Sizing of latex neck seals used with diving equipment
Health and Safety Executive - Safety alert
Hazardous Installations Directorate - Energy Division 4.7 (Diving)
27 November 2013
Latex neck seals used in the diving industry need to be correctly fitted to the diver. A neck seal that is too large allows water ingress or gas escape and a neck seal that is too small can cause severe breathing problems leading to unconsciousness and if not acted on quickly, death. Diving contractors, supervisors and divers must ensure that neck seals are correctly sized for the individual diver.
Latex neck seals are commonly used on drysuits and a range of diving helmets to provide a watertight seal around the neck. It is very important that these neck seals are the correct size for the diver's neck. In particular a neck seal that is too tight can restrict blood vessels and affect nerve function in the neck, resulting in unconsciousness and if not acted on quickly, death.
Latex neck seals are supplied in a range of sizes which can then be trimmed for a comfortable yet waterproof fit. Some neck seals are marked around their inner circumference in order to help even trimming. It is most important that the right size neck seal is initially selected and then trimmed as required for a comfortable fit.
The wide use of neoprene seals in the diving industry can result in a diver progressing through training and well in to a diving career without using a latex neck seal. The assumption that all divers have been trained and are experienced in the use of latex neck seals is therefore not correct. Although it is a simple and basic procedure, the potential outcome of getting it wrong is grave. It is not safe to assume that all divers realise the need to correctly size and, when required, trim the neck seal or that all divers understand the possible consequences of not doing so.
Diving Contractors, Supervisors and divers need to be aware of the potentially fatal consequences of wearing an over-tight neck seal and ensure that the neck seal being worn is a comfortable fit prior to commencing a dive, or spending time wearing a neck seal (eg standby diver). Dive supervisors are to ensure that their divers understand and implement the correct procedures with regard to fitting latex neck seals.
Relevant legal documents:
With respect to the fitting of neck seals with the Kirby Morgan SuperLite® 17C Helmet, see the manufacturers guide: Kirby Morgan SuperLite® 17C Helmet Operations and Maintenance (Page 27)
For further information contact:
Health and Safety Executive
Hazardous Installations Directorate
Energy Division Unit 4 - Section 7
Lord Cullen House
Aberdeen AB25 3UB
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