0 5 leakage of full open valve capacity.
Metal seated ball valve leakage class.
Identical to class ii iii and iv in construction and design intent but no actual shop test is made.
Class vl is known as a soft seat classification.
Intended for double port or balanced singe port valves with a metal piston ring seal and metal to metal seats.
Class iv is also known as metal to metal.
Count on class iv or pick a different design.
Class ii valve leakage classifications.
Ansi class iv shutoff is the industry standard.
Is also know as dust tight and can refer to metal or resilient seated valves.
You might get better than class iv shutoff from a metal seated ball valve for a few cycles but not over the long term in our experience.
Control valve seat leakage establishes a series of six seat leakage classes for control valves and defines the test procedures.
C leakage rates d possibly will apply for metal seated check valves.
It is the kind of leakage rate you can expect from a valve with a metal shut off disc and metal seat.
A leakage rate a is intended to apply for soft seat e g elastomeric or polymeric valve closure elements.
Metal seated ball valves are rarely bidirectional sealing but they do tend to have floating rather than trunnion mounted balls.
In fact even for metal seat valves the api 598 leak acceptance criteria for metal seated valves excluding check valves allows less leakage than fci 70 2 isa s75 19 class vi en60534 4.
The ansi standard fci 70 2.
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Class vl is known as a soft seat classification.
Soft seat valves are those where the seat or shut off disc or both are made from some kind of resilient material such as teflon.
Cass i is also known as dust tight and can refer to metal or resilient seated valves.
Class i is also know as dust tight and can refer to metal or resilient seated valves.
B leakage rates b possibly will apply for metal seated valves on more critical services.
Class ii valve leakage classifications.
For zero leakage metal seated valves api 6d iso 5208 rate a or api 598 soft seated zero leakage criteria can be specified such as triple offset metal.
It is the kind of leakage rate you can expect from a valve with a metal shut off disc and metal seat.
Class iv is also known as metal to metal.
Ansi class v the ansi class v shutoff is defined as 0 0005 cm2 min per inch of orifice diameter per pound per square inch psi.
