Standards Development

Scope

This document specifies the technical requirements and the necessary tests of excess flow valves for use with SCBAs up to 300 bar operating pressure according to EN 137 without and with a second medium pressure connection according to Annex A.

Exhaust devices that interact mechanically with the valve or lower-spindle of the valve and only close the flow in the event of a valve break-off do not fall within the scope of this document.

Requirements of EN 137 apply without restrictions

Purpose

Breathing air cylinders often fly around uncontrollably. If a person is hit by an air cylinder, the consequences can be serious.

The cause of uncontrolled flying is either a broken valve or an inadvertently opened handwheel.

If highly compressed air suddenly escapes from the cylinder, the recoil will turn the cylinder into a projectile.

The valves on breathing air cylinders are robust. However, if they receive a blow, they can break or be damaged to such an extent that they can break at the next opportunity, even if only a small amount of force is applied.

It cannot always be ruled out that a cylinder will fall. There have also been cases where the cylinder has rotated on the floor due to an accidental turn of the handwheel and the valve has been knocked off when it hits an obstacle.

If the cylinder valve is dropped or subjected to any other force, this must be reported immediately and the cylinder and valve must be subjected to an extraordinary inspection.

The new standard is intended to give design and testing requirements for excess flow valves which can be and are already used to reduce the gas flow of a compressed air cylinder in case of a broken cylinder valve or an inadvertently opened handwheel. Until now, the labelling of excess flow valves was manufacturer-specific and therefore different, which is to be remedied by this standard.