Venturi Pump legality

[burde1jb]

Oh wise members of CD:

Last season we began with a very interesting idea to manipulate the game piece: Vacuums. Specifically Venturi Pump style vacuums. A mentor brought in some very cool equipment which was demonstrated to hold on to the totes and bins very well, but I said no as I did not think they would have been legal. Please note the picture uses water as the medium, but our devices would have used the pressurized air.

According to the manual R66 , any device which creates a vacuum would not be subject to the pneumatic rules. However, a Venturi pump would utilize the pneumatic system components.

Would such a system have been legal last year? Thoughts!

[GeeTwo]

Compressed air (needed to create the vacuum) must be provided by a single ~1 cfm compressor. Would that generate enough vacuum to do what you wanted to do with it? Since you can only use 1/8" NPT solenoid valves, you can't store air unless you're using a lot less air than I'm expecting you to need, or use a lot of solenoid valves which means a lot of venturi vacuums since you can't plumb the outputs together.

[Mark McLeod]

Team 28 used a vacuum pickup last year, but they generated it by mounting a CIM to a suction pump.
It worked great and picked up totes and cans no matter the orientation.

Venturi pumps were included in the KOP for several years, although this was several years ago .
They work well for the smaller game pieces, but forming an efficient seal is critical, because the volume of air is necessarily low with the supply on the robot.

[Jon Stratis]

Originally Posted by burde1jb

Oh wise members of CD:

Last season we began with a very interesting idea to manipulate the game piece: Vacuums. Specifically Venturi Pump style vacuums. A mentor brought in some very cool equipment which was demonstrated to hold on to the totes and bins very well, but I said no as I did not think they would have been legal. Please note the picture uses water as the medium, but our devices would have used the pressurized air.

According to the manual R66 , any device which creates a vacuum would not be subject to the pneumatic rules. However, a Venturi pump would utilize the pneumatic system components.

Would such a system have been legal last year? Thoughts!

Venturi valves are interesting when it comes to the rules - half of the valve is considered pneumatics, while the other half isn't. So as others have mentioned, you would have to run the valve off of a legal pneumatic system, which (probably) couldn't generate enough airflow to create sufficient vacuum to pick up a tote. My team tried them way back in Rack N' Roll, and couldn't quite get it to pick up an inner tube!

When teams want to use a vacuum, most often they'll take something like a shop vacuum apart and replace the internal motor with a legal one. It can create a LOT more suction for you that a venturi valve can with our pneumatics limitations!

[FrankJ]

1311 (Kell) did use them last year on their tote manipulator. So never say never. The totes have a rigid surface for the suction cup to stick to which probably easier to get the initial seal than a tube. The eductors are very air hungry.

[burde1jb]

So what I'm reading is that they would have been legal, but some believe the amount of air necessary to achieve the vacuum would be difficult given the equipment available.

To clarify our position and perhaps make our case for future use, I've attached a couple of pictures. The first are the suction cups used to attach to the totes and bin. Any roughness of a surface is accounted for by the foam "lips" on the cups seen in the picture. We were able to pick up totes from all side as well as the bins from any angle.

The second picture was a device to monitor the vacuum. This shut off the air supply once the vacuum was achieved to prevent unnecessary pressure loss.

I think this would have been a really neat application, but I was just too uneasy about its legality as well as practicality given the provided equipment.

Thanks for your input and I thought I would share this for anyone else's use in the future!

[Mark McLeod]

The only inspection issue that I think you would have to address with that Venturi device (not the suction cups which are down stream, but just the first photo device) is that as a connected pneumatics part it must be officially certified to pass the required FRC pressure rating rules.
For instance, you would need a spec sheet for the device that it is rated for 120psi or greater (or whatever the season rules might specify).

[GeeTwo]

I strongly suspect that you could get far more vacuum with a vacuum pump (fitted with an FRC-compliant motor) than Venturi behind a 1 cfm compressor. Another alternative would be a vacuum cleaner or a squirrel-cage fan with a duct sealed over the intake, either powered by an FRC motor; this would be less expensive, and the modification would probably be easier.

[dradel]

You can also create vacuum using pneumatic cylinders. Use the port that would normally extend the cylinder when pressure is sent in, the pull the rod end up and presto vacuum.

[GeeTwo]

Originally Posted by dradel

You can also create vacuum using pneumatic cylinders. Use the port that would normally extend the cylinder when pressure is sent in, the pull the rod end up and presto vacuum.

For a short-term vacuum, this could definitely work. If you need vacuum for an extended period of time (more than a handful of seconds), you'll want something that can provide continuous vacuum, whether venturi, fans, vacuum cleaner, classic vacuum pump, or otherwise.

[EricH]

Originally Posted by GeeTwo

For a short-term vacuum, this could definitely work. If you need vacuum for an extended period of time (more than a handful of seconds), you'll want something that can provide continuous vacuum, whether venturi, fans, vacuum cleaner, classic vacuum pump, or otherwise.

Depends somewhat on the application, and how much vacuum you're actually pulling.

I'll vouch that for short-term pickups without a lot of shock loading, it'll work fairly well. And it'd probably work for somewhat longer runs if you had enough. The problem is that FRC robots get rocked a lot... I've seen two teams attempt this in one season (it's been a while, though), with some degree of success. I was on one of those teams. We took the device off because, while it fit part of our strategy, it didn't fit the rest properly and couldn't hold suction in a shock situation. (It was replaced by a long piece of fiberglass pultrusion, actuated by the cylinder that had supplied the motion to the vacuum-generating one--lost half the job, kept the really important half.)

[matthewdenny]

Just so you know, I had no idea what a Venturi Pump was when I started this article, but reading this. A little internet research later, I do, and this is why I like CD.