Bonfiglioli VF-W series ATEX explosion-proof reducer selection guide

Bonfiglioli VF-W series ATEX worm gear reducer: professional selection and explosion-proof application

In industrial fields such as chemical, petroleum, natural gas, grain processing, and pharmaceuticals where there is a potential for explosive environments, the safety and reliability of driving equipment are the primary considerations in engineering design. As a globally renowned provider of power transmission solutions, Bonfiglioli's VF-W series worm gear reducer is an ideal choice for such application scenarios due to its compact structure, large speed ratio range, and comprehensive ATEX explosion-proof certification. This article aims to provide engineers with a systematic technical reference, covering core aspects such as ATEX directive requirements, gearbox selection calculations, installation specifications, and load verification.

Product positioning of ATEX explosion-proof system and VF-W series

According to the EU ATEX Directive 2014/34/EU, a potentially explosive environment is defined as an area where flammable substances (gases, vapors, dust) mix with air and can spread combustion upon contact with a source of ignition under specific conditions. Equipment manufacturers must select products of the corresponding category based on the risk level of their installation area.

1. Regional division and equipment category

Zone 0/20: Continuous or long-term presence of explosive environment (highest risk).

Zone 1/21: Occasional occurrence during normal operation (moderate risk).

Zone 2/22: It is unlikely to occur during normal operation, and even if it does occur, it only exists briefly (with low risk).

The Bonfiglioli VF-W series ATEX gearbox is suitable for zones 1, 21, 2, and 22 (corresponding to equipment categories 2G/3G and 2D/3D). The manual clearly states that this series of products is not suitable for high-risk areas in Group I and Group II Category 1 mines.

2. Temperature Class and Surface Temperature Limits

For gas environments, the temperature level (T level) determines the maximum allowable surface temperature of the equipment, which must be lower than the ignition source temperature. The VF-W series can provide:

T3: Maximum surface temperature ≤ 200 ℃

T4: Maximum surface temperature ≤ 135 ℃ (applicable to higher requirements)

For dust environments (Class D), the self ignition of the dust layer is prevented by limiting the surface temperature of the shell (such as 130 ℃ or 160 ℃). When selecting, users need to clearly indicate the required temperature level in the ordering code.

Structural characteristics and installation requirements of VF-W series

1. Core elements of explosion-proof design

All sealing rings come standard with FKM, which is resistant to high temperatures and chemical corrosion.

No plastic parts, avoiding the risk of static electricity accumulation or melting.

Equipped with oil level check plugs, breathable plugs, and drain plugs for easy daily maintenance.

The nameplate clearly indicates the product category, temperature level, and certification number to ensure traceability on site.

2. Installation positions

The VF series (without base) and W series (with base) support multiple installation orientations, including B3 (horizontal), B6/B7/B8 (vertical, different shaft directions), and V5/V6 (suspended). Key limitations:

The installation location must be specified at the time of ordering and indicated on the nameplate. It is strictly prohibited to change the installation direction without the approval of Bonfiglioli's technical department.

Specifically, when the W110 machine base is installed in the V5/V6 position and equipped with a B14 flange motor, no oil is added at the factory. Users need to add the specified lubricating oil according to the actual installation direction.

The input shaft speed shall not exceed 1500 min ⁻¹ (four pole motor). If used in conjunction with a variable frequency motor, the maximum frequency must be limited by parameter settings to prevent overspeed.

3. Environmental temperature limit

The long-term operating environment temperature allowed for ATEX equipment is -20 ℃~+40 ℃. If it exceeds this range, the thermal power needs to be recalculated and the manufacturer consulted.

Selection process and calculation of gearbox

Whether the selection is correct directly affects the service life and explosion-proof safety of the equipment. The standard process includes the following key steps:

1. Determine the Service Factor (f ₛ)

The service factor is a comprehensive measure of load fluctuations, startup frequency, and daily running time. The determination basis is as follows:

Acceleration coefficient K: K=J-c/Jm (load inertia/motor inertia). The larger the K value, the heavier the impact.

Select the load type based on the K value:

K1: Uniform load (such as light load on conveyor belt)

K2: Medium impact load (such as agitator)

K3: Heavy impact loads (such as crushers and elevators)

By combining the number of starts per hour (Z ₕ) and daily operating hours, refer to the f ₛ curve in the manual to obtain the service coefficient. For situations involving personal safety (such as promotion), the choice of f ₛ should be particularly conservative.