1900 Standard Series - Allied Valve Inc

Scope of Design (Contd.)1900 Soft Seat (DA) Option - How the Double Seal WorksTwo unique features distinguish the Consolidated O-Ring seatseal safety valve from other designs. These are the 45° metalto-metalload bearing seats and the slotted O-Ring retainer.Double SealThree Essentials to a Tighterand More Secure Seal:45°1) Concentric AlignmentThe nozzle bore and O-Ring retainer are both machined to anangle of 45°. This ensures that as the valve disc opens andcloses, the O-Ring is aligned concentrically against the lip ofthe nozzle. Close tolerance between the nozzle and the body,or the body and the disc guide and disc holder, also help toensure a tight seal when the valve is closed. Accuratealignment coupled with the load bearing function of the O-Ringretainer virtually eliminates O-Ring abrasion from valve action.2) Maximum Sealing ForceOn the back side of the O-Ring retainer there are two smallslots. When the valve is closed, process media enters betweenthe machined seat of the nozzle and the O-Ring retainer andproceeds up the slots behind the O-Ring. This pressure forcesthe O-Ring against the lip of the nozzle and the curved recessof the disc holder. As the pressure within the valve rises to setpoint, the O-Ring is pressed tightly against the nozzle tomaintain maximum sealing force until break-away pressure isreached.3) O-Ring RetentionWhen the valve opens, the pressure behind the O-Ringescapes from the same two slots on the O-Ring retainer. Thisprevents the O-Ring from being ejected. Additionally, theO-Ring encapsulating retainer prevents the O-Ring from beingpulled from its setting by the high velocity, low pressuredischarge inside the upper valve body.1900 Series Safety Relief Valve | 1900.19