Valve systems

Gasoline engine equipment such as carburetors, injectors, intake manifolds, valve systems and combustion chambers, are subject to fouling by the fuel itself, the gases recycled from the crankcase, or even dust and particulates arriving with poorly filtered air. Three types of problems then result ... 

Product Concentrate. An aerosol s product concentrate contains the active ingredient and any solvent or filler necessary. Various propellent and valve systems, which must consider the solvency and viscosity of the concentrate—propellent blend, may be used to deUver the product from the aerosol container. Systems can be formulated as solutions, emulsions, dispersions, or pastes. 

Pastes. Aerosols utilizing a paste as the product concentrate base differ from other formulations in that the product and the propellant do not come in contact with one another. The paste is placed in a bag that is attached to the valve system and fitted into the container. The propellant is then placed between the bag and the outer wall so that the propellant presses against the outside of the bag, dispensing the contents through the valve. 

Filtered valves contain a fine internal filter, typically below the body orifice. This filter prevents clogging by the debris sometimes found in product and package. The use of filtration is recommended with any valve systems containing body, stem, or actuator orifices of 0.25-mm (or smaller) diameter unless exceptional care is taken in the cleaning of product and package components. Valves containing these small orifices are used for products propelled by compressed gas. 

V ri ble Frecjuency Drives. An important energy by-product of soHd-state electronics is the relatively low cost variable speed drive. These electronic devices adjust the frequency of current to control motor speed such that a pump can be controlled direcdy to deUver the right flow without the need for a control valve and its inherent pressure drop. Eigure 11 shows that at rated load the variable speed drive uses only about 70% as much power as a standard throttle control valve system, and at half load, it uses only about 25% as much power. 

FIG. 26 13 Typical pressure relief system configurations (a) rupture disk system (h) pressure relief valve system. 

In controlled venting operation, the quench tank pressure is maintained at a desired level by a pressure controller/control valve system or pressure rehef valve. This mode of operation is used when the discharge mixture bubble point is close to or below the maximum ambient temperature, and it is desired to hmit the maximum quench tank pressure. 

Utilize double block and bleed pipe and valving system... 

Charge solids materials by means of a closed system (e.g., hopper and rotary airlock, screw feeder, double-dump valve system, etc.)... 

Operator exposure Charge liquids and solids materials by means of a to fumes or inerts. closed system (e.g., hard piping, hopper and rotary airlock, screw feeder, double-dump valve system, etc.) Provide local ventilation Use proper personnel protective equipment (PPE) ACGIH 1986 CCPS G-22 CCPS G-23 CCPS G-29... 

During normal operation, the valve system for the TPG expander is basieally the same as the expander in the full FCC power reeovery... 

Trip speed is the speed at which an independent emergency device is activated and sends a signal to close the expander inlet butterfly valve system. This is approximately 105% of maximum continuous speed or synchronous speed (whichever is higher). 

A typieal TPG valve arrangement is the five valve system (Figure 6-41). The two expander inlet valves provide regenerator pressure eontrol, overspeed proteetion, and flue gas shut-off to the expander. The expander exhaust valve enables expander isolation. The full and partial expander bypass valves permit aeeurate eontrol of the FCC proeess when the expander is not in operation. 

Conventional PR valves and discharge systems should be designed such that built-up back pressure does not exceed 10% of set pressure (both measured in psig), to avoid chattering problems. In the case where a pressure relief valve system is sized for fire conditions, with 21 % overpressure, built-up back pressure up to 21 % of set pressure is permissible. However, the lower rates resulting from other contingencies still must meet the 10% limitation. 

Automatic fast-acting valve system controller... 

Figure 4.1 Schematic diagram of a coupled column system. The first column (ID) is connected to the second column (2D) tlirough the interface or valve system. The interface can be a diiect coupling, a live T-union, a complex multiport valve, or a thermal or cryogenic modulation system. The stimulus can be the switching of the valve, abalancing pressure to divert flow towards 2D, an added flow that is used in pressure tuning, or the drive mechanism for the modulator. The line to detector 1 will normally be a non-retaining section of column. In a two-oven system, ID and 2D will be in different ovens the dotted line indicates separately heated zones.

Try 1/ -inch (i.d. = 1.61), since 114-inch (i.d. = 1.38) is not stocked in every plant. If it is an acceptable plant pipe size, then it should be considered and checked, as it would probably be as good pressure drop-wise as the 114-inch. The support of 114-inch pipe may require shorter support spans than the 114-inch. Most plants prefer a minimum of 114-inch valves on pressure vessels, tanks, etc. The valves at the vessels should be 114 inch even though the pipe might be VA inch The control valve system of gate and globe valves could very well be lA inch. For this example, use 114-inch pipe, Schedule 40 ... 

The Code [26] allows pilot operated vent control valves provided the vent valve can operate automatically in case the pilot valves/system failed. 

Figure 40.20 shows a typical relief valve. System pressure simply acts under the valve disk at the inlet of the valve. When the system pressure exceeds the pre-load force exerted by the valve spring, the valve disk will lift off of its seat. This will allow some of the system fluid to escape through the valve outlet. Flow will continue until the system pressure is reduced to a level below the spring force. 

As already stated, the valve system can take two basic forms, the internal loop sampling valve and the external loop sampling valve. A diagram of the internal loop valve which utilizes only four ports is shown in figure 14. 

The infusion system was similar to that described by Findley et al. (1972). The catheter was attached to a valve system that allowed slow continuous administration (55 to 60 mL in 24 hours) heparinized saline (5 units/mL) via a peristaltic pump to maintain catheter patency. Drug was injected into the valve system by means of a second pump and then flushed into the animal with 5 mL of saline from a third pump. This system necessitated a delay of approximately 20 seconds between the onset of drug delivery and actual injection into the vein. Drugs were delivered within a 2-minute period. 

The drum filter consists of a 1 to 5 m diameter cylindrical drum that rotates while remaining partially submerged in an open-feed slurry tank. The drum surface is wrapped around tightly with the filter medium. The drum shell is divided into compartments, and drain lines are connected to the central valve system that permits either vacuum or pres-... 

Many different types of valves are used to control the collection and injection of stored column effluent. We will review most of the valve systems that have been used in 2DLC and will highlight the advantages of these systems where possible. Note that there is an endless combination of these configurations. We note one excellent review (Shalliker and Gray, 2006) that contains details of valve configurations with a good level of detail. 

It should be realized also that either option shown in Fig. 9 or 10 will produce a non-symmetrical flow pattern inside the blow tank (i.e., due to preferential feeding at the blow tank outlet) and hence, promote the possibility of arching, rat holing and/or formation of dead regions. For these reasons, the combined fluidizing-discharge-cone and cone-dosing valve system shown in Fig. 8 is preferred. 

The concept of an integrated micro-fluidic-based system has now been developed (Zhang et al. 2006), with an example shown in Fig. 7. This particular system is based on conventional chromatographic instrumentation and employs a multi-valving system, located between two syringe pumps, shown in the foreground, to enable the introduction of multiple reagents from an auto-sampler to be loaded onto the micro-reactor. Because of the low diffussional distances obtained in this sys-... 

American Petroleum Institute (API), RP 14B. Recommended Practice for Design. Installation. Repair and Operation of Subsurface Safety Valve Systems. Third Edition, API, Washington, D.C., 1990. 

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