Legal Solenoids

[Thomas Bayhi]

Is an SMC solenoid model NVF3130-6G-02T legal to use?

[apalrd]

<R72> In addition to the items included in the KOP, pneumatic system items specifically permitted on 2010 FRC ROBOTS include the following items. All included items must be “off the shelf” pneumatic devices rated by their manufacturers for pressure of at least 125psi, and used in their original, unaltered condition (except as required for assembly with other components).
...
C. Solenoid valves. All such valves must have a maximum ⅛” NPT port diameter, and a maximum Cv of 0.32 (if non-KOP valves are used, the team will be required to provide part documentation validating that the valves meet these constraints).
...

If it fits these rules, and uses 12v or 24v power (no other voltages are available to you), then yes you can use it.

[laxcompute]

Hmm. I looked up the documentation for that valve, to see if it would work for my team's purposes. From what I found in the documentation, all of the VF3_
30-__

-02 valves have a Cv higher than that 0.32 limit. The b value is 0.32 exactly, according to the documentation, but I don't know what that means.

[jamie_1930]

Originally Posted by Thomas Bayhi

Is an SMC solenoid model NVF3130-6G-02T legal to use?

Page 14
http://www.coastpneumatics.com/metri...ies_valves.pdf

From what I've gathered, you should double check, No you have a 1/4 NPT twice the maximum of 1/8 and everything in the 3000 series above the maximum Cv of 0.32

Also I am the last person who likes to say this, but I will for this occasion because helping you this time was a 15 minute ordeal. Read the rules do the research. Just go to google with the product number and go through the specification documents.

[JCharlton]

The Cv value refers to the effective resistance to air passing through. Higher Cv values let air through with less resistance (faster) and FIRST probably limits this for safety reasons, as well as to give a break to teams that can't afford specialty stuff.

You can do things like run two solenoids in parallel to halve the resistance of the valve. Also look at doubling long runs of pneumatic tube, that has a surprisingly high resistance.

Simple test is to pump the cylinder back and forth with your hands with and without the solenoid attached (just attach to the open solenoid port) to see how much it slows down the stroke. Then try with varying lengths of hose.

Good luck!

[Ether]

Originally Posted by JCharlton

.. Higher Cv values let air through with less resistance (faster) and FIRST probably limits this for safety reasons...

You can do things like run two solenoids in parallel to halve the resistance of the valve...

Not to argue, but if it's a safety issue, why is it OK to run two solenoids in parallel? Doesn't seem to make sense...


~

[TubaMorg]

There is no rule against placing solenoids in parallel. However, at some point the parallel paths must meet at a single point, thus nullifying any perceived gain in flow rate. Alternatively, the parallel paths would lead to different components, again nullifying any perceived gain in flow rate.

[Ether]

Originally Posted by TubaMorg

There is no rule against placing solenoids in parallel. However, at some point the parallel paths must meet at a single point, thus nullifying any perceived gain in flow rate...

I'm not sure I follow your argument. Does the "single point" where the parallel paths meet have to be 1/8" too? I thought the 1/8" applied only to the valves themselves...


~

[laxcompute]

But all of the tubing has to be the same diameter as the green tubing in the KOP, which is where the trouble is. I was planning on buying some nice big tubing to lower resistance, but noooooo. must. keep. rules. people. happy.

[JCharlton]

Originally Posted by TubaMorg

There is no rule against placing solenoids in parallel. However, at some point the parallel paths must meet at a single point, thus nullifying any perceived gain in flow rate. Alternatively, the parallel paths would lead to different components, again nullifying any perceived gain in flow rate.

Cv works like a resistor in an electrical circuit. By putting them in parallel you get the familiar

1/Rtot = 1/R1 + 1/R2

So the resistance to the flow of air through two solenoids is half that of just one.

The same goes for hoses. There's a lot of skin friction and turbulence going on in the hose, so even though it finally goes in to the same point you've reduced all that friction.

You've find a good explanation here:

http://www.hydraulicspneumatics.com/...se/21595/Issue

Give it a try. We did lots of this testing to make our catapult in 2008.

Good luck!

[Don Wright]

So...digging into the valve question a little further...

The checklist for the KOP says:

VUVG-L10-B52-T-M5-1P3-566458

The valve we ACTUALLY got (based on sticker on the side) was:

VUVG-L10-B52-T-M7-1P3

If you look in the catalog, the difference between the M5 and M7 are the fittings. Checking with the local rep, the M5 version listed in the KOP checklist has a delivery time mid-Feb. The M7 version (which we actually got in the kop) has immediate delivery...

Can anybody look in thier KOP and see which version you got (M7 or M5)?

I plan on posting a Q&A on the legality of the M7 version...

Thanks...

[Mark McLeod]

I've seen several M7 versions arrive in on Long Island KOPs.
Some from Manchester, others picked up at our local remote kickoff.