Opening and Closing Speed of a Valve

How about a stop watch.

I was looking for something a bit more precise...

Thanks

What's the reason for 0.75 s? Can it be less than that? Do the valves need to be synchronized?

Speed of closing (or opening) can be adjusted by using needle valves in the air line.

More info would be nice.

Is there any external indication of the state of the valve? If so, you could use "something optoelectronic" (more information needed).

Failing that, all you could do is use pressure or flow sensors upstream and downstream. You'd need to know the sensor response times (which I suspect would be pretty big compared with your 0.75 second requirement). You'd also need a signal to indicate start-of-operation.

Could possibly be an acoustic signal as the valve leaves and reaches the extreme positions. A contact microphone and an oscilloscope would give you the timing.

Hi JohnDG,

Good suggestions. I was thinking photoeye too, but wanted to get more info. I find it quite maddening sometimes to have a hunch at what the OP is looking for, but the information given is so severely lacking.

Sometimes it seems like we're running after OPs, shouting questions at the back of their heads as they're walking away, as if the onus is on us to give them a GA by (literally) guessing.

I suspect here that if we had more info, a solution could be found fairly quickly.

Need...... beer...

Porky

The presentation is disjointed. If you have a valve actuator and regulator, THAT is what needed be focused on. Then the valve or whatever is almost immaterial. Unless there are mechanical stops you also forgot to mention.

As stated in line speed controls at the actuator could be used, and even if a namur mounted solenoid is used a speed control block can be purchased from certain manufacturers'. If these have positioners and you are using them as control valves, depending what type of positioners you may be using you can adjust the speed in the software of the positioner. All aspects need to be taken into consideration with all processes being running.

Did you say 0;75 seconds(means 0 to 75 seconds?) or 0.75 seconds?That is FAST!

Are you wanting Fully Shut to Fully Open operations. Fast Air Cylinders with air storage next to each actuator is needed.Commands will have to be Electric.

Or maybe you want to preset the Limit of Opening/Shutting. NOW You need local Computers at each Digital Stepper motor actuator. 0.75 Second will be NO-NO.

Don't you have Water Hammer like situations as Abdel posted?

Suggest you re state your problem.

"If you can state your Problem- you have half solved it"

0,75 seconds.... closing speed is a big issue.. this process has 12 valves, ranging from 30 " to 6 " valves... they do not have limit switches, and they have work together.. while one opens the other has to close, one cannot close before the other opens, or a shutdown or the process will be unstable.

Achiveing the speed control is not my problem, I was just looking for a tool (without having to build one) to adjust the opening and closing speed of all the valves to 0,75 seconds...

Using a stop watch is what I do now, but its time consumming, and least we forget we take a fraction of a second from when we see to when we press stop... and as I am sure you can relate too .. I don´t have that fraction ...

Thanks for the replies... even to the guy who called me an idiot..

God bless and have a Great Easter !!

How do you currently know the state of the valve? How do you switch it locally? Can you post a link to an image (or datasheet) of a similar valve?

We cannot read minds.

Software is a beautiful thing! I have had a similar situation on a group of line valves. The biggest issue that you may over come may be when the valve is really closed, that means no process going through it. I am taking for granted that you have mechanical stops on the actuators as well. All valves would have to be sure of closed as well as open per spec. There are a few more ways to check operational characteristics of the valve as well as speed. If the valve has been is service for a while, well even "new" if the valve is not properly set, or mechanical components for it are not proper, the hysteresis is there as well to take into consideration. Many companies make a in line test to check such things but none of them are quick, nor cheap.this is just an FYI if you haven't covered, or thought about any of these aspects yet. After all is taken into consideration there are many ways to accomplish with what you are trying to accomplish. Timed solenoid valves is another way as long as process conditions and differential pressure do not change immensely. Nothing will be a quick solution. Good luck.

"Time Consumming" -- did you say .

And that too within 0.75 Seconds

You must be a Superfast-SuperSpeed robot .

Must meet you Porky

I doubt that one should close a 30" valve within 0.75 seconds; that would be like stopping a train or a ship. A P&ID for this process, together with the operating sequence, would be informative.

If the buttefly valve assemble together with the positioner, you can use the positioner software to measure the valve opening and time.

If not, you can see it from the valve indicator and stop watch. :)

The Snubber can only SLOW

Porky needs FASTer

And he needs BOTH ways FASTer--

So?

If your valves have visible mechanical position indication, have you tried using a digital camera [or video camera] which can take short video with frames at 25/second or so?? Transferred into a computer, it would give you a permanent record.