Bonfiglioli C-series ATEX gearbox selection and explosion-proof application guide

Bonfiglioli C series ATEX explosion-proof helical gear reducer

In the field of modern industrial drive, especially in industries such as petrochemicals, powder processing, pharmaceuticals, and food processing, equipment not only needs to meet strict requirements for transmission efficiency and reliability, but also must cope with the enormous challenges of potential explosive environments. As a global leader in power transmission and drive, Bonfiglioli's C-series helical gear coaxial reducers are renowned in standard industrial settings for their compact design, high torque density, and excellent reliability. However, when these devices must be deployed in hazardous areas with flammable gases, vapors, or dust, the understanding of their technical characteristics and compliance must be elevated to a whole new level - ATEX compliance and special selection logic.

This article aims to provide a deep technical interpretation of Bonfiglioli C-series ATEX explosion-proof reducers for professional engineers and technicians. We will strictly follow the core concept of its technical manual, conducting comprehensive and refined analysis from the practical application of ATEX directive, key steps of selection calculation, to structural characteristics and installation specifications, to help you safely, compliantly, and efficiently complete equipment selection and operation.

Understand the ATEX compliant architecture of C-series explosion-proof reducers

Many engineers' understanding of ATEX is limited to the word 'explosion-proof', but a deep understanding of its classification is crucial for equipment selection. The C-series gearbox complies with the EU ATEX 2014/34/EU directive, and its core value lies in providing different levels of protection based on the explosion risk level. According to the manual, Bonfiglioli C-series products mainly cover equipment categories 2 and 3, which are represented by codes such as 2G/3G and 2D/3D.

1. Distinguishing between gas and dust

G (Gas): Suitable for potential explosive environments formed by gases, vapors, or mists.

D (Dust): Suitable for potential explosive environments where combustible dust is formed.

2. Corresponding relationship between device category and zone

This is the primary legal basis for selection. The configuration of C-series products determines their installable areas:

2G class equipment: suitable for Zone 1 (places where explosive gas environments may occasionally occur during normal operation) and Zone 2 (places where explosive gas environments are unlikely to occur during normal operation, and even if they do occur, the duration is very short).

3G devices: only applicable to Zone 2.

2D class equipment: suitable for Zone 21 (explosive dust environment may occasionally occur during normal operation).

3D equipment: suitable for Zone 22 (explosive dust environment is unlikely to occur during normal operation, and even if it does occur, the duration is very short).

Key point reminder: According to the manual, Bonfiglioli C series reducers are strictly prohibited from being installed underground in coal mines (Group I) and Group II Category 1 (Zone 0 or Zone 20) areas. This red line is the basic prerequisite for selection.

Deep selection calculation: Beyond conventional torque and power matching

In standard environments, gearbox selection usually only considers power and torque. But for ATEX applications, the selection process must be more rigorous, especially when it comes to the calculation of service factor (fs) and peak torque. The following is a five step manual based professional selection process:

Step 1: Determine the Application Service Coefficient (fs)

The service coefficient is not fixed, it depends on three variables: daily working hours, number of starts per hour (Z), and load type (K factor).

Load type K:

K1 (uniform load): such as smooth running conveyor belts, fans, etc.

K2 (moderate impact load): such as mixers, screw conveyors, etc.

K3 (heavy impact load): such as crushers, high-frequency reciprocating compressors, etc.

Special correction rule: For C122, C222, or C322 models, if the transmission ratio i>40 and the number of starts per hour Z>30, the calculated service factor needs to be multiplied by a correction factor of 1.2. This point is easily overlooked, but it is a hidden danger that leads to premature failure of the gearbox.

Step 2: Calculate the required input power

Firstly, based on the required output torque (Mr2) and output speed (n2) of the application, the required power (Pr1) of the motor shaft is calculated in reverse. The formula is as follows:

Pr one=Mr two×n two nine thousand five hundred and fifty×ηd[kW]

Pr one= 9550×η d Mr two×n two [kW]

among which,ηd For dynamic efficiency. According to the manual guidelines, for the C-series helical gear reducer, the efficiency value can refer to:

2-stage transmission (i ≈ 10): approximately 0.98

3-stage transmission (i ≈ 25): approximately 0.96

4-stage transmission (i ≈ 50): approximately 0.93

Step 3: Dual verification based on power and torque (IEC motor direct connection scheme)