Technical requirements for automatically activated fire extinguishers in Vietnam

Hello, Lawnet would like to answer as follows:

1. What is an automatically activated fire extinguisher?

According to the provisions of Section 3.1 of TCVN 12314-1:2018, an automatically activated fire extinguisher is a fire extinguisher that uses fire extinguishing powder and automatically activates.
when there is an impact of environmental temperature or the fire's flame is large enough to exceed the activation threshold (working temperature).

Spraying fire extinguishing agents can be done by:

- Propellant gas is compressed directly in the tank (the pressure inside the tank containing the fire extinguishing agent remains constant)

- The action of the cylinder when pushed (pressurization at the time of use by releasing pressurized gas in a separate high-pressure container).

- At the same time, automatically activated fire extinguishers are designed with a hanging mechanism (ceiling, wall, under the roof...).

Operating principle of an automatically activated fire extinguisher

According to the provisions of Section 3.3 and Section 3.3.1 of TCVN 12314-1:2018, the fire extinguisher automatically activates and operates on a specific sensor principle:

- The part that automatically receives the impact of heat or flame from a fire thanks to the heat response element.

- The heat-responsive element can be a molten metal or a glass bulb.

- Parts with details that automatically melt due to the impact of a heat source or the flame of a fire.

2. Technical requirements for automatically activated fire extinguishers in Vietnam

General requirements for automatically activated fire extinguishers

According to Section 4.1, Standard TCVN 12314-1:2018 stipulates general requirements for automatically activated fire extinguishers as follows:

- Easy to operate, check, and maintain, it has a durable structure over time.

- Does not pose a danger to users.

- Attaching accessories must not affect the function of the device and must not be loose or damaged when using the device.

- All parts that need to be removed during operation must be able to be easily removed without affecting the spraying of fire extinguishing powder.

- Fire extinguishers that automatically activate the injection of a fire extinguishing agent using compressed propellant gas directly in the tank must be equipped with a pressure gauge to indicate the pressure value in the tank.

- The total weight of the automatically activated fire extinguisher must ensure an error of no more than ± 5% of the design index.

- The suspension mechanism for automatic fire extinguisher activation of the hanging type must be sturdy and safe.

- When tested according to the provisions of Section 5.4 of the TCVN 12314-1:2018 Standard, spray efficiency and spray time must comply with the following requirements:

+ Spray angle must be suitable for firefighting.

+ The amount of fire extinguishing powder sprayed from the tank must be greater than 90% of the loaded mass or volume.

+ Fire extinguishing powder injection time must be within ± 30% of the design value (value stated on the label and technical documents of the tank).

- Effectively extinguish fires

+ For hanging type automatic fire extinguishers, they must comply with all type A and type B fire extinguishing tests described in Sections 5.5.1, 5.5.2, and 5.5.3 of the TCVN 12314-1 Standard :2018, each test is conducted only once for one batch of product.

Technical requirements for materials of automatically activated fire extinguishers in Vietnam

According to Section 4.3.2 of Standard TCVN 12314-1:2018, the materials of automatically activated fire extinguishers are specified as follows:

- Tank made of welded low-carbon steel

+ The materials for making the vessel must be weldable and have a maximum content by weight of carbon of 0.25%, sulfur of 0.05%, and phosphorus of 0.05%.

+ The weld filler material must be compatible with the steel to give the weld joint properties equivalent to those specified for the basic steel plate.

+ The stress of the cylindrical or spherical fire extinguisher body (S) calculated according to the formula below must not be less than 80% of the maximum yield point or maximum breaking strength of the body material. In this case, the maximum measured breaking strength of the material will be used if there is no official manufacturer's specification stating the maximum yield point or maximum breaking strength.

++ For cylindrical vessels: S = P.d/2t

++ For spherical vessels: S = P.d/4t

In there:

d is the outside diameter of the extinguisher or the largest diagonal of the fire extinguisher body for non-cylindrical extinguisher bodies, in mm;

P is the tank test pressure, in MPa.

t is the thickness of the tank shell, in mm.

- Stainless steel tank

+ Stainless steel lids and bottoms must be stamped from fully annealed billets.

+ Only use austenitic stainless steel with a maximum carbon content of 0.03% by weight.

Note: An example of the above stainless steel is ASTM A240, grade 304L (UNS designation S30403).

- Aluminum tank

+ Aluminum tanks must have a non-jointed, non-welded structure.

- Tanks made of other materials must conform to pressure tank standards as well as requirements for working pressure and minimum burst pressure.

More details can be found in Standard TCVN 12314-1:2018.

Best regards!

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