The buoyancy of a buoyant life jacket refers to the weight it can support to keep the wearer afloat. Generally speaking, the buoyancy of a life jacket should be greater than or equal to the weight of the wearer to ensure that the wearer can float on water and stay safe.
According to the information you provided, the buoyancy of the 70kg buoyancy vest is 70kg. This means that this life jacket can hold up to 70 kg of weight. If the wearer weighs more than 70 kilograms, this life jacket may not be able to completely float on water, resulting in part or all of the body being submerged in water.
Please note that other factors should be considered when wearing a life jacket, such as the size of the wearer, stability in water and the condition of the life jacket . Therefore, in real situations, these factors must betaken into account overall to determine the actual buoyancy capacity of the lifejacket. If there are specific requirements and regulations regarding buoyancy life jackets, please follow the corresponding standards and recommendations.