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GB/T 33435-2025Small craft - Carbon monoxide (CO) detection systems and alarms (English PDF)

小艇一氧化碳（CO）探测系统及报警

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Issued by

State Administration for Market Regulation, China National Standardization Administration

Level / Type

National · Recommended

Issue date

June 30, 2025

Implementation date

October 1, 2025

Scope

GB/T 33435-2025 is the English-translated version of 小艇一氧化碳（CO）探测系统及报警.

GB/T 33435-2025 covers the carbon monoxide detectors and alarms fitted in the enclosed living spaces of small craft, and how they are designed, built and installed.

It defines which spaces count, accommodation, a galley with a drain and a toilet compartment, and leaves out canvas-covered open cockpits.

The requirements take in the alarm, including the new warning for a low battery, the temperature range the detector must work over, where it may be mounted, the separate rules for units without their own battery, and the marking that says when a unit needs replacing; Figure 1 relates the concentration in air, with a 30 mg/kg reference line, to the carboxyhaemoglobin it produces in the blood.

Boatbuilders and equipment makers use it. Identical to ISO 12133:2021, it replaces GB/T 33435-2016, was issued on 30 June 2025 and applies from 1 October 2025.

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Document preview — GB/T 33435-2025

National Standard of the People's Republic of China

ICS: 47.080
Classification: U 37

Issued by: State Administration for Market Regulation, China National Standardization Administration

Foreword
1 Scope
2 Normative references
3 Terms and Definitions

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

This document replaces GB/T 33435-2016 "Small craft carbon monoxide (CO) detection system" and is different from GB/T 33435-2016 except In addition to structural adjustments and editorial changes, the main technical changes are as follows.

--- Changed the definition (see Chapter 3, Chapter 3 of the 2016 edition);

--- Added the requirement for alarm when the battery is low (see 5.1.5);

--- Increased the operating temperature range requirements of the detector (see 5.2.3);

--- Changed the requirements for the installation location (see 5.3.2, 5.3.2 of the 2016 edition);

--- Changed the installation requirements for carbon monoxide detectors without self-contained batteries (see 5.3.3, 5.3.3 of the 2016 edition);

--- Added requirements for replacement of markings (see 6.3);

--- Changed the reference line of 30 mg/kg in Figure 1 (see Figure 1, Figure 1 of the 2016 edition).

This document is equivalent to ISO 12133-2021 "Small craft carbon monoxide (CO) detection systems and alarms".

1 Scope

This document specifies the design, construction and installation requirements for carbon monoxide (CO) detection systems and alarms for small craft.

Appendix A to this document provides information on carbon monoxide relevant to boat and small craft navigation.

2 Normative references

The contents of the following documents constitute the essential clauses of this document through normative references in this document.

For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to This document.

GB/T 18814-2024 Small craft electrical systems - AC and DC installations (ISO 13297:2020, IDT) sures(IPCode)]

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1 Carbon monoxide

A gaseous compound consisting of one carbon molecule and one oxygen molecule.

Note: In chemical formulas, C represents carbon and O represents oxygen. In this document, the concentration of carbon monoxide is expressed as the mass fraction of CO in air.

3.2 Carboxyhemoglobin

Carbon monoxide (3.1) combines with hemoglobin to form a stable compound.

3.3 The proportion of carboxyhemoglobin

%COHb The degree to which the oxygen-carrying capacity of the blood is impaired due to the binding of carbon monoxide (3.1) to hemoglobin, expressed as a percentage.

3.4 Continuous spaces surrounded by permanent structures, including

a) designated accommodation;

b) a galley area with a drain;

c) A compartment with toilet and sewage.

Note: Cabins with or without canvas covers used for store supplies and as open passenger cabins are not considered to be enclosed accommodation spaces.

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 27 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 18814-2024Small craft - Electrical systems - Alternating and direct current installations

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