GB/T 40815.6-2026 Active National standards

GB/T 40815.6-2026 Mechanical structures for electrical and electronic equipment—Thermal management for cabinets in accordance with inch and metric system—Part 6:Air recirculation and bypass of indoor cabinets

Publish Date: 2026-02-27 Implement Date: 2026-09-01 For services related to genuine standard inquiry, procurement, translation, and other related services in China, please Contact Us

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Basic Information

Standard Code: GB/T 40815.6-2026

Standard Type: National standards

Standard Status: Active

is_force_gb: no

CCS Name: Mechanical structure of electrical products

ICS Name: Mechanical components for electronic devices

Publish Date: 2026-02-27

Implement Date: 2026-09-01

Pages: 28 pages

Scope

This document pertains to the thermal management of cabinets that comply with the IEC 60297 and IEC 60917 series. It provides compatible measurement methods for recirculation rate and bypass rate, which are indicators defining the quality of airflow in forced air cooling systems. These measurement methods can be universally applied to indoor cabinets equipped with plug-in boxes and/or cabinet-based equipment.
Note 1: Both recirculation and bypass represent leaked airflow, which is a harmful phenomenon in terms of cooling efficiency. These measurements are clearly aimed at mitigating such issues.
This document includes the following content:
a) Definitions of recirculation and bypass flow in cabinet cooling;
b) Grading of the recirculation rate (RC);
c) Definitions of the recirculation rate (RCs) for forced air cooling plug-in boxes and/or cabinet-based equipment installed in the cabinet;
d) Definitions of the recirculation rate (RCr) and bypass rate (BPr) for the entire cabinet;
e) Requirements for each temperature measurement method needed to calculate the recirculation rate (RCs), RCr, and bypass rate (BPr).
Note 2: This document includes provisions for measuring the bypass rate, but not for specifying its level.
The schematic diagrams used here are not intended to guide product design, but rather serve as explanatory illustrations when defining forced air cooling airflow.
The recirculation and bypass measurement methods discussed in this document assume applicability to indoor-installed cabinets. The cooling air inlet is located at the front or bottom of the cabinet, and the heated air is discharged at the rear or top. These methods are also applicable to cabinets installed outdoors and equipped with cooling devices such as heat exchangers or air conditioners at the front or rear (see Appendix C).
The recirculation rate of a plug-in box or cabinet is defined for each individ