GV Converter

ANSI VALVE LEAKAGE
STANDARDS

There are six different seat leakage classifications as defined by ANSI FCI 70-2. The most commonly used by Gemco Valve are CLASS I , CLASS IV and CLASS Vl

Control Valve Seat Leakage Classifications - ANSI FCI 70-2 superseding ANSI B16.104

Leakage Class Designation II

Maximum Leakage Allowable:
0.5% of rated capacity

Test Medium:
Air or water at 50-125 F (10-52C)

Test Pressure:
45-60 psig or max. operating differential whichever is lower.

Testing Procedures Required for Establishing Rating:
Pressure applied to valve inlet with outlet open to atmosphere or connected to a low head loss measuring device full normal closing thrust provided by actuator.

Leakage Class Designation III

Maximum Leakage Allowable:
0.1% of rated capacity

Test Medium:
Air or water at 50-125 F (10-52C)

Test Pressure:
45-60 psig or max. operating differential whichever is lower.

Testing Procedures Required for Establishing Rating:
Pressure applied to valve inlet with outlet open to atmosphere or connected to a low head loss measuring device full normal closing thrust provided by actuator.

Leakage Class Designation IV
also known as metal to metal. It is the kind of leakage rate you can expect from a valve with a metal shut-off disc and metal seat.

Maximum Leakage Allowable:
0.01% of rated capacity

Test Medium:
Air or water at 50-125 F (10-52C)

Test Pressure:
45-60 psig or max. operating differential whichever is lower.

Testing Procedures Required for Establishing Rating:
Pressure applied to valve inlet with outlet open to atmosphere or connected to a low head loss measuring device full normal closing thrust provided by actuator.

Leakage Class Designation V

Maximum Leakage Allowable:
0.0005 ml per minute of water per inch of port diameter per psi differential

Test Medium:
Water at 50 to 125F (10 to52C)

Test Pressure:
Max service pressure drop across valve plug, not to exceed ANSI body rating.

Testing Procedures Required for Establishing Rating:
Pressure applied to valve inlet after filling entire body cavity and connected piping with water and stroking valve plug closed. Use net specified max actuator thrust, but no more, even if available during test. Allow time for leakage flow to stabilize.

Leakage Class Designation VI
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.

Maximum Leakage Allowable:
Not to exceed amounts shown in the table below based on port diameter.

Test Medium:
Air or nitrogen at 50 to 125F (10 to 52C)

Test Pressure:
50 psig or max rated differential pressure across valve plug whichever is lower.

Testing Procedures Required for Establishing Rating:
Actuator should be adjusted to operating conditions specified with full normal closing thrust applied to valve plug seat. Allow time for leakage flow to stabilize and use suitable measuring device.

Control Valve Seat Leakage Classifications

*Bubbles per minute as tabulated are a suggested alternative based on a suitable calibrated measuring device, in this case a 0.25-inch OD X 0.032-inch wall tube submerged in water to a depth of from 1/8 to 1/4 inch. The tube end shall be cut square and smooth with no chamfers or burrs. The tube axis shall be perpendicular to the surface of the water. Other measuring devices may be constructed and the number of bubbles per minute may differ from those shown as long as they correctly indicate the flow in milliliters per minute.