The control valves are mainly for throttle with some minimal locked-up capacity. The ability to shut off the mouth of a valve depends on factors like whether using an unbalanced or balanced plug, thrust on an actuator, the material of the seat, and the type of fluid. All these play a vital role in determining how the valve shuts off. There are different valve categories based on the extent of leakage permissible.
Types of Valve Classification Based on Leakage
According to the ANSI standard, valve leakage results in the classification of types of valves. It defines a different test procedure and the extent of leakage in each valve-based system.
- The first category is dust-tight, and the seated valves are metal resistant
- The second category allows maximum leakage, and it is seen mostly in commercial valves or single-seat valves that come with ring seals or metal seats. The permissible leakage extent is decided depending on the seal material and the valve
- It also offers a high permissible leakage option but a higher degree of seal tightness. The seal is a quality one than that of the second category
- It gives maximum leakage to commercial single-seat control valves with piston rings and metal seats
- For critical applications, valves need to be closed with differential pressure on the seating surface. It goes through special manufacturing tactics and testing methods to ensure it is perfect for use.
- This again offers maximum leakage with a resistant leakage valve and an unbalanced or unbalanced seat with “O” rings
What are the Reasons for Valve Leakage?
The common cause of valve leakage is as follows:
- Valve seats prevent from closing its mouth due to dirt, rust or debris
- The valve will not be closed fully, which also impacts the permissible leakage in the valves
- When the valve seat is damaged
- Insufficient actuator in the valve
It mainly lessens users that complain about incorrect use of leakage requirements of valves. The valve manufacturers should follow the testing norms and ensure that it has been tested using the correct parameters. If a customer wants to specify some additional restriction on the leakage rate, they need to specify it with the leakage rate. So, know the classification of types of valves in detail and order premium items from QRC Valves. It has the best options to pick from in the budget.