GB/T 39488-2020Safety and control devices for gas burners and gas-burning appliances - Particular requirements - Electronic type gas and air ratio control system (English PDF)

3.1 electronic type gas and air ratio control system

ERC A closed-loop control system composed of an electronic control module, actuators (including at least a gas regulating unit and an air flow regulating unit), and specified feedback signals, used to regulate the gas and air ratio. See Figure 1.

3.2 electronic control module

An electronic main control module containing all input/output control elements. See Figure 1.

3.3 defined state

A safe state that the system enters after a fault, characterized by one of the following.

a) The system passively enters a state where the gas supply is cut off, and when the cause of entering this state no longer exists, restarting is only possible in accordance with specific requirements;

b) The system actively executes a safety shut-down or enters a locked state within a specified time;

c) The system continues to operate and meets all safety-related functional requirements.

NOTE. adapted from GB/T 30597-2014, Definition 3.15.

3.4 fault reaction time

The time from the occurrence of a fault to the ERC entering the defined state.

NOTE. adapted from GB/T 30597-2014, Definition 3.16.

3.5 safety shut-down

Achieving safe gas shut-off through a limiter, safety shut-off device or internal fault detection.

NOTE. adapted from GB/T 14536.6-2008, Definition 2.3.122.

4.1 General Requirements

The ERC shall be a closed-loop system and shall comply with the following provisions.

a) The ERC shall include at least an electronic control module, two actuators (gas and air regulating unit part), and a sensor part (gas and air regulating unit sensor part or process sensor part). The structure and acceptable feedback types are shown in Figure

1 and Table 1;

Figure 1 -- Schematic Diagram of ERC Structure

b) The entire system shall include external devices, such as servo motors, regulators, positioning devices, sensors, variable speed controllers for the combustion air blower, and combustion analysis feedback systems, etc.;

c) The ERC shall have continuous related self-test modes, such as operating mode,

4.3 Materials

The materials of the regulator and related mechanical components shall comply with the requirements of 5.3 in GB/T 30597-2014.

4.4 Gas Connection

The connection mode of the gas regulator and related mechanical components shall comply with the provisions of 5.4 in GB/T 30597-2014.

4.5 Electronic Elements

The structural design of the part of ERC that uses electronic elements shall comply with the provisions of 5.5 in GB/T 30597-2014.

5.1 General Requirements

The ERC shall comply with the provisions of 6.1 in GB/T 30597-2014.

5.2 Component Requirements

The components of the regulator shall comply with the provisions of 6.2 in GB/T 30597-2014.

5.3 Performance Requirements

5.3.1 Airtightness

The airtightness of the gas regulator of the ERC shall comply with the provisions of 6.3.1 in

GB/T 30597-2014.

5.3.2 Torsion and bending

The torsional and bending resistance of the regulator of the ERC shall comply with the provisions of 6.3.2 in GB/T 30597-2014.

5.3.3 Rated flow rate

The rated flow rate of the ERC regulator shall comply with the requirements of 6.3.3 in GB/T 30597-2014.

5.3.4 Durability

The durability of the ERC regulator and related mechanical components shall comply with the requirements of 6.3.4 in GB/T 30597-2014.

5.3.5 Functional requirements for electronic control module

5.3.5.1 General requirements

5.3.5.1.1 The ERC shall be assessed as a complete closed-loop system. Its feedback signal shall

ensure that it can meet and comply with preset control value requirements to prevent dangerous situations.

5.3.5.1.2 When single-position feedback potentiometers (single potentiometers) are used for

position feedback in the electromechanical regulator, except for dedicated potentiometers that are part of the ERC and whose integrity can be checked by a certain method (for example, fault detection within 3 seconds), other single-position feedback potentiometers shall comply with the provisions of Appendix D.

5.3.5.1.3 The ERC shall be interconnected and locked with the burner control system, and such

interconnection and locking shall not reduce the safety of the entire system.

5.3.5.1.4 When the ERC operates for longer than the manufacturer’s declared value outside of

a pre-set or pre-determined range, it shall be in a defined state.

5.3.5.1.5 In the presence of internal faults or foreseeable unspecified operating conditions, the

ERC shall be in a defined state.

5.3.5.2 Restart or locking after safety shut-down

5.3.5.2.1 When restarting after a safety shut-down, the number of restarts and the time intervals

shall comply with the provisions of the corresponding overall machine standard.

5.3.5.2.2 When designing the program, safety shut-down conditions shall be designed first, followed by automatic restart conditions.

5.3.5.2.3 When locking after a safety shut-down, the type of locking shall comply with the

provisions of the relevant overall machine standard.

5.3.5.3 Start-up sequence

The burner control system shall provide control commands for the start-up sequence to the ERC, and when a fault occurs, the ERC shall be in a defined state.

5.3.5.4 Accuracy

The manufacturer shall declare the accuracy of the ERC and shall provide at least the following information.

a) The closed-loop method used in the ERC (sensor, regulator and electronic control module), see 4.1;

b) Relevant parameters of the sensor and regulator as specified in Appendix E, see Table E.1 and Table E.2;