Using pre-charged accumulators

[Peter Matteson]

A question on pneumatics for some one who may have encountered this before:

If you pre-charge the accumulators and leave the compressor off the bot, are you required to have the compressor PSV (pressure relief valve) on the bot as validation you don't exceed 120psi?

<R95> makes me think you don't but I wanted to confirm as I don't have the Q&A password yet.

Reason for this, as a devious engineer without a PSV it would be easy to overcharge my accumulators and carrier a greater volume of air (at my working pressure, not storage pressure). I know it shouldn't be done but if I can think of a way to circumvent this easily so can many others.

Pete

[KenWittlief]

I think you have answered your own question.

Leaving the compressor off the robot is your option. This is no option to leave the primary pressure valve off. the primary side pressure valve with the gauge is required.

And I think if you showed up at a regional and tried to charge your tank with anything other than the FIRST supplied compressor, you would be swarmed by nearby mentors, judges and inspectors!

(the FIRST supplied compressor will not put out more than 120PSI max).

[Peter Matteson]

Ken,
The reason I ask is R95 only says I must have the pressure gages to show "working" and "stored" air pressure, and an accessible pressure vent valve to manually relieve the stored pressure. Making the gages read inacurately can be done, and the relief valve in asked for is the parker ball valve that comes with the kit. If I used my manual bicycle pump or car tire compresser I could easily exceed 120 without people noticing as they would think I'm adjusting tire pressue if they even saw me.

I don't want to do something sneaky it just seems to me like a simple rule requiring the pressure relief valve be mounted on the robot when the compressor isn't would prevent me from thinking of things like this.

[Justin Stiltner]

Isnt it in the rules that the energy that is stored in the penumatic system may only come from the FIRST supplied compressor, which is itsself limited to 120psi.

[Peter Matteson]

Originally Posted by Justin Stiltner

Isnt it in the rules that the energy that is stored in the penumatic system may only come from the FIRST supplied compressor, which is itsself limited to 120psi.

Not per <R02> the rule you are refering to. There is no defined source for the pressureized air.

Also for those of you who think I'm approaching this from a lawyering side that is far from what I'm doing. I'm looking at this as engineer who frequently designs pressurized systems to "ASME/ANSI B31.1 Power Piping Code" and "B31.3 Process Piping Code" and has to make sure other requirements for the ASME/ANSI Boiler and Pressure Vessel Code" (B&PVC). In said codes a pressure relief valve or rupture disc would be required on the storage tank to prevent over pressurization as a safety device. I was looking through the rules on this as we debated on the compressor and noticed what I see as a total miss by FIRST in not requiring a pressure relief device. I can think of many reasons and ways the 120psi could be unintentionally violated without having a safety relief and I think it should be rectified.

[DarkJedi613]

But there is in a different rule: <R96>

R96 - Pneumatic Storage
Teams are not allowed to remove or adjust the 125-psi set relief valve attached to the compressor.
You may only use the Thomas Industries compressor and Clippard Instruments air storage tanks provided in
the Kit to compress and store air on the robot. You may not use extraneous lengths of pneumatic tubing to
increase the storage capacity of the air storage system.

[Peter Matteson]

Originally Posted by DarkJedi613

But there is in a different rule: <R96>

Thank-you that makes me feel better I missed a word or 2 the last several times time I read that.

[dlavery]

There are several incorrect statements about the rules that really need to be addressed before anyone goes off and bases some bad decisions on them.

Originally Posted by Dzdconfusd

If I used my manual bicycle pump or car tire compresser I could easily exceed 120 without people noticing as they would think I'm adjusting tire pressue if they even saw me.

Originally Posted by Dzdconfusd

Not per <R02> the rule you are refering to. There is no defined source for the pressureized air.

That is incorrect. Rule <R02> states: "Energy used by FIRST Robotics Competition robots, (i.e., stored at the start of a match), may only come from the following sources: ... Compressed air stored in the pneumatic system, but only supplied by the compressor included in the kit, and stored at a maximum pressure of 120 PSI in no more than two Clippard Instruments tanks." It is also a violation of Rule <R96>, as has already been noted.

Originally Posted by Dzdconfusd

Making the gages read inaccurately can be done, and the relief valve in asked for is the parker ball valve that comes with the kit.

Modification of the gauges, or any other pneumatic components, is expressly prohibited by Rule <R94>.

Originally Posted by Dzdconfusd

As a devious engineer without a PSV it would be easy to overcharge my accumulators and carrier a greater volume of air (at my working pressure, not storage pressure).

To do so would be a direct violation of Rule <R02>, Rule <R94> and Rule <R98>. Yes, it is possible that you could knowingly circumvent the rules make it appear that the system was legal during inspection. Some might call that "devious engineering". I call it "blatant cheating."

Originally Posted by Dzdconfusd

I don't want to do something sneaky it just seems to me like a simple rule requiring the pressure relief valve be mounted on the robot when the compressor isn't would prevent me from thinking of things like this.

I'm sorry if this seems overly harsh, but the tone of the above messages makes it appear that you are explicitly seeking out ways to cheat. It is one thing to say, "I may make a mistake and accidentally violate a rule I don't understand." But it is another thing entirely to say "I will alter the gauges to give false readings that will make it appear that I am within the rules when I know I am not." Rules already exist to prevent exactly the sort of actions being discussed. All you have to do is read them and follow them.

Yes, FIRST could write even more rules to make it harder to cheat - but why should they? The community of teams gave very explicit feedback to FIRST for several years, asking them to reduce the number of rules and size of the rulebook. In return, teams committed to making a good faith effort to understand both the wording and the intent of the rules that were written, and to abide by them. It is not incumbent upon FIRST to write an onerous tome to document and prevent every conceivable situation that a team could create to circumvent the intent of the existing rules. It is the responsibility of the teams to read the rules that are already there, and follow them without resorting to devious workarounds that are specifically intended to violate the spirit and intent of the competition.

-dave

[DarkJedi613]

Originally Posted by Dzdconfusd

Ken,
The reason I ask is R95 only says I must have the pressure gages to show "working" and "stored" air pressure, and an accessible pressure vent valve to manually relieve the stored pressure. Making the gages read inacurately can be done, and the relief valve in asked for is the parker ball valve that comes with the kit. If I used my manual bicycle pump or car tire compresser I could easily exceed 120 without people noticing as they would think I'm adjusting tire pressue if they even saw me.

I don't want to do something sneaky it just seems to me like a simple rule requiring the pressure relief valve be mounted on the robot when the compressor isn't would prevent me from thinking of things like this.

I'm not quite sure what you're asking, but it seems like you're implying that you're going to add more pressure than the legal allowed limit to your system, which would be against the rules. As well as making the gauges inaccurate.

I remember a quote from last year that was something to the effect of "we're engineers, not lawyers." Just play by the rules, don't try to interpret them to your benefit. In other words your problem is in the line "if I can think of a way to circumvent this easily so can many others." Do not try to circumvent it - it undermines the entire concept of FIRST.