page_title: Scuba manifold
section_title: Upstream manifolds
hierarchical_section_title: Scuba manifold / Construction / Upstream manifolds
caption_attribution_description: English: Detail of scuba manifold showing barrel seal o-rings and left hand thread
context_page_description: A scuba manifold is used to connect two diving cylinders containing breathing gas, providing a greater amount of gas for longer dive times or deeper dives. An isolation manifold allows the connection between the cylinders to be closed in the case of a leak from one of the cylinders or its valve or regulator, conserving the gas in the other cylinder. Diving with two or more cylinders is often associated with technical diving.
  Several configurations are used, each with its own range of applications, advantages and disadvantages.
context_section_description: Manifolds intended for use with sets where a regulator is provided for each cylinder are connected to the cylinder valves upstream of the cylinder valve seat, to a connecting port provided specifically for this purpose. Two styles of connection are available for this arrangement – face seal, and barrel seal. Face seal connections are similar to the DIN regulator connection seal, and consist of an o-ring in a groove machined into the end of the manifold tube, which is clamped against the face of the valve port by a threaded component. Face seals are simple and rugged, but rely on tight connection for a reliable seal, and do not allow any adjustment for cylinder centre distance. Barrel seals use one or two O-rings in grooves around the end of the manifold tube, which seal against the bore of the valve port. They are usually screwed into the valve port with handed thread, and locked with a lock-nut. They are generally slightly less rugged than face seal manifolds, and more vulnerable to thread damage during assembly, but allow a small amount of cylinder centre distance adjustment, and provide a reliable seal even if not completely tight.  Manifolds of this type are commonly supplied in sets comprising a manifold and compatible left and right side cylinder valves with a choice of neck thread specification. The working components for all three valves in the set are usually identical.
caption: Detail of scuba manifold showing barrel seal o-rings and left hand thread with lock nut
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