Tech diving specialist Halcyon has issued a mandatory safety inspection and service campaign for all oxygen MAV regulators used with its Symbios closed circuit rebreather (CCR).
Owners of a Symbios rebreather system should not use it until the inspection and service have been conducted.
A MAV – or Manual Add Valve – is the valve a CCR diver uses to manually inject gas into the breathing loop rather than relying on the unit’s automatic oxygen-control system.
The valve operates in a similar fashion to the purge button on a conventional second stage regulator, delivering gas from a first stage regulator connected to a tank of high-pressure oxygen.
Halycon says some Symbios-specific oxygen MAV regulators may not be oxygen-clean due to particles or residue remaining from the manufacturing process.
All equipment used for high-pressure oxygen must use oxygen-compatible parts and undergo a thorough oxygen cleaning process to prevent contaminants from igniting, which could lead to an uncontrollable fire known as a deflagration.
A statement posted on the company’s Facebook page says:
Halcyon has received reports of oxygen-fire events involving the oxygen-service MAV regulator assemblies used with the Symbios rebreather system.
Halcyon has determined that some regulators may contain particles or manufacturing residue, increasing the risk of an oxygen fire.
Additional inspection and service measures related to the MAV regulator assembly are required to further enhance safety and ensure continued compliance with Halcyon’s oxygen-service standards.
Corrective action
In order to correct the problem and prevent any safety issues, Halcyon has offered to inspect and service affected oxygen MAV regulators at no cost to the diver.
Symbios owners are advised to contact their nearest official service agent, who will:
- Inspect and verify oxygen-service cleanliness standards
- Perform any required cleaning or corrective maintenance
- Install a flow restrictor in the oxygen pressure-sensor supply circuit
- Verify proper assembly and operational performance before returning the unit to service.
Halcyon notes that the MAV regulator design successfully completed oxygen-compatibility testing, and a flow restrictor was added ‘to provide an additional margin of safety and further reduce the potential consequences of an oxygen-system ignition event.’
The oxygen restrictor will be added to units during the inspection and services, if they are not already configured.
Enhanced manufacturing controls
In response to this event, Halcyon says it has implemented enhanced inspection, assembly, cleaning, and quality-verification procedures, including in-house cleaning, assembly, and 100 per cent inspection of MAV regulators used in current and future productions.
Affected Symbios rebreather owners should contact Halcyon at 𝐭𝐞𝐜𝐡𝐬𝐞𝐫𝐯𝐢𝐜𝐞𝐬@𝐡𝐚𝐥𝐜𝐲𝐨𝐧.𝐧𝐞𝐭 for further information.
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