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-   -   Layout of off-board compressor (featuring sweet pics) (http://www.chiefdelphi.com/forums/showthread.php?t=128588)

tkbletsc 07-04-2014 13:50

Layout of off-board compressor (featuring sweet pics)
 
Our team is doing an off-season build competition that may involve pneumatics, but we don't have a compressor for every team. This means doing an off-board compressor design, but I can't find much info on how to actually do that.

Here's the standard pneumatic layout:


If I charge the system and simply remove the compressor, the air just escapes.


So what if I put a valve after the compressor?


That way when the system is charged, I close it, then remove the compressor.


Only one problem: if I accidentally leave the valve closed when I charge, I'm going to be charging just 6" of tube, and I'm going to have a bad time.


We have the emergency relief valve on the compressor, but I'd rather not rely on that. How are you "supposed" to do it?

Jon Stratis 07-04-2014 13:59

Re: Layout of off-board compressor (featuring sweet pics)
 
See images 4-16 and 4-17 in the Robot Rules, R85/86.

You need to have the pressure relief valve (the blow off valve set to 125PSI) attached directly to the compressor, and a second relief valve on the robot (R87)

You can have the regulator, pressure switch, and pressure gauge (for stored pressure) either on board or off board, so long as they are all together - either all on or all off. If they are off board, then you only have 60 PSI available for storage on the robot.

Most teams will plug it into the manual pressure vent valve in order to charge their system. If you do this, make sure there is a second manual valve somewhere so there is a way to relieve the pressure manually even while charging the robot.

tkbletsc 07-04-2014 14:15

Re: Layout of off-board compressor (featuring sweet pics)
 
I'm sorry, I still don't understand. In the pictures you referred to, what prevents all the pressurized air from escaping when you remove the compressor?



Whoosh:

Jon Stratis 07-04-2014 14:34

Re: Layout of off-board compressor (featuring sweet pics)
 
The pictures don't show it, but you need to have a manual valve in place on the robot side that you can close to prevent the air from escaping.

Jared Russell 07-04-2014 14:42

Re: Layout of off-board compressor (featuring sweet pics)
 
Quote:

Originally Posted by tkbletsc (Post 1370518)
We have the emergency relief valve on the compressor, but I'd rather not rely on that. How are you "supposed" to do it?

That's what the emergency relief valve is there for.

cbale2000 07-04-2014 16:29

Re: Layout of off-board compressor (featuring sweet pics)
 
What you need to do is get one of these (similar ones can be found in assorted pneumatics parts that come in old kits or from FIRST Choice):



and connect one of these to it:


Nate Laverdure 07-04-2014 16:38

Re: Layout of off-board compressor (featuring sweet pics)
 
Schematically, your legal options look like this:

Standard "on-board" compression


"Off-board" compression


"Seriously off-board" compression

Chris is me 07-04-2014 16:48

Re: Layout of off-board compressor (featuring sweet pics)
 
For our robot this year, we would plug the offboard compressor into a fitting attached to a manual valve. The other end of the manual valve was attached to a T, which itself was attached to an additional manual valve and our stored pressure regulator / automatic relief valve. After this collection of brass and hardware, we ran a tube to the first storage tank and the rest is the same as an on-board setup. I can post a picture if needed.

CENTURION 07-04-2014 23:20

Re: Layout of off-board compressor (featuring sweet pics)
 
You could also hook up a quick-disconnect fitting like this one:
http://www.hydraulic-supply.com/imagesorg/aqpfd41.jpg

Instead of having a manual valve at the point the compressor attaches.

It solves your problem of accidentally trying to charge only a 6" section of tubing, instead of the whole system.

It's also designed to be connected and disconnected many times, whereas the standard kind of tubing fittings used in FRC are really not meant to be used that way (Though they do hold pretty up well under that sort of use).

You can put the male connectors on each pneumatic system, and just one male connector on the hose/tubing coming from your compressor.

Another bonus: These can often be found at local hardware stores, they'll probably be with the air tools (Nail guns and the like).

As far as I know, these connectors are legal for FRC use (Though as you said this is an off-season project, that may not matter).

As others have said, you do need to have a pressure relief valve on the compressor. It's not just the rules; it's so that you don't blow anything up :D

Chris is me 07-04-2014 23:45

Re: Layout of off-board compressor (featuring sweet pics)
 
The quick disconnects don't seal themselves when not in use? You still need a manual valve between the quick connect and the rest of the system.

BBray_T1296 07-04-2014 23:56

Re: Layout of off-board compressor (featuring sweet pics)
 
Quote:

Originally Posted by Chris is me (Post 1370910)
The quick disconnects don't seal themselves when not in use? You still need a manual valve between the quick connect and the rest of the system.


The female quick disconnects automatically seal. I think he made a typo

rich2202 08-04-2014 07:29

Re: Layout of off-board compressor (featuring sweet pics)
 
Quote:

Originally Posted by CENTURION (Post 1370898)
As far as I know, these connectors are legal for FRC use (Though as you said this is an off-season project, that may not matter).

It is an R77-f part. Make sure it is COTS, and bring the pressure rating.

R75 - Must be rated for at least 125 psi. If rated for less, at a regional, we will let you use it if your switch and pressure relief valve are set for the lower rating (robot compliant with the spirit of the rule). At the championship, I am guessing they will not let you compete with the under rated component (robot fully compliant).

m1506m 08-04-2014 11:06

Or use a Schrader valve

JamesCH95 08-04-2014 11:29

Re: Layout of off-board compressor (featuring sweet pics)
 
+1 to the quick disconnect idea. They come in very small sizes if weight is a concern. This is a standard in multiple industries for repeatedly connecting and disconnecting air lines. IMO this is how one is "supposed to do it."

CENTURION 11-04-2014 23:16

Re: Layout of off-board compressor (featuring sweet pics)
 
Quote:

Originally Posted by Chris is me (Post 1370910)
The quick disconnects don't seal themselves when not in use? You still need a manual valve between the quick connect and the rest of the system.

Quote:

Originally Posted by BBray_T1296 (Post 1370919)
The female quick disconnects automatically seal. I think he made a typo

Oops! Yes, I meant to say that the female connectors should be on the pneumatic system, and the male connector on the compressor.


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