Why Do Oxygen Cylinders and Acetylene Cylinders Explode?

Safe use of oxygen cylinders

Transportation

◆ When transporting oxygen cylinders, tighten the safety helmet and wear the cylinder guard ring;

◆ During transportation, load and unload with care to avoid collision;

◆ It is forbidden to roll on the ground or fall from a height;

◆ Combustibles, grease and articles with oil stain shall be prevented from being transported together with oxygen cylinders.

Why Do Oxygen Cylinders and Acetylene Cylinders Explode? 1

Deposit

◆ The oxygen cylinder shall be protected from sunlight, high temperature, open flame and metal splash;

◆ It is prohibited to stack inflammable goods within 10 meters;

◆ The oxygen cylinder should be stored upright, with the cap screwed on to prevent grease and dust from entering the mouth of the cylinder, and fixed with railings and brackets to prevent tilting;

◆ The oxygen cylinder should be more than 1m away from the radiator and other heat sources.

Usage

◆ Before installing the pressure reducing valve, slowly open the cylinder valve, blow off the dust inside and outside the interface, install the pressure reducing valve, and then open the valve for inspection;

◆ During operation, people shall not face the interface at the side of the interface;

◆ Check that the leather pipe joint is free of dust and metal chips before connection;

◆ After the leather tube is removed, it shall not be put up to the sky or on the ground to prevent impurities from entering

◆ The oxygen in the bottle must not be completely used up, and 1~1.5 atmospheres should be reserved to facilitate air flushing inspection and prevent impurities from entering;

◆ In winter, only hot water or steam can be used to defrost the bottle valve, and it is prohibited to use flame for heating or iron hammer;

◆ When working in the same place as the electric welder, insulating pads shall be added at the bottom of the cylinder to prevent electrification of the cylinder;

◆ Metal pipes and equipment in contact with gas cylinders shall be installed with grounding wires to prevent static electricity from causing fire and explosion.

17 FAQs on gas cylinder safety

Why Do Oxygen Cylinders and Acetylene Cylinders Explode? 2

1. Why should acetylene cylinders be kept upright instead of lying down when they are stored and used?

There are four reasons:

Cause 1: The acetylene cylinder is filled with filler and solvent (acetone).

When it is used horizontally, acetone is easy to flow out with the acetylene gas.

This will not only increase the consumption of acetone, but also reduce the combustion temperature, affecting the use.

At the same time, backfire will occur, causing an explosion accident of the acetylene cylinder.

Acetylene in the cylinder is dissolved in acetone solvent under pressure.

When the valve is opened, the pressure decreases, and the dissolved acetylene becomes a gas and is released.

Acetylene cylinders placed horizontally may cause acetone to flow out.

Acetylene dissolved in acetone will quickly volatilize and mix with air to form an explosive mixture. Explosion limit: 2.3% – 72.3% (vol).

Minimum ignition energy: 0.019mJ. It will cause combustion and explosion in case of open fire and heat energy.

It will not only increase the consumption of acetone, but also reduce the combustion temperature, which will affect the use.

At the same time, it will produce backfire, which will lead to the explosion of acetylene cylinders;

In addition, the pressure will blow out the solvent and dissolved acetylene, which will cause the acetylene pressure to rise and explode.

Cause 2: When acetylene cylinders are laid horizontally, they are easy to roll, and the cylinders and other objects are easy to be impacted, which forms excitation energy, leading to the occurrence of acetylene cylinder accidents.

Cause 3: The acetylene cylinder is equipped with shockproof rubber ring to prevent collision during loading, unloading, transportation and use.

The rubber ring is an insulating material, which means that the acetylene cylinder is placed on the electrical insulator horizontally, so that the static electricity generated on the cylinder cannot spread to the ground.

It is gathered on the cylinder, which is easy to generate static sparks.

When acetylene gas leaks, it is very easy to cause combustion and explosion accidents.

Cause 4: When using, the acetylene cylinder valve is equipped with a pressure reducer, flame arrester, and rubber tube.

Because it is easy to roll when lying down, it is easy to damage the pressure reducer, flame arrester, or pull off the rubber tube, causing acetylene gas to leak out, resulting in combustion and explosion.

To sum up, acetylene cylinders must be placed vertically.

2. Do oxygen cylinders have to be upright?

A: It’s not necessary.

3. Why are there anti-dumping measures for gas cylinders?

Answer: Dumping will cause the cylinder valve to fall and escape gas.

Because of the huge reaction force of escaping gas, the cylinder will rush forward or rotate on the ground. If someone is nearby, it will hurt people.

If it is combustible gas, it will cause explosion, which is more serious!

4. Why should oxygen and acetylene cylinders be stored separately?

Answer: Acetylene is flammable, while oxygen is combustion supporting.

If acetylene leaks, it will mix with air and explode violently when meeting sparks or open flames.

The explosion will damage the oxygen cylinder and leak oxygen.

In this case, the combustion-supporting property of oxygen will make the explosion more violent. beyond control. So they can’t be put together.

Why Do Oxygen Cylinders and Acetylene Cylinders Explode? 3

5. Why can’t the bottle be exposed to the sun?

Answer: The temperature of the acetylene cylinder shall not exceed 40 ℃, and the boiling point of acetone shall be 58 ℃.

The higher the temperature is, the faster the acetone volatilizes.

Acetylene will be separated out, which will sharply increase the pressure in the cylinder.

6. Why should there be residual pressure in acetylene cylinders and oxygen cylinders?

Answer: A few kilograms of pressure is left in the bottle to make the pressure inside the bottle greater than the pressure outside the bottle, which can avoid the inflow of other gases and ensure the safety of use.

Because the explosion limit of acetylene is very low, it will explode when it reaches a certain temperature if it is mixed with a little air.

Therefore, there must be a pressure reducing valve at the exhaust port of the acetylene cylinder to prevent air from mixing into the cylinder, otherwise there will be an explosion risk in the next use.

With the pressure-reducing valve, it is necessary to prevent the air pressure in the cylinder from being less than that of the outside air, and to prevent the air from flowing back into the acetylene cylinder.

The oxygen cylinder should retain a residual pressure of not less than 0.098~0.196MPa gauge pressure.

The residual pressure of gauge pressure of 49Kpa~98KPa in winter and 196KPa in summer shall be retained for acetylene cylinders.

7. Why can’t oxygen cylinders, especially the bottle mouth, be contaminated or contacted with grease?

Answer: Because oil, especially unsaturated fat and sour fat, is easy to vaporize and release heat.

The reason why the oil gauze head and oil cloth can self ignite is that oxidation occurs in the air and the heat does not dissipate.

When it reaches the self ignition point, it will cause self ignition.

However, oil vaporizes slowly in the air, and the heat generated is dissipated quickly, which is generally not easy to accumulate heat and ignite spontaneously.

As pure oxygen has extremely strong oxidation, it can promote the violent combustion of combustibles.

When oil and fat meet with pure oxygen, its gasification speed is greatly accelerated. At the same time, a lot of heat is released.

A rapid rise in temperature will soon cause combustion.

If the mouth of the oxygen cylinder is stained with grease, when the oxygen is sprayed rapidly, the grease will be oxidized rapidly, and the heat generated by the friction between the high-pressure air flow and the mouth of the cylinder will further accelerate the oxidation reaction.

Therefore, the grease on the oxygen cylinder or the pressure-reducing valve will cause combustion, or even explosion.

This is the reason why the oxygen cylinder, especially the mouth of the cylinder and the accessories in contact with oxygen, are strictly prohibited from contacting with grease.

Why Do Oxygen Cylinders and Acetylene Cylinders Explode? 4

8. Why do gas cylinders wear caps?

Answer: Most cylinder valves of steel cylinders are made of copper alloy, which is relatively fragile.

Although some of them are made of steel, their structure is smaller than the cylinder body, and they are rotated on the cylinder body to form a right angle between the bottleneck and the cylinder valve joint.

They are both vulnerable points of the cylinder body and prominent points of the cylinder body, which are most vulnerable to mechanical damage or external impact.

In the process of handling, storage and use, if the cylinder falls, falls, rolls or is hit by other hard objects due to careless damage, it is easy to have the joint of the cylinder valve and the bottleneck broken.

Consequences of bottle neck or bottle valve breakage: When the oxygen bottle valve is broken, 150 kg/cm2 of high-pressure gas in the bottle will cause the high-pressure gas in the bottle to lose control and the high-pressure gas will be ejected.

Its reaction force will make the cylinder rush in the opposite direction, which can damage machinery, equipment and buildings, and even cause casualties;

When the acetylene cylinder valve is broken, the flammable gas rushes out, forming explosive gas mixture with the air, and explodes when encountering open fire.

The gas ejected from the cylinder at high speed will cause more serious secondary accidents (such as fire, explosion, poisoning, etc.) depending on the nature of the gas in the cylinder.

If the bottle is filled with combustible gas, the static electricity generated by the intense friction of high-speed jet or other ignition sources may cause combustion and explosion.

On the other hand, when the bottle valve is exposed, it is easy to invade dust or grease substances during handling and storage, which will bring danger.

Wearing a helmet can prevent the contamination and intrusion of dust or grease.

In order to eliminate the above hazards, it is required that the cylinder making unit should be equipped with a safety helmet when the cylinder leaves the factory.

When using gas, unscrew the safety helmet and place it at a fixed place.

After use, put on and tighten the bottle cap in time. Do not throw it around. Never forget to wear safety helmet during handling.

9. Why should acetylene cylinders not be collided?

Answer: The collision will cause the activated carbon to be broken, the expansion space will increase, and the acetylene gas will gather under high pressure, which may cause explosion;

At the same time, when the temperature rises, the gaseous acetylene will polymerize and explode.

10. Why is it required to load and unload cylinders with care, and it is forbidden to throw, roll or collide?

Answer: Due to the severe collision or impact on the gas cylinder, an explosion accident will occur and the consequences will be very serious.

11. Why can’t oxygen cylinders be lifted?

Answer: The oxygen cylinder is a high pressure container. If it falls down carelessly, it is easy to explode.

In case of mass transportation, there is a special container for oxygen cylinders, which is suitable for one-time transportation, loading and unloading of multiple cylinders.

12. Why do acetylene cylinders explode?

Why Do Oxygen Cylinders and Acetylene Cylinders Explode? 5

Answer: The explosion of acetylene cylinder is mainly caused by the rapid rise of temperature and pressure and the decomposition of acetylene.

Characteristics of acetylene decomposition:

If the temperature of the bottle wall rises (starting from the top of the bottle) or abnormal odorous gas with smoke escapes from the open bottle valve after tempering occurs.

It indicates that acetylene has started to decompose. If the acetylene cylinder is directly affected by flame or radiant heat, there is a danger of acetylene decomposition at any time.

Reasons for acetylene decomposition:

(1) Welding tempering;

(2) External heating (there are burning substances near the acetylene cylinder, and the cylinder is hung with tools such as welding gun or cutting gun that have not been extinguished);

(3) The acetylene near the cylinder valve or pressure reducer is on fire;

(4) Severe shock or vibration.

Precautions:

(1) Install the flame arrester;

(2) It is strictly forbidden to expose to the sun, heat the bottle or be close to the heat source;

(3) It is strictly prohibited to hang tools such as welding gun or cutting gun that are not extinguished on the acetylene cylinder;

(4) Handle with care to avoid severe impact or vibration.

13. Why can’t oxygen tape and acetylene hose be mixed?

Answer: Oxygen tape is a high-pressure pipe, and acetylene tape is a low-pressure pipe;

In addition, acetylene pipes sometimes produce slight flashback during use, and there will be carbon deposits in the pipes, which will cause explosion when mixed with oxygen.

14. Why can’t cylinders be mixed?

Answer: If the cylinder is filled with other gases, severe explosion will occur, with very serious consequences.

15. Why should the lower part of the oxygen cylinder be insulated when it is used at the same operation site as electric welding?

Answer: To avoid electrification of gas cylinders.

When working with the electric welder (this is the premise), the bottom of the oxygen cylinder is padded with insulating materials to prevent the cylinder from being electrified.

The metal equipment such as pipes in contact with gas cylinders shall have good grounding devices to prevent burning or explosion accidents caused by static electricity.

16. Why can’t acetylene cylinders be used on insulators?

Answer: The ignition energy of acetylene is only 0.019 mJ. A small electrostatic discharge (several mJ) can ignite (detonate) acetylene.

When acetylene flows or leaks in the gas transmission pipe, it will generate static electricity. Any form of electrostatic discharge may ignite acetylene.

Since acetylene combustion and explosion do not require oxygen, there is a great possibility of explosion after ignition.

If the acetylene cylinder is directly grounded, it will not carry static electricity and will certainly not explode naturally.

17. Why should the copper content of alloy be less than 70% when copper alloy appliances are used for acetylene cylinders?

Answer: After long-term contact with copper and silver, acetylene will generate explosive compounds of copper and silver acetylene, which can cause explosion when subjected to severe vibration or temperature up to 110~120 ℃.

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