Motorised valves

[vinke]

Hey guys,
Im on a cooling system project and ill be using motorised valves.I dnt really know how they work,i mean if i want to close or open it wat type of signal should i apply?And what happens if i apply a signal and the valve is completely closed ,does it continue to close the valve even if it is closed?It is an ac type motorised valve.
I would be really grateful if someone could help...
thanks

 

[Nigel Goodwin]

You apply power and it opens, you remove power and it closes - it's really VERY simple.

 

[vinke]

ok but wat happen if power is continuously fed into it while it is open?

 

[phalanx]

ok but wat happen if power is continuously fed into it while it is open?

Depends on the valve. If it is a solenoid type, it will remain open as long as you apply power. If it has some sort of rotational motor and gear train, I would hope that it has mechanical stops. The valve would then open all the way and effectively stall the motor when it reaches the stops. The motor could overheat if it wasn't designed to be powered in a stalled state.

The datasheet of the valve should tell you everything you need to know.

 

[Hero999]

I don't know about valves but you can get magnetically latched relays, power them in one direction and they turn on, power them in the other direction and they turn off; I would assume the same is also true for valves.

 

[CheapSlider]

Hello Vinke, a quick overview of Motorised valves

MVs are similar to manually operated valves such as are used for plumbing. The most common application in the UK is in central heating.

A popular valve is a " 2 port motorised zone valve". (EG Honeywell **broken link removed**. -a very common MV and easily available in the UK)*

This is a "spring return valve" which will normally be closed (IE it will stop the flow of water through it).
When power is applied the motor will open the valve which will stay open while the motor is powered. Once power is removed the valve will close.
There can be a choice of motors, the most common type of motor used in UK heating systems is a synchronous motor working off 230V AC. The motor uses about 6W and takes about 10 seconds to fully open the valve. Other motor types (EG 24V DC) are available.

Some valves will have a switch which will operate when the valve is fully open. This is not a limit switch, its used to signal that the valve is open.

The most common reason for the valve to fail is burnt out motor. The motor can be replaced without needing to change the whole valve.

*see also 3 port diverter valve EG **broken link removed**

 

[Nigel Goodwin]

ok but wat happen if power is continuously fed into it while it is open?

It stays open, that's how it's supposed to work!.

 

[Sceadwian]

As long as you buy a purpose built unit they have safety features or feedback built in to keep them from self destructing. Just find the manual for your particular valve to learn more, there are many different types so your question is really impossible to answer without more information.

 

[vinke]

Thanks guys your posts have been very helpful...

 

[waginia]

Itis decided by the type of the valve.if it if on-of valve ,it will open when it gets high voltage,otherwise it will be closed.But if it is solenoid contril valve,the result is not same.The opening of th valve will continually changed proporyional to the standard elctrical input signal!

 

[Sceadwian]

You mean servo control valve yes? Solenoid's are just dumb push pull devices. A 'servo mechanisim' can use any methods it wishes 'solenoid, standard motor, direct mechanical' the important part is that a servo motor has feedback so it can apply force based on it's current position or force and desired position or force.