Valve types globe

Pressure drop through globe valves is much greater than that for gate valves. In Y-type globe valves, the stem and seat are at about 45° to the pipe instead of 90°. This reduces pressure drop but impairs ahgnment of seat and disk. 

The gauge cocks provide a backup means to determine water levels. In general, three gauge cocks (globe valve type) are vertically installed at spaced intervals, close to the visible gauge glass. 

Low-pressure steam is the source of heat for the brine entering the reactor. The temperature transmitter is an RTD-type sensor in a tantalum-shea.thed flanged thermowell. The drawing shows a steam exchanger on a pumped feed line. The brine flow control valve is globe-style and fails closed. Section 7.5.9.4 described the use of a steam eductor as the feed mechanism. This eliminates the need for the heat exchanger. The eductor itsdf can be titanium or PTFE-lined. 

Tremblay and Andrews studied the water and water-stream flow through a halfinch needle-type globe valve [45]. The valve pressure drop for water flow was correlated by calculating resistance coefficient, K. They observed that the resistance coefficient was constant and independent of Reynolds number. 

Figure 21.3 is a mechanical drawing of the cross section of a globe valve. Globe valves are often used for regulation purposes. There are two general valve types used for regulation. 

Other common valve types include the quick-opening (globe) and the butterfly. Their characteristics are more a result of accident than design. In other words, the nature of their construction is the reason for their characteristics, not vice versa. They will generally be employed regardless of, not because of, their nonlinearity. 

Valve type. What type should it be—globe, butterfly, baU, or other ... 

Fr is a control valve s Reynolds number factor, Cvs is laminar flow control valve Cv. Cv is turbulent flow Cv. Fs is laminar or streamline flow factor. Fd is valve type modifler. Fd equals 1.0 for globe control valve and ball type rotary control valve. It equals to 0.71 for butteifly type rotary control valve. 

Valve types with low K values or L/D ratios are required due to the need to minimize pressure drop losses to optimize and maintain system efficiency. Hence, standard globe-type valves, angle or in-line... 

Valve Application Technology Functional requirements and the properties of the controlled fluid determine which valve and actuator types are best for a specific apphcation. If demands are modest and no unique valve features are required, the valve-design style selection may be determined solely by cost. If so, general-purpose globe or angle valves provide exceptional value, especially in sizes less than 3-inch NFS and hence are very popular. Beyond type selection, there are many other valve specifications that must be determined properly in order to ultimately yield-improved process control. 

Mixing Valve This type of mixing device is normally a manually operated globe valve operated at 20 to 350 kPa pressure drop. Common use of this device in refinery operations is for water and crude oil mixing before a desalter and in caustic scrubbing operations. 

A type of miniature globe valve, needle valves are used in instrument systems for throttling of small volumes. They have metal to metal seats, but due to the small size, can be used for positive shut-off (Figure 15-8). Needle valves have small passageways that may plug easily and limit their use to very small flow rates. 

Valves have two main functions in a pipeline to control the amount of flow, or to stop the flow completely. There are many different types but the most commonly used are the gate valve and the globe valve. The gate valve contains a disk that slides at right angles to the flow direction. This type of valve is used primarily for on-off control of a liquid flow. Because small lateral adjustments of the disk cause e.xtreme changes in the flow cross-sectional area, this type of valve is not suitable for adjusting flow rates. 

For partially closed globe-type valves. Multiply open Lgby 3/4 open 3.25... 

STOP-CHECK VALVES (Globe and Angle Types)... 

---