BS EN ISO 8846-2017 pdf free download.Small craft – Electrical devices – Protection against ignition of surrounding flammable gases (ISO 8846:1990)
This International Standard describes test methods and requirements for the design of electrical devices to be used on small craft so that they may be operated in an explosive atmosphere without igniting surrounding flammable gases. It does not require explosion-proof or explosion-protected electrical apparatus as defined in IEC 79-0. [1]
This International Standard does not cover ignition protection procedures for products or components that may operate in hydrogen and air mixtures. Nor does it cover mechanisms of ignition from external sources, such as static electricity, lightning or other factors not related to the apparatus under test.
2 Definitions
For the purposes of this International Standard, the following definitions apply.
2.1 flammable hydrocarbon mixture Mixture of propane and air (per cent by volume) between the Lower Explosive Limit (LEL) and Upper Explosive Limit (UEL) that will explode if ignited by any means. Tests using propane and air are considered to cover marine fuel and air mixtures between the LEL and UEL.
2.2 ignition-protected device Device that complies with the requirements of one of the test programmes given in clause 3.
2.3 ignition source (1) Any electrical contacts, commutator or brush assembly, or collector ring and brushes that may produce electrical arcs of ignition-capable energy. (2) Resistor or other component or surface that may operate at a temperature sufficient to ignite a flammable mixture.
2.4 normal operating conditions Any operating conditions of the device, including the maximum achievable overload up to 400 % of the rated current (circuit breakers, switches and the like) and a stalled rotor condition for any motor with the circuit protected by an overcurrent protective device specified by the product manufacturer.
3 Test programme
3.1 The external surface temperature test shall be carried out according to clause 4.
3.2 Electrical devices which can generate sparks or arcs under operation (switches, relays, generators, fuses, distributors, cranking motors, etc.) shall be tested according to clause 5 if they can be considered sealed and according to clause 6 if they are non-sealed.
3.3 Electrical devices showing an increase of the external surface temperature of more than 100 °C above ambient under operation shall be tested according to clause 4. Electrical devices not rated for continuous operation and wired with momentarily operated switches, such as engine-cranking motors,propulsion unit trim motors and other intermittently operated devices, are exempt from this test.
4 External surface temperature test
4.1 The electrical device shall be placed in a closed, thermally insulated air-circulating oven having an initial temperature of 60 °C ± 2 °C. Suitable heating shall be provided in addition to that generated by the component in order to keep the temperature in the oven constant at 60 °C ± 2 °C.
4.2 The test voltage supply shall be adjusted within the range of 80 % to 120 % of the nominal system voltage giving the greatest temperature increase.
4.3 The electrical device shall be operated continuously for a minimum of 7 h in the mode in which it draws its maximum current.
4.4 The maximum allowable surface temperature is 200 °C, measured at any point on the electrical device exterior.
5 Test method — Sealed devices
Electrical devices which under operation can produce sparks or arcs shall be tested according to 5.1 and 5.2 if they are considered so tight that no surrounding gases can penetrate into them.
5.1 Equipment
A water chamber, as shown in figure 1, is needed.
5.2 Test procedure
5.2.1 Submerge the electrical device to be tested in a water chamber at ambient temperature, changing its attitude if necessary so that all possible sources of leaks are at the top and are 340 mm to 370 mm below the water surface. Submerged time is 15 min for each attitude change.
5.2.2 Observe the electrical device under test carefully throughout the test duration for a leak as evidenced by the generation of a bubble or stream of bubbles.
5.2.3 If bubbles are observed coming out of the electrical portion of the device, the electrical device shall not be considered sealed and shall be tested under clause 6.
5.2.4 If no bubbles are observed, remove the electrical device from the water chamber and dry its exterior.
5.2.5 Dismantle the electrical device for internal inspection.
5.2.6 If no water is found inside the electrical device, it shall be accepted as a sealed ignitionprotected device. If water is found, it shall be tested according to clause 6.
6 Test method — Non-sealed devices
Testing according to 6.1 to 6.4 shall be carried out on electrical devices which under operation can produce sparks or arcs and are considered to be open so that surrounding gases can penetrate into them. Electrical devices which after testing according to clause 5 have been found to be non-sealed shall also be tested as in 6.1 to 6.4.BS EN ISO 8846 pdf download