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AMMUNITION FUZES (blasting cartridge initiators F42B 3/10; chemical aspects C06C); ARMING OR SAFETY MEANS THEREFOR (filling fuzes F42B 33/02; fitting or extracting primers in or from fuzes F42B 33/04; containers for fuzes F42B 39/30)
Definition statement
This subclass covers:

An assembly or mechanism which incorporates safety and arming means in order that the explosion can only take place under certain conditions; this assembly or mechanism determines also the moment (instantaneous or delayed) or the manner, e.g. impact, proximity, hydrostatic pressure, of the firing.

References relevant to classification in this subclass
This subclass does not cover:

Chemical aspects of detonating or priming devices

Fuses or fuse cords, i. e. a continuous train of explosive enclosed in a usually flexible cord or cable for setting-off an explosive charge in the art of blasting

Blasting cartridge initiators

Filling fuzes

Fitting or extracting primers in or from fuzes

Containers for fuzes

Special rules of classification within this subclass

Main groups F42C 1/00-F42C 9/00 and F42C 13/00 are organised according to physical effects causing initiation of the fuze (function).

Main groups F42C 11/00, F42C 15/00 and F42C 19/00 are organised according to structural features of the fuze (structure).

Main group F42C 14/00 is organised according to the ammunition type the fuze is intended to be used for (application).

Whenever applicable documents should be classified according to all three aspects, function, structure and application.

Double fuzes or multiple fuzes in combination with time fuzes, always classify in F42C 9/14 and lower.

Impact fuzes, i.e. fuzes actuated only by ammunition impact
Definition statement
This group covers:

Fuzes wherein the impact of the fuze onto the target activates a firing pin which then triggers immediate or delayed detonation of the warhead.

Fuzes without a firing pin wherein the impact of the fuze onto the target is detected by a sensor which in turn generates an output triggering immediate or delayed detonation of the warhead.

References relevant to classification in this group
This group does not cover:

Protruding stand-off member for hollow charges

Double action percussion fuze

Special rules of classification within this group

If the electric or electronic aspects of the sensor or delay circuit are essential to the invention, the documents needs to be classified in F42C 11/00 as well.

operating at a predetermined distance from ground or target by means of a protruding member
References relevant to classification in this group
This subgroup does not cover:

Protruding stand-off member for hollow charges

Fuzes actuated by exposure to a liquid, e.g. seawater (F42C 5/00 takes precedence; time fuzes F42C 9/00)
Definition statement
This group covers:

Fuzes activated by sensors detecting liquid exposure to liquid, e.g. components swelling or disintegrating when contacted by a liquid, in practice sea, lake or river water.

References relevant to classification in this group
This group does not cover:

Protruding stand-off member for hollow charges

Informative references
Attention is drawn to the following places, which may be of interest for search:

Initiator for blasting cartridge neutralised by contact with water

Time fuzes

Fuzes actuated by exposure to a predetermined ambient fluid pressure {(Fluid-pressure-operated switches H01H 35/24)}
Definition statement
This group covers:

Fuzes that initiate if the water pressure rises above a certain level which is applicable in depth charges.

Also includes fuzes triggered when a threshold of gas pressure is reached, e.g. though a gas generating capsule or by sympathetic detonation of a nearby explosive charge.

Also includes fuzes actuated when the pressure value goes below a predefined theshold, e.g. detonation only possible at a certain altitude.

Informative references
Attention is drawn to the following places, which may be of interest for search:

Depth charges

Initiator for blasting cartridge neutralised by contact with water

Fluid-pressure-operated switches

Fuzes actuated by application of a predetermined mechanical force, e.g. tension, torsion, pressure (by ammunition impact F42C 1/00, by exposure to a predeterminded ambient fluid pressure F42C 5/00)
Definition statement
This group covers:

The fuse is actuated by application of a mechanical force, i.e. the forceful relative displacement of two components of the fuze relative to each other. Basically a mechanical switch triggering a detonation.

References relevant to classification in this group
This group does not cover:

Impact fuzes, i.e. fuzes actuated only by ammunition impact

Fuzes actuated by exposure to a predetermined ambient fluid pressure

Informative references
Attention is drawn to the following places, which may be of interest for search:

Arming of fuzes

Percussion fuzes of the double-action type, i.e. fuzes cocked and fired in a single movement, e.g. by pulling an incorporated percussion pin or hammer (percussion caps F42C 19/10)
Definition statement
This subgroup covers:

The percussion is initiated by a spring loaded percussion pin after the relative displacement of the two components of the fuze.

References relevant to classification in this group
This subgroup does not cover:

Impact fuzes

Percussion caps

Time fuzes; Combined time and percussion or pressure-actuated fuzes; Fuzes for timed self-destruction of ammunition
Definition statement
This group covers:

Non-electronic fuzes causing detonation of the ammunition after a predetermined time from the initiation of the fuze itself, i.e. the timing is not caused by an electric or electronic circuitry.

Timing can be caused by clockwork or a burning pyrotechnic unit.

References relevant to classification in this group
This group does not cover:

Electric time fuzes, the time dely being caused by electric circuitry

Electric fuzes ({in combination with other fuzes F42C 9/14}; proximity fuzes F42C 13/00; {safety or arming effected by electric means F42C 15/40; electric contact parts for fuzes F42C 19/06}; electric igniters F42C 19/12, {F42B 3/12 to F42B 3/18; optical initiators F42B 3/113})
Definition statement
This group covers:

Fuzes characterised by the electric or electronic circuitry, which is usually triggered or controlled by one of the fuze sensor mechanisms covered in F42C 1/00 to F42C 9/18 or F42C 13/00. Generation of electricity therefore.

References relevant to classification in this group
This group does not cover:

Bridge initiators

Spark initiators

Pyrotechnic delay initiators

Safety initiators resistant to premature firing by static electricity or stray currents

Proximity fuzes

Safety or arming effected by electric means

Electric contact parts for fuzes

Electric primers, the initial explosive component in the pyrotechnic or explosive train is electrically initiated

Informative references
Attention is drawn to the following places, which may be of interest for search:

Time fuzes in combination with other fuzes

Proximity fuzes; Fuzes for remote detonation {(F42C 9/148 takes precedence; constructional details F42C 19/00; mounting of antennas F42B 30/006)}
Definition statement
This group covers:

Fuzes wherein detonation is initiated after an electronic circuitry including a non-contact (e.g. electrostatic, electrodynamic, optical, field sensitive, accoustic or magnetic) proximity sensor has determined that the proximity of the target is sufficient for optimised effect of the warhead.

References relevant to classification in this group
This group does not cover:

Proximity sensor by contacting of a protruding memeber

Proximity fuzes in combination with other fuzes

Informative references
Attention is drawn to the following places, which may be of interest for search:

Mounting of antennas on projectiles

Constructional details of fuzes

{Mechanical} fuzes characterised by the ammunition class or type (F42C 1/00, {F42C 7/00, F42C 9/00, F42C 11/001}, F42C 13/00, F42C 15/00 take precedence)
Definition statement
This group covers:

This main group is organised as an application group, i.e. non electric fuzes characterised by the ammunition they are designed for.

If a fuze is characterised by a features relating to a special adaptation for the use with a particular ammunition not listed in the sub-groups, classify in main group.

References relevant to classification in this group
This group does not cover:

Impact fuzes, i.e. fuzes actuated only by ammunition impact

Proximity fuzes; Fuzes for remote detonation

Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges

Fuzes actuated by application of a predetermined mechanical force, e.g. tension, torsion, pressure

Time fuzes; Combined time and percussion or pressure-actuated fuzes; Fuzes for timed self-destruction of ammunition

Electric circuits for fuzes characterised by the ammunition class or type

Special rules of classification within this group

This main group being an application (intended use) entry, the documents should be double classified according to their structural and functional features in F42C 1/00 to F42C 9/18 or F42C 13/00.

Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges
Definition statement
This group covers:

Mechanisms or electric circuits keeping a fuze in a safe state until certain predefined conditions, usually launch and/or flight conditions, are met and causing automatic transition the fuze into the armed state as soon as all conditions are met.

wherein a carrier for an element of the pyrotechnic or explosive train is moved (F42C 15/40 takes precedence)
References relevant to classification in this group
This subgroup does not cover:

Movable blocking member in the pyrotechnic or explosive train

Safety or arming means wherein the safety or arming action is effected electrically

wherein the safety or arming action is effected by a blocking-member in the pyrotechnic or explosive train between primer and main charge (F42C 15/18, F42C 15/40 take precedence)
References relevant to classification in this group
This subgroup does not cover:

Safety or arming means wherein a carrier for an element of the pyrotechnic or explosive train is moved

Safety or arming means wherein the safety or arming action is effected electrically

Arrangements for disarming, or for rendering harmless, fuzes after arming, e.g. after launch
Informative references
Attention is drawn to the following places, which may be of interest for search:

Fuzes for the self destruction of ammunition

Fuze-setting apparatus
Definition statement
This group covers:

Apparatus for setting the fuzes of a projectile or missile. The apparatus can either be a robotic device or classical manual device for manipulating a mechanically settable fuze, or a data interface for setting electric/electronic fuzes.

Details of fuzes (except F42C 15/00)
Definition statement
This group covers:

Structural details possibly pertinent to all types of fuzes, such as the body and the caps. Further includes details of electrical components pertinent to electric fuzes only.

Includes the primers, i.e. the initial explosive component in the pyrotechnic or explosive train.

Glossary of terms
In this group, the following terms (or expressions) are used with the meaning indicated:

In patent documents the expression/word "primer"is often used with the meaning "effects the first explosive step in the sequence of explosion"

Checking fuzes; Testing fuzes
Definition statement
This group covers:

Devices and methods for checking and testing fuzes during manufacturing or just prior to launch or deployment.

This page is owned by Office of Patent Classification.
Last Modified: 10/11/2013