GB/T 3836.29-2021Explosive atmospheres - Part 29: Non-electrical equipment for explosive atmospheres - Constructional safety 'c', control of ignition source 'b', liquid immersion 'k' (English PDF)

5.1 General requirements

Equipment designed and constructed according to the applicable safety requirements of the relevant industrial standards is intended to be capable of functioning in conformity with the operational parameters established by the manufacturer, including any mechanical and thermal stresses that they are intended to be subjected to.

5.2 Ingress protection

5.3 Seals for moving parts

5.3.1 Unlubricated gaskets, seals, sleeves, bellows and diaphragms

Un-lubricated gaskets, seals, sleeves, bellows and diaphragms shall not become an effective ignition source, e.g., if there is a risk of mechanically generated sparks and hot surfaces which can become an effective ignition source. Light metals shall not be used for these parts in this case (see GB/T 3836.28-2021).

5.5 Vibration

Effective ignition sources, hot surfaces or mechanically generated sparks or loss of protection, caused by vibration shall be avoided. Vibration can arise from the equipment itself or from the place where it is mounted.

5.6 Requirements for moving parts

5.7 Requirements for bearings

5.7.1 General

Bearings are basically divided into three types, sliding plane motion, sliding rotary motion and rolling element. When assessing bearings, as part of the ignition hazard assessment required by GB/T 3836.28-2021, at least the following shall be considered.

5.7.3 Chemical compatibility

5.8 Requirements for power transmission systems

5.8.1 Gear drives

Gear drives shall comply with the requirements in 5.1.Where the ignition hazard assessment (see GB/T 3836.28-2021) shows there could still be an ignition source, another form of ignition protection shall be used (e.g., protection by liquid immersion, see Clause 7).

Where equipment includes facilities to change the gear ratios (manually, or automatically), the gear changing mechanisms shall be so arranged as to ensure that they are incapable of producing either temperatures exceeding the maximum surface temperature or incendive mechanically generated sparks.

5.8.2 Belt drives

6.1 General

For application of Type of Protection “b”, control systems are required that are.

6.2 Determination of the control parameters

6.2.1 General

Where the ignition hazard assessment described in GB/T 3836.28-2021 has revealed potential ignition sources and the manufacturer has decided to reduce the likelihood of them becoming effective by the application of the protection described in Clause 6, the equipment manufacturer shall determine, by calculation or type tests, the control parameters (e.g., temperature, speed, pressure, etc.) associated with those potential ignition sources.

6.2.2 Determination of the safety critical values

Each safety critical value shall be determined by the manufacturer as that value above or below which a potential ignition source may become effective. The set points relevant for control of ignition sources shall be given in the instructions of the controlled equipment and shall be clearly identified as safety critical.

6.3 Ignition prevention system design and settings

6.3.1 Determining the performance requirements or operating characteristics

The manufacturer shall specify the performance requirements or operating characteristics (e.g., if the device is a fusible plug) of the ignition prevention systems / devices intended to be used in the equipment. Examples of the factors that should be considered are.

6.3.2 Instructions

The performance characteristics of the ignition prevention system specified by the manufacturer shall be included in the instructions.

7.1 Determination of the maximum / minimum criteria

The manufacturer of the equipment shall determine by calculation and / or by type testing the following maximum / minimum criteria.

7.2 Protective liquid

The protective liquid used shall be of such viscosity and chemical composition that it.

7.3 Equipment construction

7.3.5 Level monitoring

Monitoring device(s), indicator(s), or gauge(s) shall be so designed and constructed that they indicate the actual level.

7.3.6 Loss of liquid

Where there is the possibility of the protective liquid being lost e.g., by evaporation, capillary or siphon action, the loss shall be avoided or means provided to replenish the liquid.

8.1 Type tests for equipment with Type of Protection constructional safety

“c” See GB/T 3836.28-2021.

8.2 Type tests for equipment with Type of Protection control of ignition

source “b”

8.3 Type tests for equipment with Type of Protection liquid immersion “k”

8.3.1 General

When tested in accordance with 8.3.2 or 8.3.3, no loss of liquid shall occur to the equipment, which would cause the liquid level to fall below the minimum criteria determined in Clause 5.The following tests shall be performed without the equipment operating.

The pressure test is not required for the enclosure in the case of open equipment.

9.1 Documentation for equipment with Type of Protection constructional

safety “c”

9.2 Documentation for equipment with Type of Protection control of

ignition sources “b”

9.3 Documentation for equipment with Type of Protection liquid

immersion “k”