I wanted to relay this information to other teams who may be using this part on their robot. During our inspection this morning, our inspector questioned the use of a 4 port aluminum SMC solenoid manifold on our robot, and whether this part had a working pressure capability of 125PSI.
I wanted to bring this to other teams attention to let them know about this issue during inspection so that they can be aware of the potential problem that can be made during inspection through the inclusion of a part on your robot which can be purchased from a FIRST authorized vendor using KOP voucher funds.
The real kicker, was that many other teams were using the exact same part had readily passed through inspection without even a question as to this “offending” part. Instead, our inspector would not let the issue pass, he would not approve the robot without a specification sheet from the vendor or otherwise be proven that an aluminum manifold would be capable of operating at 125psi even though the part was located on the low pressure side of the pnuematics system.
I wanted to pass this along as a word of warning to other teams who utilize this part. We missed 3.5 hours of practice this morning due to this issue, don’t let this happen to your team.
I believe that this part ( or any part not rated for 125 PSI) becomes legal if used on regulated pressure with the addition of a pressure relief valve set to less than the part’s rating. See R78 (D). The rule specifies solenoids, but I would think that the manifold would fall under the same rule.
We are using an SMC manifold and valves - not the same model sold by Vex, but the same series. We weren’t questioned by the inspector at either of our events, but we did have the SMC documentation with us and we had a second pressure relief value mounted on the manifold set to 100 psi.
The biggest problem I had with the “inspection” was that 12 other teams using the same part were passed through inspection without even a thought as to the part, however we were saddled with 3.5 hours of delay.
I’m more upset about the “selective” enforcement of inspection and the level of inspection, this was out 2nd regional event, had we known this part would be a problem we would have used another part or added a second pressure relief valve.
I agree with Eric. The LRI or even another inspector maybe familiar with the part and know that it is legal or not. You’re well within your right to ask for the Lead robot inspector.
Did you try asking another team for a specification sheet on that part?
Our team was told the actuator on our robot was illegal due to it actually being a motor, but we were still allowed to play practice matches because all you needed was a prelim-inspection, did it stop your team from practicing?
As others have stated, in any situation like this, you need to immediately ask, with the utmost Gracious Professionalism, for a ruling from the Lead Robot Inspector at the event.
And then please keep in mind that the ruling of the LRI is the “Last Word” on the subject at that event. I’ve had teams go off and try to get the Regional Director, Planning Committee members, etc, to try to overrule me on technical issues.
R78(D) only provides an exception for solenoid valves. ALL other parts MUST meet the 125 PSI requirement.
Maybe Vex could put some spec sheets on their pneumatics product page. That would make it more likely that teams will have this documentation when an inspector asks for it. Teams should expect that whenever they use a non-KoP pneumatic item.
We did talk with the LRI, however, since the part was “questioned” during inspection, he could not override the inspector. When it was mentioned that the part was used on robots already inspected and passed there was no response. The LRI even contacted the head inspector on the east coast for FIRST.
Overall the LRI and many other inspectors tried to help us in every way and were also a little perturbed that the one inspector would accept that the part was commonly used.
We did ask other teams if they had the documentation for the part, no other team using the part had the documentation, in fact, they became worried that they too would be flagged.
We were finally able to resolve the problem, thank you Vex for your help.
I am sorry you had some problem with this part. I have received a call or two on the legality of this part over the season. At Champs they will be considered legal.
I should mention that I was inspecting at SVR, but wasn’t the LRI or the inspector described above (though I did notice and speak to someone from 766 about this issue prior to their initial inspection).
The fundamental test of legality depends on the working pressure rating of the pneumatic device. The rule isn’t clear on the distinction between manifold and valve, but the manufacturer’s documentation (not attached, because I don’t know which version is most authoritative) implies that manifolds are included in the rating by picturing them alongside the table of specifications, with valves installed.
The relevant rules are R76 and R78:
Of particular note, the requirement in R76 applies to every pneumatic component, except those excepted by R78-D. Valves from the KOP (including FIRST Choice) can be permitted via R78-A (in which case they must meet R76, i.e. 125 lb/in2), or by R76-D (i.e. 125 lb/in2 or a relief valve). This means that—in the absence of a supplemental relief valve—every solenoid valve must be rated by its manufacturer for a maximum working pressure of 125 lb/in2. (FIRST did issue a Q&A that could be read in a manner that would give a different impression—but teams have to assume that the rules take precedence.)
The inspector was right to inform you of the violation, based upon the printed rating on the SMC SY-series valve you were using (0.7 MPa = 102 lb/in2). (The Festo VUVG-series valves used by other teams were rated at 8 bar = 116 lb/in2.) The burden of proof is upon the team to justify a higher rating, based on documentation. Appeal to the LRI is also allowed, and in this case, extenuating circumstances caused the LRI to rule that you (and everyone else) could use the valves.
In discussing this with the LRI, mitigating factors included the fact that FIRST had permitted these valves in the past, that the documentation was not clear on the definition of the pressure ratings contained therein (were they the limits of function, or the onset of failure?), that they were available as FIRST Choice parts (or via PDVs in the KOP, which isn’t exactly the same thing), and that there was no credible safety hazard.
After the LRI made his ruling, I documented 30 robots (of 59 at the event) that had valves bearing pressure ratings less than 125 lb/in2—almost all were the SMC or Festo valves mentioned above. I did not verify which robots were carrying the requisite relief valve, but didn’t see any additional relief valves on the robots I inspected in detail. Spare parts had only one relief valve to give, and that was best retained in case someone needed to protect their 120 lb/in2 system.
We were also in contact with IFI, who verified that they had conducted their own tests and were willing to warrant that the valves would be safe up to 0.9 MPa = 131 lb/in2 with a safety factor of 2.0. SMC also gave IFI a vague assurance about the working pressure rating, but because of several inconsistencies in SMC’s product naming scheme and their published documentation (according to IFI, who heard this from SMC, the newer SYJ-series valves are printed with model numbers in the SY-series—so there are two distinct but very similar product lines with the same SY-series model numbers), it’s not possible to conclusively establish the valves’ performance limits from the datasheets that a team could present at inspection.
Given the rules, and the other aspects of this situation, in my (unofficial) opinion, this should be viewed as special permission to operate without the mandatory safety device, rather than a declaration that these valves are legal on their own (alternatively, they can be legal with the relief valve). I’m comfortable with that from a safety perspective, because these valves are operated at a nominal system pressure of 60 lb/in2 or less, and even if overpressurized (e.g. by mechanical compression of an actuator), they will fail in very boring ways.
Note also that the rules only refer to a manufacturer’s rating (as opposed to a vendor’s)—this isn’t fair to IFI, because their documentation and efforts to test the valves are not officially recognized by FIRST. I’d therefore consider the use of vendor’s data to be another special dispensation.
The most viable long-term solution would involve FIRST improving the pneumatic constraints to tolerate this sort of issue more gracefully.
Aside: These valves don’t have great information on C[sub]v[/sub] either—the flow conditions and pressure drop are not indicated. Nevertheless, the SY3xxx series valves have C[sub]v[/sub] < 0.32, according to the SMC datasheets.