BALL VALVES AND PLUG VALVES

Ball and plug valves are designed to both isolate and throttle flow, depending on the requirements of the process.

They are used where wuick switch over from fully open to fully close or vice versa is required. These are used for fluids containing suspended solids. 

CHECK VALVES

Check valves or unidirectional valve:

                                                      Check valves are used when unidirection flow is desired. It is opened by the pressure of the fluid, whent the flow stops or tend to reverse the direction the valve automatically closes by the action of gravity. common type of check valves are lift check and swing check valves. 

 

CHECK VALVE

VALVES

Gate Valve:

                                    gate valves are designed to isolate flow.this type of valve has two useful position,fully open and fully closed. if the gates is left half opened an eddy is formed behing its disk and cause the valve to vibrate. The gate valve introduces a small pressure drop.

                                                                   GATE VALVE

Rising stem gate valve:

                                  In this the  stem is not connected directly to the handwheel.

Non-risisng stem gate valve:

                                          In a non-rising stem gate valve the stem is connected directly to the handwheel.


Globe Valve: 

                                        They are designed to throttle or regulate flow. The disc can be placed in many different positions between fully open and fully closed. Pressure drop in this valve is large because the fluid passes through a restricted opening and changes direction several times.

 

globe valve               

why cooker cooks the food quickly?

As we know that boiling point is directly proportional to the atmospheric pressure,if the external pressure increased the boiling point of water will also be raised. This is done in closed container or pressure cooker from where the vapours are not allowed to escape,hence they develop more vapour pressure within the cooker and thus the boiling point of water increase and cooks the food quickly.

 

why evaporation causes cooling?

After the collision between molecules some molecules acquire higher energy,then molecules of higher energy escape in air in the form of vapours. The kinetic energy of remaining molecules decreases.the temperature will also falls, hence cooling is caused.