Sliding gate control valve for vacuum

[brucechase]

I hope I can get some direction from all the experts here.

I have an application that uses several small (3"-5") hand operated sliding gate valves to control the vacuum on several aspects of a machine (they push and pull on the gate to open/close it). The valves are located in a terrible location such that the operator needs to go to the back of the machine, get a ladder, make an adjustment, go back down the ladder, go to the front of the machine, see how the change affected the product.

Rinse Lather and Repeat

I would love to put a small control valve on this and adjust it via the PLC (and HMI) or even a spring return toggle switch. The PLC is a CLX so I have lots of options. The only option I don't have right now is the ability to spend lots of money.

My problem comes from the fact that I have no idea who would make something like this and how easy it would be to control (I don't want open/close - I need to change the position). I looked at a few but many of these look large and cost lots of $$. I was hope in the $500-$1000 range and I could probably sell it to the bosses.

Does anyone know of some good sliding gate valves (or even other types) that will do what I want? Any manufacturers that are good to work with on this? Thanks in advance for any help.

 

[TConnolly]

Hello Bruce.

Pneumatic sliding gate valves are very common on high vacuum equipment. They usually employ an air cylinder and rack and pinion drive to move the gate. Most are only fully open or fully closed.

If its a high vacuum system then look at supplers such as Varian or Lesker or Helix or Edwards. They can be very expensive, running several thousand dollars each.

I'm wondering if you have a high vacuum application because it sounds like you are using them to adjust flows and since that is somewhat meaningless is high vacuum applications I'm not sure if that helps you or not. If these are the sheet metal gate valves used on dust conveyors then the valves I linked will not be suitable.

 

[brucechase]

Alaric, thanks for giving me the links. I'm not sure that these would be considered a "high vacuum" application.

What exactly defines a high vacuum?

Yes, these are sheet metal slide gates. It is used on a machine that has vacuum conveyors that hold a product down for high speed applications. We change the product regularly and thus have to adjust the vacuum on the conveyor for product conveyance and processing. The products are similar to a 3"X3" piece of thin felt (running at 1000 pieces per min) and will vary in size and density depending on what we are doing. Once the vacuum is set, we don't change it until we start a different product run.

Looking at your recommendations, it does seem to be a bit overkill for what I want to do.

 

[shawn_75]

Perhaps a linear actuator? Inexpensive, lots of force and some provide position feedback.

http://www.firgelliauto.com/default.php?cPath=109

Shawn

 

[DamianInRochester]

Bruce,

With the money your talking, your probably looking at rigging something up to drive what you already have. Specifically how is the adjustment now performed? Are they turning a knob to drive a nut? If so, how many turns from full open to full close and also how much distance from full open to full close?

I have seen some nice little sensors from Pepperl-Fuchs and others that mount like a prox and can give you an analog position feedback on the cheap.

A picture of what you have now would also do wonders.

 

[keithkyll]

High vacuum is below 1x10-3 Torr. Beyond what a mechanical pump can do. You are working in the medium vacuum range.
What you need is a Throttle Valve. Here's one on eBay. I also searched for Motorized Butterfly valve. That might work.
Another way is with a controlled leak. Add a little air to drop vacuum. That would probably add quite a burden to your pump.

 

[brucechase]

Currently the adjustment is done by pushing or pulling on the slide gate. The operator, after climbing the ladder, just takes his hand and hits it with his palm to move it slightly. Not a lot of force, but just grabbing it takes more force than tapping it (don't want to fall off the ladder).

I do like the linear actuator. Feedback really isn't a must have. They don't look at the position, just the product going down the conveyor and the vision inspect system for feedback. Sometimes it takes 30 minutes to get it right (lots of wasted product).

The throttle valve is nice, but it looks overkill for my application. I really didn't want to use the air leak method. The actual system is on a vacuum header with about 12 small vacuum systems coming off of it. I only need to adjust a couple of them.

I will try to get a pic this afternoon.

Thanks for all the help so far.

 

[Clay B.]

Low tech would be to simply use a slide gate attached to an air cylinder. You can crank the flow regs on the air cylinder so that the cylinder moves real slow. The all you would need is a 4 way solenoid valve. You could then put push buttons on your operator panel that "bumps" the valve open or closed.

 

[TConnolly]

Bruce, the valves I linked are for applications in the millitorr to microtorr pressure ranges, which is about 100,000 to millions of times more vacuum than where you are apparently working.

A motorized damper might work well for you. Check with HVAC dealers. Maybe something like this: