Bonfiglioli VF-W Explosion proof Worm Gear Reducer: ATEX Selection and Installation Complete Guide

Bonfiglioli VF-W Explosion proof Worm Gear Reducer: ATEX Selection and Installation Complete Guide

In industrial fields such as chemical, petroleum, natural gas, and dust treatment, flammable gases, vapors, or dust are inevitably present in the production environment. In these locations classified as potentially explosive hazardous areas, any conventional electrical or mechanical equipment may become a source of ignition, causing catastrophic consequences. Therefore, selecting explosion-proof equipment that complies with the EU ATEX Directive 2014/34/EU is not only a mandatory requirement of the regulations, but also the cornerstone of safe production.

As a global leader in power transmission and control solutions, Bonfiglioli's VF-W series worm gear reducers are renowned in many industrial fields for their compact design, efficient transmission performance, and excellent reliability. When this series of products is combined with ATEX explosion-proof technology, the Bonfiglioli VF-W ATEX series explosion-proof worm gear reducer is born - providing an ideal safe transmission solution for applications in hazardous areas.

Understand ATEX directive and VF-W series explosion-proof rating

Before choosing an explosion-proof gearbox, it is necessary to first understand the classification of explosive environments it is suitable for. According to the ATEX directive, hazardous areas are divided into different "zones" based on the frequency and duration of explosive environments.

Gas environment (G): Zone 0 (persistent), Zone 1 (may occur during normal operation), Zone 2 (unlikely to occur, or only exists briefly).

Dust environment (D): Zone 20 (persistent), Zone 21 (may occur during normal operation), Zone 22 (unlikely to occur, or only exists briefly).

The Bonfiglioli VF-W series ATEX gearbox is mainly designed for Zone 1, 21, 2, and 22 areas, covering the vast majority of industrial application scenarios. The product category and protection level are clearly indicated on the equipment nameplate, for example:

2G/3G class (gas): suitable for Zone 1 and Zone 2. The provided temperature levels include T3 (maximum surface temperature of 200 ° C) and T4 (maximum surface temperature of 135 ° C). T4 level represents higher safety and allows equipment to be used in more hazardous gas environments.

2D/3D category (dust): suitable for Zone 21 and Zone 22. The surface temperature level can be selected as ≤ 130 ° C or ≤ 160 ° C, depending on the minimum ignition temperature of the dust on site.

Note: Bonfiglioli explicitly states that its products are not suitable for underground coal mines (Group I) and Category 1 (Zone 0/Zone 20) areas in Group II categories. This is the primary boundary condition when selecting.

Core selection process and parameter calculation for VF-W ATEX series

The correct selection is a prerequisite for ensuring the longevity and safe operation of equipment. The selection process is not simply about matching power and speed, but a system engineering that comprehensively considers load characteristics, working conditions, and environmental factors.

Step 1: Determine the application parameters and service coefficient (fs)

Firstly, it is necessary to clarify the required output torque (Mr2), output speed (n2), daily working hours, and number of starts per hour (Z) for the application. Then, the load type is determined by calculating the acceleration coefficient (K) of the load.

Definition of K coefficient: K=Jc/Jm, where Jc is the moment of inertia of the driven load converted to the motor shaft, and Jm is the moment of inertia of the motor.

K1 (Uniform Load): For example, a conveyor belt with a constant load.

K2 (medium impact load): such as mixers, small cranes.

K3 (heavy impact load): such as crushers and large elevators.

Retrieve the service factor (fs) from the chart provided in the product catalog based on the K value and the number of startups per hour.

Step 2: Calculate the selection torque (Mc2)

This is the most crucial step in selection, especially for worm gear reducers, whose efficiency is greatly affected by speed ratio and temperature.

Calculate application demand power (Pr1):

Pr1 = (Mr2 * n2) / (9550 * ηd)

Where η d is the dynamic efficiency. It is necessary to estimate the efficiency curve from the catalog based on the speed ratio (i).

Determine the calculated torque (Mc2):

For worm gear reducers (VF/W series), the formula for calculating torque is:

Mc2 = Mr2 * fs * ftp

FTP is the environmental temperature adjustment coefficient.

When the ambient temperature is ≤ 30 ° C, ftp = 1.0。

When the ambient temperature is 40 ° C, ftp=1.06 (for K2 load) or 1.17 (for K3 load).

Select gearbox model:

In the technical parameter table, find the minimum machine base size that can meet the output speed (n2) requirements and has a rated torque (Mn2) greater than or equal to the calculated torque (Mc2). Meanwhile, it is necessary to ensure that the rated input power (Pn1) meets the application requirements.

Installation specifications: Details determine explosion-proof performance

The installation of explosion-proof equipment has more stringent requirements than ordinary equipment. Any negligence in installation may result in the loss of explosion-proof function of the equipment.