GB/T 26716-2023 Horology - Magnetic resistant watches
1 Scope
This document specifies the technical requirements for magnetic resistant watches, it provides it indicates the marking which the manufacturer is authorized to apply to them and it describes the test methods.
This document applies to design and test of magnetic resistant watches which can withstand daily magnetic fields.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
ISO 3158 Timekeeping instruments - Symbolization of control positions
Note: GB/T 4028-2013 Symbolization of control positions for timekeeping instruments (ISO 3158:1976, IDT)
3 Terms and definitions
....
....
3.1
magnetic resistant watch
watch designed to withstand a homogeneous and continuous direct current magnetic field of 4800 A/m encountered on a daily basis
3.2
enhanced magnetic resistant watch
watch designed to withstand a homogeneous and continuous strong direct current magnetic field equal or higher than 16000 A/m encountered in close proximity
3.3
residual effect
difference of rates before and after the magnetic resistance test
4 Requirements
4.1 Requirements
Magnetic resistant watches shall meet the requirements of 4.2 or 4.3 when applying magnetic fields of 4800 A/m. Enhanced magnetic resistant watches shall meet the requirements of Annex A.
4.2 Requirements for mechanical watches
4.2.1 Running conditions of mechanical watches during magnetic fields application
When observed during the magnetic fields application, watches shall not stop.
4.2.2 Residual effect for mechanical watches after magnetic fields application
The residual effects dCH－X on the watch rate are calculated as by the following formulae as differences between rates after magnetic fields application MCH-X and initial rate MCH-0.
- Residual effect with magnetic fields application in 3H-9H direction: dCH－1=MCH－1-MCH－0;
- Residual effect with magnetic fields application in 6H-12H direction: dCH－2=MCH－2-MCH－0;
- Residual effect with magnetic fields application in CH-FH direction: dCH－3=MCH－3-MCH－0.
The residual effect dCH－X shall not exceed the values in Table 1.
Foreword I
1 Scope
2 Normative references
3 Terms and definitions
4 Requirements
5 Test methods
6 Marking
Annex A (normative) Enhanced magnetic resistant watches
Annex B (informative) Flow chart for the test procedure
Annex C (informative) Relationship between strengths of magnetic fields and the distance from products generating magnetic fields
Bibliography
