Accessories of Control Valve

[scdaiwei]

I am a newer to Control Valve. I have some questions about graphs below. The accessories of Control Valve is the strangers to me. Could you help me?
Please see the attachment graphs.
Thanks in advance.

 

[scdaiwei]

This is another attachment graph.

 

[IGRECA]

Hi Scdaiwei,

it seems that the 2 accessories on the right side are volume boosters type Fisher 2625.
Hope it will help you.

 

[terje61]

Hello Scdaiwei,

The first picture is not perfectly clear to me.
- What is evident is that the part in the bottom right is a filter/reducer to make sure you have clean supply pressure that is not overpressuring your actuator.
- The item in the bottom left looks like a selector valve. Normally used for manual override or testing the valve.
- In the top left you have a volume booster. Included to increase the operating speed of the actuator.
- Top middle can be several things. I am not sure, but I expect that these are high capacity filter/reducers.
- Top right looks like just a gauge on a cross-connector. To show the inlet pressure.

The second picture is easier.
- On the right you have a Fisher booster type 2625 as mentioned by Igreca. This is also used to increase the operating speed of the valve.
- On the right is a Fisher trip valve type 377L. This is used for making sure that the valve has a fail function when the supply pressure is lost. The fail function can be fail lock by blocking all exits or fail open/close by connecting one exit to an accumulator. Since the boosters are placed after the trip valve it must be fail open/close, because the fail lock function is overruled by the boosters.

TIP:
You can look at the nameplates of the equipment what the manufacturer and model is.

Best regards,
Terje

 

[scdaiwei]

Thank you very much.
I have an idea of them.
But I don't know the function of the selector valve of the first graph said by terje61. Could you speak more in detail.
In addition, I have other two graphs to bother you.
This is one control valve with different side photographs.

 

[scdaiwei]

The second photographs

 

[khan101]

The right hand side devices look like volume boosters for open and close position. The left side device is a lock up device. Volume boosters will make the valve move quicker. Lock up device will keep the valve in last position in case of air failure, since this is a piston type actuator and at air failure, valve will eventually close.

 

[terje61]

Hello Scdaiwei,

The new pictures do not make it much easier, but I will write down some possibilities.

A selector valve is normally used as follows:
In position A: port 1 and 2 are connected. The output of the positioner is connected to the actuator via the boosters. The valve works on automatic 4-20 mA control.
In position B: (90 degrees turn): port 1 and 3 are connected. This might be to manually open the valve.
In position C: (180 degrees turn): port 1 and 4 are connected. This might be to manually close the valve.

The manual positions can also be for (partial) stroke testing / valve blocking or any other operation. Without a clear schematic drawing this is difficult to determine.


Getting back to the top/middle item in the first picture this might also be a biasing relay (e.g. make Fairchild). You can use a biasing relay as a trick to increase the actuator pressure and this way select a smaller actuator. In a biasing relay the following equation is applicable: Po = Ps + K
(Po = output pressure / Ps = supply pressure / K is adjustable constant due to internal spring)

This explanation is also applicable for the top item in the last picture and in the third picture.

I hope this helps.

Regards,
Terje

 

[scdaiwei]

Thank you.
I have better knowledge acquisition of it.