pic: In-Line Pneumatic Fittings

[EricH]

Originally Posted by TheHolyHades1

Is it worth using these type of fittings when the brass fittings do a good job in serving as a heatsink for the compressors?

Just as a note: If I'm not mistaken, these would be located well downstream from the compressor, say on the other side of the storage tanks. This isn't the pressure relief valve, it's a regulator. The PRV has a specific part number, and must be hard-mounted.

[TheHolyHades1]

Originally Posted by EricH

Just as a note: If I'm not mistaken, these would be located well downstream from the compressor, say on the other side of the storage tanks. This isn't the pressure relief valve, it's a regulator. The PRV has a specific part number, and must be hard-mounted.

Ah. I figured I missed something. Thanks!

[tr6scott]

Originally Posted by orangemoore

Does this even pass rule 66 G?

No.

Some manufactures offer optional outlet pressure ranges, but I do not see that on this cut sheet.

Should not have passed with >60 outlet pressure.
IMHO, not an inspector.

[rfolea]

Hi Guys,

The max pressure rating for this device is 145 psi.
This is sold under the NITRA label so I can't share the original manufacturers data sheet with you.
I'll put in a request to get the NITRA spec sheet updated.

Comments on posts:

(Jeff Pahl - Been Long time! How ya doing!)

#7: "And the spec sheet only says that it regulates from 15-120 PSI." It regulates between those values - the max rating is 145.

#12: R66G - This really only applies to the primary regulator which HAS to be the KOP regulator (and is limited to 5-50psi). These should only be used DOWNSTREAM of that. Just like all the other regulators we typically use. Yes, I know the rules don't explicitly say that - we are talking to FIRST about the wording of that rule because it doesn't make any sense as stated...

#13 "Is it worth using these type of fittings ..." Oh yeah ... Space savings, weight savings, mount them anywhere, totally worth it. And again - these would not be used as the primary regulator right up next to the compressor.

This IS a PRV type regulator (relieves excess downstream pressure)

And while we are at it ...

The original post only shows two of the parts offered as inline. There are a bunch more folks need to be aware of:

Pressure Indicators: (PMU14A, PMU14G) Green and Orange - Has a little pop-up indicator that pops up when the system has 30+ psi in it. An awesome way to tell if the system is pressurized at a glance

Shut Off Valves - 2 and 3-way shut off valves - the 3-way valves relieve downstream pressure so you can shut off a subsystem and release pressure at the same time. Very handy. (HVU14-2, HVU14-3)

These are also available in lockable versions.

Quick Exhaust Valves - Want to speed up you pneumatics? This is a great way to do it. Routes exhaust air directly to atmosphere.


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Either Chip McDaniel or myself (Rick Folea) will be happy to help you out.

[rfolea]

... Should have mentioned that all of these items are located here.

[Kevin Sevcik]

Originally Posted by rfolea

Quick Exhaust Valves - Want to speed up you pneumatics? This is a great way to do it. Routes exhaust air directly to atmosphere.

These don't pass R66, unless we ignore the parenthetical "(specifically "needle valves")". I wanted to use some last year and was shot down by the GDC:

Q34
Q.Is a quick release valve, such as the one sold by Bimba (part number 1BQEV), considered a flow control valve, and thus a legal pneumatic component per Rule 77 (F)?
A.Quick Exhaust Valves are not included on the list of permitted items in R77.

R77(F) is largely identical to this year's R66(F) except for this year's addition of "passive" and the parenthetical. So unless the GDC's interpretation has greatly changed, quick exhaust valves were illegal this year.

Mind you, I'd love if they were legal for the obvious speed increases. So if you're petitioning the GDC to update the regulator part of R66, you might want to add that as well.

[Conor Ryan]

Originally Posted by Kevin Sevcik

These don't pass R66, unless we ignore the parenthetical "(specifically "needle valves")". I wanted to use some last year and was shot down by the GDC:R77(F) is largely identical to this year's R66(F) except for this year's addition of "passive" and the parenthetical. So unless the GDC's interpretation has greatly changed, quick exhaust valves were illegal this year.

Mind you, I'd love if they were legal for the obvious speed increases. So if you're petitioning the GDC to update the regulator part of R66, you might want to add that as well.

I'm not so familiar with quick exhaust valves, why would they be ruled unsafe?

[Oblarg]

Originally Posted by Conor Ryan

I'm not so familiar with quick exhaust valves, why would they be ruled unsafe?

A good question that has never been adequately answered, especially given the fact that it's legal to just not put a fitting in one end of a dual-stroke cylinder and vent directly to atmosphere that way.

[rfolea]

Originally Posted by Oblarg

A good question that has never been adequately answered, especially given the fact that it's legal to just not put a fitting in one end of a dual-stroke cylinder and vent directly to atmosphere that way.

Some folks disallow quick exhaust valves because they are technically "Check Valves" (Only let air pass in one direction, other direction is vented) and anything that can keep a system pressurized (like a check valve) after the air has been vented to the atmosphere is illegal, since we don't want ANYTHING left pressurized when the system has been opened up, for obvious safety reasons.

The problem with this argument is the QUICK exhaust valves actually make the system SAFER in that they GUARANTEE the system won't be pressurized.

Yes, we are working on the wording of that one too ... Sometimes common sense HAS to win ...

BTW - all the solenoid valves folks use that have a center closed position are ALSO illegal under this rule (they can keep a system pressurized after venting), but no one seems to notice that ...

[Kevin Sevcik]

Originally Posted by rfolea

BTW - all the solenoid valves folks use that have a center closed position are ALSO illegal under this rule (they can keep a system pressurized after venting), but no one seems to notice that ...

Closed center solenoid valves would actually probably fall under R78(A):

Any pressure vent plug must be:
A. connected to the pneumatic circuit such that, when manually operated, it will vent to the atmosphere to relieve all stored pressure in a reasonable amount of time.

Whether they're legal or not depends on if you think the air inside them constitutes "stored" pressure, "working" pressure, stored pressure, or some other kind of pressure. The pneumatic rules use several different terms when talking about pressure on the robot, so I don't think it's clear if they want the the entire system at ~0 psig with the vent open, or if they just want the tanks at ~0 psig.

In other news, the pneumatics rules are kind of arcane and vague and could really use some revising to better clarify and enforce whatever the GDC's intent behind them is. There's some hint of an intent to limit actuator speeds and unintentional overpressure from external loads on cylinders, but it'd be better if they spelled that out up front.

[The Lucas]

Originally Posted by Conor Ryan

I'm not so familiar with quick exhaust valves, why would they be ruled unsafe?

FRC rules are not necessarily implying that they are unsafe. R66 is a prescriptive rule listing the only pneumatic components which are legal. If it doesn't fit in one of those categories then it is illegal. Check valves are also illegal according to the Q&A. My speculation is that FRC wants limit the types of valves to solenoid valves (ultimately controlled by the on the RIO firmware), relief valves (prevent over pressure on compressor) and pressure vent plug valves (each has to be capable of venting all pressure on their own, not in combination with other valves like quick exhaust valves) so that it is easy for inspectors to verify that the system is safe & under control. Probably the most time consuming part of the inspection process is verifying pneumatic operation (especially testing the setting of the relief valve) and verifying the operation and orientation of quick exhaust valves or check valves would only add to the time and complexity of inspection.

Originally Posted by rfolea

#12: R66G - This really only applies to the primary regulator which HAS to be the KOP regulator (and is limited to 5-50psi). These should only be used DOWNSTREAM of that. Just like all the other regulators we typically use. Yes, I know the rules don't explicitly say that - we are talking to FIRST about the wording of that rule because it doesn't make any sense as stated...

The primary regulator doesn't have to be the KOP Norgren one, the blue box under R71 recommends 2 different part numbers, but those are not the only ones that can be legally used. The Monnier data sheet has output data for over 60 PSI but it must be adjusted to no greater than 60 PSI on a robot.

Originally Posted by rfolea

Shut Off Valves - 2 and 3-way shut off valves - the 3-way valves relieve downstream pressure so you can shut off a subsystem and release pressure at the same time. Very handy. (HVU14-2, HVU14-3)

R66B requires pressure plug vent valves be functionally equivalent to the (2-way) KOP valves, so I am not sure 3-way valves would be meet that requirement (probably should ask next years Q&A, or try to get the rule changed for next year). I agree they would be useful (especially this year for removing cylinders to fit into transport configuration).

[GeeTwo]

Originally Posted by Dunngeon

you won't melt tubing on a competition bot because of the short run times

It depends entirely on how much air you need. If you're using air solely to shift gears, probably not. If every function other than drive is pneumatic, quite possibly. We blew out several hoses (with a crack like a .22) during practice for rebound rumble. We had a pneumatic climber, but we didn't even have the climber attached yet. We were just making adjustments to the Frisbee primer that required depressurizing the system. In filling up our (seven?) plastic tanks, we blew out the hose at the end nearest the compressor. The large quantity of air depressurizing through the rupture cooled the tubing back down, so it took us several swaps to figure out that it wasn't just defective tubing. This was followed by closer monitoring to figure out the actual cause. Our solution was to relocate as much of the brass as possible to before the first piece of tubing, and continued monitoring for swollen tubing.

[Dunngeon]

Originally Posted by GeeTwo

It depends entirely on how much air you need. If you're using air solely to shift gears, probably not. If every function other than drive is pneumatic, quite possibly. We blew out several hoses (with a crack like a .22) during practice for rebound rumble. We had a pneumatic climber, but we didn't even have the climber attached yet. We were just making adjustments to the Frisbee primer that required depressurizing the system. In filling up our (seven?) plastic tanks, we blew out the hose at the end nearest the compressor. The large quantity of air depressurizing through the rupture cooled the tubing back down, so it took us several swaps to figure out that it wasn't just defective tubing. This was followed by closer monitoring to figure out the actual cause. Our solution was to relocate as much of the brass as possible to before the first piece of tubing, and continued monitoring for swollen tubing.

Emphasis mine. I said Competition Bot. We use a different compressor that is rated for 100% duty on the practice bot, but use the VIAIR 90C on the competition bot for the obvious weight savings. Nearly our entire bot was pneumatic, and the 90C was capable to compressing for nearly 20 minutes straight before we ever had a blow out. (not that I recommend it)

On the practice bot, we use either a Thomas 215 or another who's name escapes me.

Also, if your tubing was blowing out from only filling 7 (assuming black Clippard?) tanks you may want to re-evaluate both the fittings and tubing you are using. I know in our case, we have melted the O-rings within the 1/4 pneumatic quick connects (but this is after 30+ minutes of running and the crappy FIRST Choice connectors)

Or add a fan.

We use Freelin-Wade tubing, and SMC pneumatic fittings.

[ToddF]

Mounting a KOP computer cooling fan blowing on the compressor head allows the small compressor to be run at 100 percent duty cycle. We have done all day demos with our 2014 bot, with pneumatic catapult, and the compressor barely gets warm. This year our air consumption is less, so we left off the fan. Just filling two tanks gets it scalding hot.

[GeeTwo]

Originally Posted by Dunngeon

Emphasis mine. I said Competition Bot.

We made the corrections during practice and did not have the problem during competition. For UA, our understanding (probably incorrect, as I recently learned from another thread) was that relieving the air pressure between matches was mandatory. As a result, we stressed the system more during competition than we did during pre-climb practices when we were actuating a single 3/4" diameter cylinder with about a 6" stroke.