Laboratory Pressure Vessels / Gas Cylinders Safety

Laboratory Pressure Vessels/Gas Cylinders Safety

1. Purpose

In order to standardize the management of compressed gas cylinders (including Dewar tanks) by schools and institutes (institutes), this specification is specially formulated.

2 Scope of application

This specification applies to the management of experimental compressed gas cylinders in Shanghai University of Science and Technology, including the management of gas cylinders and pressurized dewars. This specification does not

It is suitable for the management of atmospheric gas storage tanks such as liquid nitrogen tanks.

3 Gas cylinder risk identification

1) Gas cylinders are special equipment pressure vessels, which generally have the risk of high pressure and explosion.

2) After the gas in the cylinder leaks, there are potential risks such as suffocation, toxic, flammable, explosive, and freezing.

3) When the valve of the gas cylinder is impacted and leaked, the instantaneous impact force has the energy to penetrate the floor.

4) When the pressure reducing valve of the gas cylinder is not matched, it is prone to leakage risk. If the pressure reducing valve of the oxygen cylinder is selected incorrectly, it is prone to fire.

5) When there is oil, catalyst and other substances at the outlet of the gas cylinder, it is easy to chemically react with the released gas.

6) The colors of common gas cylinders in the laboratory are shown in the table.

7) Gas cylinders must be inspected regularly, and expired gas cylinders must be scrapped. The requirements for the inspection cycle and scrapping life of common gas cylinders are shown in the following table:

4 General regulations on gas cylinder management

4.1 Storage of gas cylinders

1) Compressed gas cylinders entering the campus must be intact, in the correct color, complete with a safety helmet, complete with a seal, and within the validity period.

2) All compressed gas cylinders entering the campus should have a management account. Institutions (institutions) and specific application groups or laboratories should establish pressure vessels safety rules and regulations. 

3) Compressed gas cylinders entering the campus laboratory must be hung with a cylinder management tag. The use of compressed gas cylinder tags should be paid attention to according to the gas cylinder's status. 

4) Gas cylinders entering the laboratory must be fixed.

a) The gas cylinder should be fixed with a fixed bracket. The fixing brackets should be arranged in groups, and it is recommended that each group include two fixing brackets. Each fixed bracket can only be used to fix one compressed gas cylinder. The fixing bracket should be set up according to the wall and nailed to the solid wall.

b) If the wall where the compressed gas cylinders are stored is not suitable for fixing brackets, steel movable gas cylinder fixing brackets should be used instead. Do not use carts as a fixed device for compressed gas cylinders, especially small carts without brakes as a fixed device for compressed gas cylinders.

c) When supplying air to the equipment, air should be supplied from a fixed gas cylinder through a pipeline. The gas cylinder for temporary operation can be used at the gas point, but a reliable fixing method must be adopted. And the gas cylinder must be put back in time after use.

5) Gas cylinders must be stored separately, and it is strictly forbidden to mix incompatible gas cylinders.

a) There are two types of compressed gas cylinders: upright storage and horizontal storage. The compressed gas cylinders in use must be stored upright.

b) The location of gas cylinders should not be close to heat sources and electrical equipment. Different gas cylinders should be stored at a safe distance, see appendix for details.

6) Empty cylinders and solid cylinders should be stored separately, with obvious signs.

7) The storage area should be equipped with a suitable fire extinguisher, and it is strictly forbidden to store it under high temperature or scorching sun.

8) When necessary, gas cylinders should be equipped with alarm devices and safety cabinets.

4.2 Handling of gas cylinders

1) Gas cylinders should be handled with care, and a dedicated gas cylinder transport cart should be used. There should be a device for fixing compressed gas cylinders on the trolley.

2) Gas cylinders should wear safety protective caps and tighten them during transportation.

3) It is strictly forbidden to knock, collide, or strike an arc on the bottle body during transportation.

4) Do not carry incompatible compressed gas cylinders at the same time.

5) The gas cylinder transportation route should avoid areas such as work and life. When handling toxic, harmful, flammable, and explosive gases, pay special attention to avoiding people and content.

6) Gas cylinder handlers must be well trained and wear appropriate personal protective equipment.

4.3 Use of gas cylinders

1) The gas cylinder must be used with a pressure reducing valve. Before selecting a pressure reducing valve, you must verify the type of gas that the pressure reducing valve is suitable for (pay special attention to the pressure valve).

2) After the gas cylinder pressure reducing valve, it should be connected to the experimental device through a pipeline. Compressed gas cylinders and gas pipelines should be posted indicating gas composition and gas flow.

To the label. The position of every 1.5 meters on the straight pipeline, the position of the pipeline turning, the installation of valves and other key accessories or devices on the pipeline

 Labels for gas composition and flow direction should be posted at all locations. Labels should be distinguished by different colors.

3) The compressed gas cylinder gas pipeline should first meet the requirements of no chemical reaction with the conveying gas and ability to withstand the operating pressure.

 Stainless steel pipes are preferred, and medical rubber pipes are strictly prohibited.

4) The piping layout should follow the principle of going high and not going low, and try to pass from above the equipment. If it is indeed necessary to arrange from the ground, the necessary

Necessary protective measures. For gas pipelines arranged on the ground and passing through pedestrian passages, pressure-bearing bridges shall be erected above the pipelines.

5) It is strictly forbidden to use non-safety pipes such as rubber tubes as gas pipelines for gas cylinders.

6) When the gas cylinder is not in use, the safety cap of the gas cylinder should be worn and tightened.

7) It is strictly forbidden to wear catalyst-contaminated gloves to touch the compressed hydrogen cylinder.

8) It is strictly forbidden to wear oil-stained gloves to touch the compressed oxygen cylinder.

9) The gas outlet of the gas cylinder is strictly prohibited from being contaminated with oil and other substances that are prone to chemical reactions.

10) It is strictly forbidden to put gas cylinders on electrical insulators for use.

11) It is strictly forbidden to use leaking gas cylinders.

12) The gas cylinder must retain a safe residual pressure after use to avoid pollution when the gas cylinder is refilled.

13) When moving gas cylinders, special trolleys should be used. It is forbidden to carry oxygen cylinders and acetylene cylinders in the same vehicle.

5 Safe use of Dewar

1) The minimum temperature of the gas (liquid nitrogen, liquid oxygen, liquid argon or liquid carbon dioxide) contained in the Dewar can be minus 196 degrees, so avoid it during use

2) When the pressure of the gas in the Dewar tank is too high, the pressure will be released to the outside and the gas will be discharged. Therefore, keep the storage area ventilated to avoid excessive gas concentration.

3) When receiving the Dewar, it should be confirmed that the gas meets the requirements. The level gauge, pressure gauge, etc. should be checked to ensure that there is no leakage in each part, and the Dewar tank

4) When using Dewar tanks, personal protective equipment should be equipped:

a) Long-sleeved tops, trousers, and shoes that do not leak toes.

b) Experimental work clothes.

c) Protective glasses.

d) Face mask (recommended).

e) Anti-frostbite gloves.

f) Steel toe safety shoes.

5) When the valve and pipeline freeze due to the large amount of gas used, they must be disassembled after being sprayed with water, and must not be violently dismantled.

6) Under normal use, please notify the supplier immediately if the safety valve leaks, the valve leaks, the valve is not tightly closed, the bursting disc bursts, etc.

7) The Dewar tank should be placed upright during use and transportation to avoid tilting. Prevent liquid from being discharged from the safety valve, causing frostbite and damage to the Dewar

Can. Small carts should be used to carry small Dewar tanks. When transporting large Dewar tanks, a suitable cart must be used, and it must be pushed to prevent impact.

6 Safety management of special compressed gas cylinders

6.1 Management of flammable compressed gas cylinders

1) Gas cylinders and pipelines should be kept away from fire, power, high temperature and other areas.

2) The gas cylinders should be placed in a dedicated gas cylinder cabinet or room, and the dedicated cabinet or room should meet the corresponding fire resistance limit design.

3) Gas detection and alarm devices should be installed.

4) After the flammable gas cylinder passes through the pressure regulator, a one-way valve should be installed to prevent backfire. Pipes must use flame-retardant materials, preferably stainless steel material. 

5) Potential leaks may occur, therefore the environment must be well ventilated.

6.2 Management of spontaneously combusted compressed gas cylinders

1) Gas cylinders and pipelines should be kept away from fire, power, high temperature and other areas.

2) Gas cylinders should be installed in separate rooms as far as possible, and strict anti-leakage and ventilation measures should be taken, and gas detection and alarm equipment must be installed.

3) The point of use should be stored separately from the compressed gas cylinder.

4) The gas pipeline connected to the gas cylinder and the point of use must be equipped with a manual quick stop gas supply device.

5) The pipeline must use flame-retardant materials, preferably stainless steel pressure-resistant pipelines.

6.3 Management of toxic compressed gas cylinders

1) The point of use of toxic gas should be set in a separate room from the point of storage of gas cylinders.

2) Gas cylinders should be set up in a separate room, and strict anti-leakage and ventilation measures should be taken. Ventilation design should fully consider the surrounding environment and health impact.

3) The gas cylinder storage room must be equipped with a gas detection and alarm device.

4) There should be obvious warning signs and emergency management guidelines in the vicinity of gas cylinders and pipelines.

5) The gas pipeline connected to the gas cylinder and the point of use must be equipped with a manual quick stop gas supply device.

6) The point of use should be equipped with emergency rescue materials for emergency personnel.

7) There must be a dedicated person responsible for management, independent operation is not allowed, and every operator must undergo professional training.

7 Emergency response

7.1 Emergency of gas cylinder leakage

1) Stop the experiment immediately and understand the characteristics of the leaking gas.

2) Take outdoor convection and exhaust measures in time, and close the valve in time for pipeline leakage.

3) Notify the affected persons to evacuate urgently.

4) Notify the emergency response personnel of the unit and contact the gas supplier for help at the same time.

5) After the emergency is eliminated, the gas cylinders and piping system should be thoroughly investigated, and hidden dangers should be eliminated in time.

6) When rescuing trapped persons, the emergency response team should first understand the environmental conditions to ensure their own safety.