These rates are regulatory limits on the amount of fluid or gas that can escape from equipment, systems, or processes over a specific period. Types of valve leakage, valve leakage class, acceptable rates of control valve seat leakage, seat leakage test procedures and comparison of international standards There are 10 leakage rates specified in iso 5208
Maximizing Valve Performance with Known Leakage Rates: The Key to Success in Pneumatic Applications
A, aa, a, b, c, cc, d, e, ee, f, g and the rate a is the highest grades
Iso 5208 maximum allowable closure test leakage rate
Note 2 the leakage rates only apply when discharging test fluid to the atmosphere. The maximum permissible leakage rate shall be 0.18 cubic inch (3 cubic centimeters) per minute per inch of nominal pipe size The maximum permissible leakage rates shall be 1.5 standard cubic feet (0.042 cubic meter) of gas per hour per inch of nominal pipe size The following table is for the allowable closure leak value testing with water at 1.1 times rated pressure and gas at low pressure (about 80 psig) or high pressure if specified by customer
For check valve allowable leakage rate, please see api 598 check valve allowable leakage rate. Valve leakage class is a standardized rating that defines the maximum allowable internal leakage through a valve when it's fully closed These ratings range from class i (least strict) to class vi (most stringent). The most commonly used by gemco valve are class i, class iv and class vl
Class i is also know as dust tight and can refer to metal or resilient seated valves
Class iv is also known as metal to metal Before performing a duct leakage test, you must know the allowable leakage for the duct system you are testing Usually, the limit will be expressed as a percentage of total system volume flow, or it will have to be calculated from a specified leakage class Knowing the allowable leakage and the test pressure will allow […]
