Unidirectional explosion-proof valve function and installation guide

A unidirectional explosion-proof valve (also known as an explosion-proof flame arrester or explosion isolation valve) is a device used to prevent the propagation of explosions, mainly used in environments with dust or gas explosion hazards. Its core function is to block the spread of flames and pressure waves between pipelines or equipment during an explosion, thereby protecting adjacent equipment and personnel safety.

I. Functions of a Unidirectional Explosion-Proof Valve

Block explosion propagation

When an explosion occurs at one end of the pipeline, the valve's mechanical structure (such as the valve disc) quickly closes, preventing flames and high-pressure shock waves from propagating to the other end.

Protect system integrity

Avoid chain explosion reactions, reduce damage to downstream equipment (such as dust collectors, storage tanks, etc.).

Allow normal material flow

In non-explosion conditions, the valve remains open to ensure the normal passage of gases, dust, and other media.

Passive safety design

No external power or control signals are required; it relies on the pressure of the explosion itself to trigger the action, with high reliability.

II. Installation Points

1. Installation location

Pipeline key nodes : Usually installed on the inlet and outlet pipelines of equipment prone to explosions (such as dust collectors, reaction kettles).

Directionality : Ensure that the valve installation direction is consistent with the direction of media flow (the valve body usually has an arrow marking).

Distance requirement : As close as possible to the equipment being protected (e.g., distance from the dust collector outlet ≤6 meters, refer to standards such as NFPA 68/69 or ATEX).

2. Installation steps

Check valve status

Confirm that the valve type (horizontal or vertical installation), specification (diameter, pressure level) matches the pipeline.

Ensure that the valve disc action is flexible and free from jamming.

Pipeline preparation

Clean any residual material in the pipeline to avoid affecting the valve's sealing performance.

When using flange connections, align the bolt holes and use appropriate gaskets (such as high-temperature graphite gaskets).

Secure the valve

During horizontal installation, the valve disc shaft should be horizontal; during vertical installation, ensure that the valve disc's gravity closing direction is correct.

Bolts must be tightened symmetrically and evenly to prevent leakage.

Auxiliary components

If the system has vibrations, install a support bracket to secure the valve.

In some operating conditions, pressure sensors or interlocking devices need to be installed.

3. Precautions

Do not install in reverse : Incorrect direction will cause valve failure.

Avoid obstruction : Sufficient straight pipe sections must be reserved before and after the valve (usually 5D before and 3D after, where D is the pipe diameter).

Regular maintenance : Check whether the valve disc is stuck, whether the seal is aging, and clean up any accumulated dust or scale.

III. Applicable Standards and Scenarios

Standards : Complies with ATEX 2014/34/EU (EU), NFPA 68/69 (USA), GB/T 15605 (China), etc.

Typical applications : Chemical industry, pharmaceuticals, food processing, metal dust, and other explosion-prone environments.

IV. Differences from Related Equipment

Difference from rupture discs : Rupture discs protect equipment by releasing pressure, while explosion-proof valves focus on blocking propagation.

Difference from fire dampers : Fire dampers are for high temperatures from fires, explosion-proof valves are for explosion impacts.

Correct installation and maintenance of unidirectional explosion-proof valves is crucial to ensuring their effectiveness and should be carried out in accordance with specific operating conditions and regulatory requirements.