twitch, complexion gets grey, blackout, heart beats faster, and prostration followed by entasia/epilepsy from head to foot, coma, breath crocks up and then die.
Medical treatment for oxygen toxicosis should be done in time while enhance ventilation,  turn to breathe in air, sleep quietly, keep respiratory tract unobstructed, bestow patient mitigative and convulsions-preventing medications, and prevent lung from further infection.  To cure anoxia, the key is to eliminate the causations lead to it and prevent hydrocephalus. Commonly, people should withdraw from the locale and breathe in gaseous oxygen which better to be presented with positive pressure. If condition permits, high pressure oxygen shall be adopted to cure people. If heart stops beating, manual breath and heart massage shall be done for the patient to make them recovery as soon as possible.
Liquid oxygen can deaden skin, and its tissues to bring about frostbite. Once the skin contact liquid oxygen, it shall be flushed with water immediately and heavy injured people should be sent to make a diagnosis and give treatment in hospital. Gaseous oxygen vaporized from liquid oxygen is easy to be adsorbed by clothes and of which will cause rapid combustion without exception once it meets anyone kinds of flaming matters.
Once oxygen supply is not enough or metabolizing process of oxygen inside of body occurs some obstacles which cause that people cannot get sufficient oxygen or utilize oxygen so as to engender a chain of effects even endanger people’s life. That is “anoxia”. Following are symptoms and aftereffects under different anoxic conditions:
 
O2 Content
(Cubage percentage)
Symptoms(At atmospheric pressure)
15-19%
Endurance declines and may cause early pathological changes to coronal, lung and circulation system.
12-14%
Hurry breath while faster pulse and may damage judgment capability of balance system.
10-12%
Breath becomes further hurry and judgment capability extremely weak as well as mouth and lips pastiness.
8-10%
Spiritual trance, going faint, consciousness lost, flushing, mouth and lips pastiness, nausea, vomit.
6-8%
People stay under this condition more than eight minutes will die. People stayed under this condition less than 4-5 minutes could recuperate after medical treatment.
4-6%
People stay under this condition for 40 seconds will cause coma, convulsion, breath cease, and death.
 
Liquid oxygen shall be stored and transported with tanker or . When store, it must be placed at where isolated with combustible material while avoid being heated. Liquid oxygen tanker had better placed outdoors. Though oxygen is no causticity, aluminum alloy shall be used as least as possible. If contains moisture, it will erode the metal. Therefore, moisture removal operations shall be performed on all equipments. Available material such as stainless steel, copper, copper alloy, nickel, nickel alloy, glass and etc. Try not to use carbon steel and low alloy steel. As for liquid oxygen, Teflon, chlorotrifluoroethylene polymers, and fluorine rubber shall be used for it while try not to use polyethylene and polypropylene such kinds of combustible material. Once fire occurs and it is too late to transfer the tanker, it shall be poured and cooled down with water to avoid possible explosion by heating as well as avoid liquid oxygen effluent after explosion to further the fire. However, when pour water onto the tanker, by all means, rescuers shall try their best not to pour water onto safety valve and cause its malfunction.
As leaked liquid oxygen cause combustion of wood, and paper etc, if possible, it shall cut off airflow firstly to hold out overflow and leakage, and then to extinguish fire with sufficient water. When the fire is caused due to liquid oxygen encountered with other liquid fuel, fire fighting procedures shall be performed as follows: When fire caused due to overflowed and leaked liquid oxygen flowed onto a great deal of fuel, in this situation, it shall cut off source of liquid fuel firstly, and then to extinguish the fire. When liquid fuel and liquid oxygen has been already mixed together while does not cause fire yet, it should cut off all source of fire immediately and get out of dangerous area as rapidly as possible to let the liquid oxygen vaporize automatically. If it is water-soluble fuel, it can be diluted with water to hold down the fire but this method is inapplicable to those non water-soluble fuel, and must wait until all liquid oxygen already vaporized completely and then extinguish the fire with proper fire extinguisher.
 
4. Safety Protection for Ammonia
 
4.1 Fatalness when ammonia mixed with other substance as follows:
 
Title of dangerous substance as mixed
Chemistry formula
Criticality
Summary
Potassium chlorate
KClO3
A
With fatalness of stimulating reaction
Sodium chlorate
NaClO3
A
With fatalness of stimulating reaction
Sodium chlorate
NaClO4
A
With fatalness of stimulating reaction
Hydrogen peroxide
H2O2
A
 
Sodium dioxide
Na2O2
B
 
Ammonium nitrate
NH4NO3
A
 
Sodium nitrate
NaNO3
B
 
Potassium permanganate
KMnO4
C
 
Acetaldehyde
CH3CHO
C
With fatalness of stimulating reaction
Nitric acid
HNO3
A
Catch fire once contact gas
Sulfuric acid
H2SO4
C
 
Chromic oxide
CrO3
B
Engender incandescence as CrO3 decompounds
Potassium chlorite
KCLO2
A
Fatalness of becoming more sensitive to impact(engender NH4CLO2)
Sodium chlorite
NaClO2
A
Fatalness of becoming more sensitive to impact(engender NH4CLO2)
Sodium bromate
NaBrO3
A
With fatalness of stimulating reaction
Hypochlorous acid
HClO
B
With fatalness of explosion
 
4.2 Toxicity
 
Max allowable concentration: 25ppm (18mg /m3). Ammonia mostly is breathed in through respiratory tract and of which also could be adsorbed through skin.
Breathing in high purity gaseous ammonia will cause sneeze, saliva overflow, cough, nausea, headache, sweat, facial hyperemia, chest ache, hurry breath, frequent emiction, blackout, sense of suffocation, uneasiness, stomach-ache, and anuresis etc. It stimulates eyes and of which will cause lachrymation, eye sore, seeing obstacle. As developed into chrono toxicosis, patient may suffer symptoms such as headache, nightmare, inappetence, prone to be excited, chrono conjunctivitis, chrono bronchitis, bloody phlegm, and tinnitus etc. Patient who breathed in gaseous ammonia should be transferred to safety zone to arrange for rest and keep warm. If they cough, they could take in some codeine. If his breath is abnormally slow or ceased, oxygen therapy treatment or manual breath measurements should be performed on him and call the doctors come to make a diagnosis and give treatment immediately.
If the skin contacted with ammonia, which may stimulate the skin and cause rubefaction as well as cause burn and decay to the skin. Once the skin contacted with ammonia, it is better to flush the skin immediately with water and then wash it clean with suds, next cover the skin with dressing soaked by acetum, citric acid, tartaric acid and hydrochloric acid with concentration of 5% or boracic acid solution with concentration of 2% above can be compressed on the affected part. As frostbite by liquid ammonia, first, it shall be gone through thaw and take off frozen closes. It shall be noticed not to divulse the skin when taking off the closes, especially pay attention to armpit and perineum such kinds of humid parts. If eye injured, first, flush it with water or alum solution with concentration of 0.5%-1%, then drip petroleum jelly or olive oil into eyes. If eye acutely aches, please drip about 1-2 drips of Novocain solution with concentration of 1% or 1 drip of adrenalin solution(1:1000) with concentration of 0.5% into eyes.
 
4.3 Safety Protection Measurements
 
When have to contact ammonia of low concentration, it is required to wear gas defence respirator for ammonia; When have to contact ammonia of high concentration, it is required to wear air-feed face guard. When dealing with water-solubility liquor, it is required to wear tall rubber overshoes, safety eyeglass, and rubber glove etc at one time.
Under room temperature or high temperature, hydrolyze or not, the ammonia itself erodes some metal material. Therefore, it is very necessary to select out proper material. In dry gaseous ammonia, stainless steel, iron-silicon alloy, copper, and zinc alloy, magnesium alloy, nickel, monel, nickel-based alloy, silver and silver alloy, and tantalum. In humid gaseous ammonia, copper and copper-zinc alloy, nickel, monel, silver and silver alloy should not be used, but carbon steel could be utilized. Teflon, PCTFE, polyethylene, hevea rubber, nitrile rubber, neoprene, Hai palun, butyl, silicone rubber, and oxidised rubber.
Cylinder stored ammonia should be placed outdoors where the surroundings is cool and  dry while the ventilation is good. To avoid sunshine directly contact the cylinder as well as avoid any of possible impact. If store outdoors, it should be separated from other chemical medicine especially oxidation gas, halogen and the acid while the equipment pipelines should be strictly sealed. While cloth soaked by suds and hydrochloric acid (which brings ammonium chloride white smoke when contact chlorine) or its odour could be used to inspect leakage of the pipelines.
Waste ammonia gas should be neutralized with hydrochloric acid after it is adsorbed into water while it also could be drained into sewer after diluted with abundant water. Not only Hydrochloric acid but also sulfuric acid and other acids could be used as corrective. Once leakage of ammonia occurs, first, wet straw mat shall be covered on leaking point or on ammonia liquor leaked; then flush it with hose from afar. Once gaseous ammonia spouts massively, water mist should be sprayed to adsorb leaked ammonia from afar. Adhered liquor should be flushed with abundant water or be neutralized with water containing hydrochloric acid. Once catch fire, firstly valve of steel cylinder should be cut off to stop gas leaking. Water mist fire extinguisher, carbon dioxide fire extinguisher, froth fire extinguisher and dry powder fire extinguisher could be used to extinguish the fire.

Suzhou Xinglu Air Separation Plant Science And Technology Development Co.,Ltd.
Address: No.7 Qilu Road,Suzhou,Jiangsu
TEL: 0512-65769056 FAX: 0512-65767057
E-mail: overseas@xlasp.com
 
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