Piston-cylinder example types

A simple example of an area meter is a gate valve of the rising-stem type provided with static-pressure taps before and after the gate and a means for measuring the stem position. In most common types of area meters, the variation of the opening is automatically brought about by the motion of a weighted piston or float supported by the fluid. Two different cylinder- and piston-type area meters are described in the AS ME Research Committee on Fluid Meters Report, op. cit., pp. 82 3. 

A common type of work associated with chemical processes is work done by a gas (through expansion) or work done to a gas (through compression). For example, in an automobile engine the heat from the combustion of the gasoline expands the gases in the cylinder, pushing back the piston. This motion is then translated into the motion of the car. 

We should not be too narrow in our choice of terminology if we want to discuss systems of more general type, i.e., those made up of more than just one phase, such as systems like the gas plus cylinder and piston, or a galvanic cell as a whole. If, for example, the term —p AV is replaced by —F Al or the term —A d by —U AQ (where U is the voltage and Q the charge), we obtain the following equation. 

Next, we will explain the operation and components of manually activated and pump-driven hydraulic systems. Examples of these types of hydraulic systems are depicted in Figures 10.13(a) and (b). Figure 10.13(a) shows a schematic du ram of a hand-driven hydraulic jack. The system consists of a reservoir, a hand pump, the load piston, a relief valve, and a high-pressure check valve. To raise the load, the arm of the hand pump is pushed downward du action pushes the fluid into the load cylinder, whicji in turn creates a pressure that is transmitted to the load piston, and consequendy the load is tai d. To lower the load, the release valve is opened. The amount by which the release valve is opened will determine the speed at which the load will be lowered. Of course, the riscority of the hydraulic fliud and the magnitude of the load will also afiect the lowering speed. In the system shown, the fliud reservoir is necessary to supply the line with as much fluid as needed to extend the driven piston to any desired level. 

Now imagine carrying out the same reaction in a metal cylinder with a movable piston. As this explosive decomposition proceeds, the piston in the metal cylinder will move. The gas produced in the reaction pushes the cylinder upward, thereby increasing the volume of the container and preventing any increase in pressure. This is a simple example of mechanical work done by a chemical reaction. Specifically, this type of work is known as pressure-volume, or PV, work. The amount of work done by such a process is given by... 

Dead-weight accumulators are obsolete and only very few have been constructed during the past 20 years. They consist of a vertically arranged cylinder whose piston is loaded by a heavy weight made up of cast-iron plates or a vessel filled with ore or scrap metal. The weight depends on the water pressure required it amounts, for example, to about 140 tons at a piston diameter of 300 mm and an operating water pressure of 200 atm. The drawbacks of this accumulator type are its large overall... 

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