Foreword

This European Standard has been prepared by Technical Committee CEN/TC 136 „Sports, playground and other recreational equipment", the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January 1998, and conflicting national standards shall be withdrawn at the latest by January 1998.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republik, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.

Introduction

A snorkel allows the user to breathe, when faced downward, without having to raise the mouth out of the water. However, using a snorkel complicates the breathing process.

At normal breathing conditions, a certain amount of residual air remains in the bronchial tubes and trachea, referred to as the natural dead space. When using a snorkel, an artificial dead space is added, thus increasing the total dead space. This, in turn, decreases the fraction of the inhaled air volume participating in the respiratory exchanges.

Moreover, the submerged length of the snorkel shifts the static balance of the respiratory system. Lastly, dependent on the snorkel's dimensions and shape the breathing resistance increases.

This standard deals with these problems in terms of setting constructional as well performance requirements. Accordingly, corresponding test methods are assigned.

The protection offered by a snorkel cannot guarantee the absence of accidents of fatal outcome or leading to long term disability. For this reason, due care should always be exercised when using a snorkel.