Al's 2016 Inspection Thread

[FrankJ]

I submitted the question on where the vent needs to be to Q & A. It is question Q933.

[Richard Wallace]

Originally Posted by FrankJ

I submitted the question on where the vent needs to be to Q & A. It is question Q933.

Thanks for doing that, Frank.

When I was a Lead RI, we had weekly conference calls with the Chief. Current LRIs I know tell me they still do that now. Several of them read CD frequently, so I expect that my Lead RI for this week's event will be able to give a ruling on vent valve requirements, should that question come up while inspecting a robot.

Before hearing from my LRI, my own opinion is the same as Richard Sisk's, based on my reading of R78 and Fig. 4-15. After I hear from my LRI, that could change.

[dradel]

Originally Posted by rsisk

I would rule it has to be on the high pressure side based on R78.



R78 If pneumatic COMPONENTS are used, the following items are required as part of the pneumatic

circuit and must be used in accordance with this section, as illustrated in Figure 4-15.



Figure 4-15 shows the dump valve on the high pressure side of the system.

I understand where you are coming from, but it is an example. My point is if the rule doesn't explicitly say it is open for interpretation, or opinions which leads to issues.

Similarly there is no official rule on where the main breaker has to be, and for the rule book to say "strongly recommend" doesn't mean has to be.

It becomes frustrating when others don't "feel" that the breaker or dump valve aren't in the correct place. If the rules aren't going to be explicit about such things then how can teams "fail" inspection? It's kind of like trying to say something isn't art.

[GeeTwo]

Originally Posted by dradel

It becomes frustrating when others don't "feel" that the breaker or dump valve aren't in the correct place. If the rules aren't going to be explicit about such things then how can teams "fail" inspection? It's kind of like trying to say something isn't art.

Most of the inspection rules, especially those that are left to interpretation, are about safety. Make it easy on yourself and your inspector - unless you have a very specific reason, just follow the recommendations. When you deviate from recommendations, have your "plan B" figured out beforehand (e.g. the recommended part already in the pit and a plan to install it). The example here is one - what's the big problem with just putting the vent plug on the high side?

[Jon Stratis]

Originally Posted by dradel

I understand where you are coming from, but it is an example. My point is if the rule doesn't explicitly say it is open for interpretation, or opinions which leads to issues.

Similarly there is no official rule on where the main breaker has to be, and for the rule book to say "strongly recommend" doesn't mean has to be.

It becomes frustrating when others don't "feel" that the breaker or dump valve aren't in the correct place. If the rules aren't going to be explicit about such things then how can teams "fail" inspection? It's kind of like trying to say something isn't art.

The rule on the main breaker isn't "strongly recommend".

R39 The 120A circuit breaker must be quickly accessible from the exterior of the ROBOT. This is the only 120A circuit breaker allowed on the ROBOT.

It's "must be". I will grant you that "quickly accessible" is a judgement call on the part of the inspector... But I can't think of a way to word such a rule as to remove judgement from the equation. All robots are designed differently, and a location that works on one won't work on another. The bottom line with this rule is how you want the event staff to handle your robot should it start smoking - pull out the fire extinguisher and give your electronics a dousing, or kill power quickly and safely? One way you'll likely be back on the field for your next match. The other is a huge mess.

Honestly, I've never had a problem getting a team to move their main breaker or vent plug valve to someplace more accessible. They all seem to understand the safety reasons (at least, the mentors do) for it and comply quickly and willingly.


Now, I have to ask... why is it such a big deal to have the vent plug valve on the low side? What do you get from that that other teams don't get by having theirs on the high side? Why not just hook up the pneumatics similar to figure 4-15 like everyone else to begin with? You seem to be very adamant about this, yet your robot has already been changed to have it on the high side...

[Alan Anderson]

Originally Posted by GeeTwo

...what's the big problem with just putting the vent plug on the high side?

It takes noticeably longer to move air from the low-pressure side to the high-pressure side through the recommended regulator than from high to low. If there is air stored at working pressure, putting the vent on that side lets the pressure be released faster.

[Al Skierkiewicz]

Originally Posted by dradel

My team couldn't pass inspection due to being on low side. When the students questioned this the inspector just walked away and wouldn't listen to reading of rules or reason.
Personally I don't think it matters one way or the other, but in the name of safety it is safer on the low side in my opinion.

What was "on the low side"? You have the right to call in the LRI at your event for a decision and they all have my contact info to ask about a ruling they are unsure of. If your pressure was low, was it at the output of the regulator or was the storage pressure too low? In the case of the working pressure being low, that is within the legal limits. A team can set the pressure to whatever they want as long as it does not exceed 60psi. However, many valves get flaky at lower pressure.
If the "storage pressure" was low, was the compressor turning off? If not, you had a significant leak.

[dradel]

Originally Posted by Jon Stratis

The rule on the main breaker isn't "strongly recommend".







It's "must be". I will grant you that "quickly accessible" is a judgement call on the part of the inspector... But I can't think of a way to word such a rule as to remove judgement from the equation. All robots are designed differently, and a location that works on one won't work on another. The bottom line with this rule is how you want the event staff to handle your robot should it start smoking - pull out the fire extinguisher and give your electronics a dousing, or kill power quickly and safely? One way you'll likely be back on the field for your next match. The other is a huge mess.



Honestly, I've never had a problem getting a team to move their main breaker or vent plug valve to someplace more accessible. They all seem to understand the safety reasons (at least, the mentors do) for it and comply quickly and willingly.





Now, I have to ask... why is it such a big deal to have the vent plug valve on the low side? What do you get from that that other teams don't get by having theirs on the high side? Why not just hook up the pneumatics similar to figure 4-15 like everyone else to begin with? You seem to be very adamant about this, yet your robot has already been changed to have it on the high side...

It isn't an overly big deal at this point. I was just wanting al to say it has to be on the high side, or it doesn't matter. In all reality it doesn't make a difference where the valve is located as long as the system is emptied in a timely fashion.

Now what's a timely fashion?? Our robot has two tanks, so it takes very very little time.

As for the breaker. I was referring to the blue box about the label saying breaker here.

[dradel]

Originally Posted by Al Skierkiewicz

What was "on the low side"? You have the right to call in the LRI at your event for a decision and they all have my contact info to ask about a ruling they are unsure of. If your pressure was low, was it at the output of the regulator or was the storage pressure too low? In the case of the working pressure being low, that is within the legal limits. A team can set the pressure to whatever they want as long as it does not exceed 60psi. However, many valves get flaky at lower pressure.
If the "storage pressure" was low, was the compressor turning off? If not, you had a significant leak.

The pressure release valve was on the low pressure side of the regulator in the system.

[GeeTwo]

Originally Posted by Al Skierkiewicz

What was "on the low side"?

Their vent plug was on the low pressure side of the regulator.

[dradel]

It just hit me that the point of it will vent faster if on the high pressure side doesn't exactly hold true. If teams were to have the accumulator tanks on the low side for whatever reason the stored air would have to flow back through the pressure regulator as well. I have seen regulators that only operate in one direction. That is to say air won't flow through from the regulated side to the supply side, which would prevent the system from being completely emptied.

[Jon Stratis]

Originally Posted by dradel

It just hit me that the point of it will vent faster if on the high pressure side doesn't exactly hold true. If teams were to have the accumulator tanks on the low side for whatever reason the stored air would have to flow back through the pressure regulator as well. I have seen regulators that only operate in one direction. That is to say air won't flow through from the regulated side to the supply side, which would prevent the system from being completely emptied.

The regulator is required to be relieving, per R82, for exactly that reason. When high pressure is released in this case, the low pressure side would be vented through the regulator.

[dradel]

Agreed. Was just bringing up the fact that some do not vent both ways. But the fact of the tanks being on the low side and having to vent back through the regulator and it "taking time" still applies.
My biggest reason for continuing this debate is so I can have something to show my students after the fact. I strive to not just teach them how parts fit, and or interact, but also how to question things when needed, and that if you ask several people the same question you will get several different views. Not saying mine is right, or wrong and the same for the others that have posted, but rather different ways of looking at it and the importance of being able to do so constructively.
I do thank you all for all your views and comments, our team is actually going to devote about a half hour to this topic and how to interact with the inspectors in a constructive manor. You all have provided me with more info and knowledge to pass along than most might realize.

[Richard Wallace]

Originally Posted by Jon Stratis

The regulator is required to be relieving, per R82, for exactly that reason. When high pressure is released in this case, the low pressure side would be vented through the regulator.

But the relieving regulator will stop relieving when it reaches the working pressure set point, correct?

[dradel]

That I have never tested. But I don't believe it will hold pressure on the working side like you thinking it may. Time for a test !!