Control Valve

To control things...!

Look around you ...think...look at a hydraulic digger, fork lift truck...the brake master cylinder in your car.

Ask yourself how these things work...use the internet to check these items...don't expect people to just tell you, 'cos you'll only forget anyhow.

Del the cat lets you thinkfor yourself--all these ON-OFF Control Valves!

But are you meaning the Flowrate-Controlling Throttle Valves for Chemical /Thermal Processes?

Then you have to go deeper into Seat geometry,Cν, Cavitation,Stellited Seats/Plugs ,Pneumatic Positioners, Motorized Position Controls, Stepper motors, Distributed Controls,ProfiBus------->.

Better to have a long Session with Your Chemical Engineering Professor

There is some proportionality in a car's braking system and positioning of a digger's arm.... but I take the general point that I've only touched on a small part of the control valve spectrum!

Del

This being your senior year in a mechanical school, you should by now, already have an understanding of main entinties used in diverse applications, such as a control valve. Plus, from reading your request, it seems you are from a less fortunate area of the world in your quest of a higher level in education. I really do not mean to be so brash and interuptive, but, for your understanding in the mechanical engineering world, you need to study more resources to gather the needed information.

Control valves are designed in many forms for many types of applications. Fluids of all sorts, each being a specialized format for its' particular application. Then there are valves used in dry solutions as well, which is sililar to fluid valves, but the type of packing seals will be the difference in regaurds to the internal designs. Valves can be conttrolled by air, electrical, and even with a fluid control media. It all depends in the environment that particilar valve will be use in and for what materials it is to control.

All valves are designed in two basic forms, one being a ball gate, and the other being a flat gate opening at a perpindicular to the flow direction. You can find all this information ion the wikipedia registors on the web.

Good luck guest.

Maximo

All valves are designed in two basic forms, one being a ball gate, and the other being a flat gate opening at a perpindicular to the flow direction.

Hmmm. Maybe you've never dismantled an automtive brake master cylinder?

The piston moves axially along the bore opening and closing ports as it does so. I would think this is a fairly commom arangement?

Ah, I s'pose it is sort of perpendicular to the flow at the point where it opens/closes.

Anyhow this all adds to the answer I s'pose!

Del, I must add my agreement to your remarks on the quoted statement. Without the spool valve, our modern hydraulics would be sorely lacking in control.

Maximo, I don't know from where you hail, but the "ball gate" you refer to is something I am not acquainted with. Perhaps you mean the globe valve, varied in design and widely used in control applications. The "flat gate" you refer to is only in the rarest of situations flat. It is referred to as a gate valve (tapered gate and seat for sealing) and is rarely used for control purposes due to the flow characteristics across the gate. I trust this is what you meant.

Simple Question - simple answer:

Suppose you have a manual valve (ball/butterfly/gate/globe) any size and you are tired of opening and closing since you need to be present there to do so. Thats means you got to be there all the time. you cannot be there all the time because you need to study, go to the wash room, go to eat, go for a date (since you are final year), go to sleep and so many things. Or , siomply you get tired of opening & closing the handle of the valve. Then what do you do?

You act smart by putting a Control Valve - easy.

Stage:1

Now the simpliest control valve is an on/off "solenoid valve". It has 2 wires coming out of it. Now you can connect these wires to an electrical switch. push on/off - relieves you the problem of manually opening/closing. Life starts getting easy yet, you again got to be there all the time to switch on/off. Now you get more smart by connecting this to a timer. Now you can set the time for the control valve to go on/off.There you can now perform all above stated personal functions.

Stage:2

Again, to get more smart - if there is pressure/temperature then instead of timer you connect the control valve to a pressure switch/ temperature controller to again go on/off with pre-set pressure/temperature.

Stage:3

Now if you come across application of the same control valve as: hazardous conditions where electrical cannot be used, or the application calls in for slow opening/slow closing, slow opening/quick closing, proprotioning then, you have to seek help for you may not be that smart.For these application the solenoid on/off is replaced by Pneumatic actuated/ Motorized Control Valves, control Valve positioner which can be pneumatic/electro-pneumatic and yadda yadda yadda.

The yadda yadda yadda are application datas required as: media, type of fluid, temperature, pressure, flow, description of unit where it be installed, unit's utility data, back pressure etc.

When you cross Stage 1 let me know and I will then help you out.

Is "yadda yadda yadda" a terminology or a native slang?

What's happening to our education system? A final year ME student is clueless on valves?

Quite.

Control valves are the ones which help in effective handling of fluid power. Hydraulics & pneumatics are as destructive as anything when the total system is out of control.

Basically control systems are of two types Directional control & pressure control.

Directional control valves(DCV) are used in controlling the path of flow of the fluid.Thus enabling us to perform actions like Extension and retraction of a cylinder.

Pressure control valves play major role insafeguarding the system by maintaining the required pressure. For eg. A pressure relief valve opens when the system pressure exceeds the set pressure, thus reducing the resistance & reduces the pressure.

For more details go through books like Fluid power by Antony Esposito

To: "Student Of Final Year Mechanical"

You have recieved a lot of responses to your question and some of them even give some good information that are partial answers.
I have over forty-five years in the process plant engineering and design field. I will try to give you some of what I learned about "control Valves." By process plants I am talking about refineries, chemical plants, petrochemical plants, power plants, food processing plants, along with plants for the making of soap, paper, steel, aluminum and glass.

A Control Valve is normally only one specific device in a "loop" (system) that controls a peramater effecting a process. There are four main peramaters and a few minor peramaters. The four main peramaters are: Flow, Level, Pressure and Temperature. These four make up (maybe) 95% of the control peramaters in any process plant. The other, or minor peramaters include: weight, thickness, humidity, density, Ph, color and viscosity to name just a few.

A control Loop (system) will normally be made up of a sensor device(a) to read the desired control point, then a transmitter(b) to send data, then a control board unit to display(c) and or record the data(d), then a set point controller(e) with a relay followed by the control valve(f) itself.

So let's say we are interested in the level of liquid in a specific tank when we are filling that tank. We would need some type of device(a) to read the level in the tank. Then we would need a transmitter(b) to send the level data to the control board. On the control board we would need a display gage(c) to indicate the current level. Then we would need a recorder (d) to record the level. Then we need to have a set point controller (e) because sometimes the process requires changes to the primary level. When the correct level reaches the "set point' then a signal is sent to the control valve acturator to close the valve(f).

In the second paragraph I said "normally" when defining a control system. The exceptipn are the "Self Contained Pressure Controllers." These devices are a control valve that do not have the type of "Loop" described in the previous paragraph. They are in fact self contained. They come in two types. One is made to control the pressure up-stream of the valve. The other is made to control the pressure downstream of the valve.

Control Valves come in many different "body" types and configurations and, as has been noted by others, can have different types of actuators. The most common body type is the "Globe" type body. There are also variations in the globe type body. There are single seat and double seated globe type bodies. There are also straight pattern bodies and angle pattern body control valves. Other valve types can be fitted with an actuator and thus become a control valve. These include the Butterfly valve, the Needle valve and the Diaphram valve.

The "Acturator" is the part that operates the valve. Actuators might be pneumatic, electric solenoid, electric motor or hydraulic.

Piper brings it to the point.

I just got threw signing joint venture agreements with two valve companies, one Butterfly Valve and the other being a Control Valve company and my engineers could not have explained better than PennPiper, you definetly have the right information.

control valves ,,, pretty vague question, kitchen sink faucet, toilet bowl shutoff , fuel injectors, river dams with flood gates, etc, etc, etc,steam , water, oil, mollasses, fat, acid, everything under the sun basically, all in a variety of actuation methods , mechanical, electrical, pnematically, hand operated. what exactly are you wanting to know, "final year Mechanical student"?

jack

CR4's are going to be going to my junk e-mail folder. I can't take the third world's dumb questions and the first world's poor spelling and grammar anymore.

Good Bye

Hey 23 posts...we're really going to miss that guy...

did wilyecoyote have a tough weekend? or possibly came in a runner-up in a spelling bee and still harbor's some resentment for spelling errors. It does not matter how it is spelled or explained, we are not perfect all the time and all kidding aside, if you understood the individual it is good enough in my book. RELAX

Wilye

Tolerance is a good thing; really, it is.

Don't go away mad, just go away.

Hupe me spilling und gremmar chuck ourt too yer satisfliction.

I am new to this forum, but I have to tell you, the comments are helping me pass the day, because even though I run two start -ups this is a good distraction and to be honest i do have a problem getting started on mon. maybe wiley needs a control valve for his anger just maybe

Partypooper!

The control valves are used to control :

• Flow rate

• Temperature

• Pressure

• Level

• Viscosity