- Branche: Industrial valves
- Number of terms: 3113
- Number of blossaries: 0
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The bonnet or bonnet assembly is that portion of the valve pressure retaining boundary which may guide the stem and contains the packing box and stem seal. The bonnet may be integral to the valve body or bolted or screwed. The bonnet, if it is detachable, will generally provide the opening to the valve body cavity for removal and replacement of the internal trim. The bonnet is generally the means by which the actuator is connected to the valve body.
Industry:Industrial valves
The chamber located in the bonnet which surrounds the stem and contains the packing and other stem-sealing components.
Industry:Industrial valves
The body of the valve is the main pressure boundary. It provides the pipe connecting ends and the fluid flow passageway. It can also support the seating surface and the valve closure member.
Industry:Industrial valves
This type of valve is very economical from a manufacturing and stocking standpoint because a valve that is rated as a 600# ANSI valve can also be used between 150# and 300# ANSI flanges thus eliminating the need to manufacture three different valve bodies or stock three different valve bodies. The down side is that valves with flangeless bodies are not acceptable in certain applications – particularly in refinery processes.
Industry:Industrial valves
Or normally closed. Another way of describing an air-to-open actuator. Approximately 80% of all spring return diaphragm operators in the field are of this construction.
Industry:Industrial valves
Or normally open. Another way of describing an air-to-close actuator.
Industry:Industrial valves
It is the relationship between valve capacity and valve travel and is usually expressed graphically. It is derived from testing a valve with water as the fluid and with a constant pressure drop across the valve. The most common types of inherent flow characteristics are linear, equal percentage, modified parabolic, and quick opening.
Industry:Industrial valves
Is an undersized orifice. Reduced or restricted capacity trim is used for several reasons. (1) It adapts a valve large enough to handle increased future flow requirement with trim capacity properly sized for present needs. (2) A valve with adequate structural strength can be selected and still retain reasonable travel vs. Capacity relationships. (3) A valve with a large body using restricted trim can be used to reduce inlet and outlet fluid velocities. (4) It can eliminate the need for pipe reducers. (5) Errors in over sizing can be corrected by use of restricted capacity trim.
Industry:Industrial valves
Occurs only in liquid service. In its simplest terms cavitation is the two-stage process of vaporization and condensation of a liquid. Vaporization is simply the boiling of a liquid, which is also known as flashing. In a control valve this vaporization takes place because the pressure of the liquid is lowered, instead of the more common occurrence where the temperature is raised. As fluid passes through a valve just downstream of the orifice area, there is an increase in velocity or kinetic energy that is accompanied by a substantial decrease in pressure or potential energy. This occurs in an area called the vena contracta. If the pressure in this area falls below that of the vapor pressure of the flowing fluid, vaporization (boiling) occurs. Vapor bubbles then continue downstream where the velocity of the fluid begins to slow and the pressure in the fluid recovers. The vapor bubbles then collapse or implode. Cavitation can cause a Choked Flow condition to occur and can cause mechanical damage to valves and piping.
Industry:Industrial valves
