Round valves

T Round valve retained by a fixed holddown and a sharp-edged hole in the tray floor for all services, including fouling, slurry and corrosive applications. 

Figure 6.4 Types of valve units, (a) An uncaged, mind valve unit. (6) A caged, round valve unit, (c) A caged, round valve unit featuring contoured orifice, fd) A rectangular valve unit it) A futed, round valve unit, if) A fixed, triangular v hre unit, (forts a and e courtesy of Gtiisch Inej parts b, c and f courtesy of Koch Engineering Company, Inc. pari d courtesy of Nutter Engineering.)...

For a round valve with a diameter dv at the narrowest opening, the expressions for Af and are... 

Plug Cocks These valves (Fig. 10-152) are limited to temperatures below 260°C (500°F) since differential expansion between the plug and the body results in seizure. The size and shape of the port divide these valves into different types. In order of increasing cost they are short venturi, reduced rectangular port long venturi, reduced rec taugular port full rectangular port and full round port. 

For the larger sizes in high-pressure service, the fixed-ball type with O-ring seat seals requires less operating effort. However, these require two different plastic materi s with resistance to the fluid and its temperature. Like plug cocks, ball valves may be either restricted-port or full-port, but the ports are always round and pressure drop is low. 

We later learned that water valves with lever handles (frequently seen in hospitals or in sinks intended for disabled persons) are designed for the lever to be pushed away from the user to close the valve. Thus, the cold water valve designed for a lever will turn to the left to close. If a round handle is fitted instead of the lever. . . splash ... 

Flexitray Type A Figure 8-72 valve lift w/srp edge orifice, round Koch Higher than Sieve Tray. Lower entrain than Sieve Wide range Low Good... 

The rotary spool directional control valve. Figure 40.24, has a round core with one or more passages or recesses in it. The core is mounted within a stationary sleeve. As the core is rotated within the stationary sleeve, the passages or recesses connect or block the ports in the sleeve. The ports in the sleeve are connected to the appropriate lines of the fluid system. 

Baffles and stiffeners inside tanks should be arranged to allow free drainage to the bottom of the vessel. The bottom should slope downwards and have rounded corners. Any drain valves or plugs should fit flush with the bottom (Fig. 9.16). 

Today, the glassware required consists of either a round-bottom flask or a Schlenk tube serving as the reaction chamber. This chamber is equipped with a magnetic stirbar and a Teflon high-vacuum valve (or glass stopcock) which provides for easy vacuum control after attachment to a vacuum line (Fig. 8.7). 

---