I’m hoping for advice from SMC users. We’ve never used pneumatics and are looking to purchase SMC valves and a manifold.
I’m leaning towards purchasing the SY3000 body ported valves (SY3120 and SY3220) and manifold with the “M” connector option because the manifold is smaller and lighter than the base mount manifold and the tubes and wires will protrude from the top of the assembly rather than the sides. I’m thinking that connections at the top of the assembly will be easier to access than ones from the side. I’m thinking how much easier it is to package and access connections to the cRIO in contrast to the Power Distribution module for example.
However, other CD posts I’ve seen refer to the base mounted style (SY3140 and SY3240).
What has your experience been and why would you prefer one style over the other?
Realize the rules for 2013 may not be the same for 2012…
The way the pneumatic rules are written with an odd Cv value & ports size restrictions makes it easier to conform to the rules while having maximum flow through the valve using by individual valves rather than a manifold. The robot inspectors are used to seeing individual valves. I try to make their job easy.
We’ve used manifolds for two years now. It does simplify the plumbing of the robot and a single manifold for several valves is much more compact than each valve having it’s own manifold.
In 2011 we used a 5 port manifold with Base-mounted valves. This means air was supplied in one end of the manifold and was directed out a port on the side of the manifold below each valve.
In 2012 we used a 5 port manifold with Body-ported valves. This means air was supplied in one end of the manifold and was directed out the top of each valve.
Both configurations save space over what you would normally end up with each valve having it’s own manifold. Both configurations also save some weight. Depending on where you plan on placing your manifold one configuration might work better than the other.
For 2012 our valves were from the SY3120 series. In 2011 we used SY3140 series.
Manifolds are perfectly legal for use in FRC per the last couple of years rules. YES you do have to work harder to find the proper cV value for your valve/manifold combination. YES you do need to have proper documentation proving they are legal. Inspectors have never had any trouble with manifolds in my experience and we’ve never even had to pull the specifications up.
For what it’s worth, we’ve used the SMC manifolds for years and if you have a LOT of valves they can make sense. I doubt they are lighter, though. The 4 and 8 valve manifolds are milled out of a solid block of aluminum and are pretty hefty.
Last year we only had three valves on our robot so I got the SY3240-6LO and SY3140-6LO valves that are body ported. The kids liked them a lot better. There are fewer fiddly little parts to mess with and they mount easily. I like them because they are easier for the new members to understand and are easier to re-purpose after the competition season.
The big lesson I’ve learned is that these little valves are delicate, expensive little watch-like devices. Don’t make the same mistake we did and store them in a box with the rest of your pneumatic junk. We’ve lost more valves to getting knocked around in that box than any other source.
I’ve never known an inspector to care about 1/8" NPT fitting rule as long as you can show that the valve meets FIRST specs and you don’t have valves with giant fittings (which probably means they don’t meet FIRST specs anyway.) After all some valves don’t even have threads, the fitting is integral with the valve. Your mileage may vary.
The 1/4" push-to-connect fittings is a different thing from the 1/8" port size. The 1/4" push-to-connect fitting is how you are actually going to connect to the valve or manifold. The 1/8" port size describes the size port that the fitting fits into. To be frank, this isn’t clearly laid out anywhere that I’ve found, this is simply my understanding of the valves after working with them for many years.
The reason a lot of say the manifold is better is because:
-One Central Spot for wiring
-One Central Spot for turning off and on solenoids manually.
-One airline to power all x amount of solenoids, this year we used 6. So it reduced the amount of air by 5 lines.
-Its not messy, as I don’t have to deal with solenoids in 6 or more spots.
-Also you can blank off spots your not using for around $2-4 bucks and add solenoids super easy. This year we thought we were using 6 solenoids, so we bought the 8 guy.
The common manifold requires longer runs to cylinders, but it has less fittings overall as there is a single input for all solenoids; that combined with the fact that an N-port manifold is far less space used than N single solenoids makes the layout a lot cleaner for most robots.
I like the idea behind using C[sub]v[/sub], but I don’t like the way the rules implement it (it’s under-specified), and I don’t like the way many valve manufacturers are vague about it (not specifying the test conditions, not specifying the ratings independently for different products in the same line, etc.).
The C[sub]v[/sub] ratings can be measured according to several standards, which are not necessarily equivalent. (A couple articles in Machine Design describe the controversy: see the accusation and the rebuttal.1)
1 This is actually the first time I’m seeing the rebuttal article, so I’m not going to reply with what I thought I was going to write about the merits of the different standards. This requires more research—but maybe someone else should take that project on, and report back the bottom line on the appropriateness of using different standards to find C[sub]v[/sub].
Cv does NOT change due to pressure or temperature, in fact the pressure and temperature are standardized (60’F and 1 PSI) as is the medium (water). Cv is a constant for a given valves geometry (orifice size, orifice geometry, mass flow diruption and eddies, etc) and can be used to calculate the mass flow rate through a valve.
Flow rate (mass flow) does change with pressure and temperature( and the medium flowing through the valve).
It’s been a while since I began this thread and I’m following up to let you know what we decided to buy and why. Our intention was to outfit our rookie team with pneumatics so we had hardware to learn with before the start of the upcoming season in January.
There’s a lot of detailed information available on SMC products and it took some effort to wade through and understand everything. A wide range of options are available so the purchaser can choose almost exactly what is needed - I like that.
I looked into buying Festo products since that is what has been provided in the KOP and we can be more certain that Festo components will pass inspection. From my novice vantage point, Festo seems to be the premier pneumatic valve supplier compared to SMC. Festo also looks to be just as configurable as SMC and you can mount Festo valves on a manifold - which we would like to to. However, Festo is a lot more expensive than SMC and harder to get.
I went through the process of contacting Festo with our team number and they said they would set me up so I could purchase directly from the Festo website, but Festo has not followed through with that so far.
…So I decided to buy SMC “body ported” valves because:
- output ports are on the top of the assembly for easy access
- electrical connnections also on the top of the assembly for easy access (option M)
- allows several valves to be mounted to manifold with a common input port
2 single solenoid valves, SY3120-6MZ-N7
2 double solenoid valves, SY3220-6MZ-N7
6 station body ported manifold, SS5Y3-20-06-00T
2 blanking plates, SY3000-26-9A (to plug the two vacant spots in the manifold)
6 one-meter-long wires with connectors, SY100-30-4A-10 (to avoid having to splice wires)
I ordered the parts from coastpneumatics.com. Some of the items were not in stock and had to be ordered from Japan. (I knew this when I placed the order.) I was quoted a six-week lead time to when the parts would arrive at Coast in CA. I placed the order on August 21 and received the last of it on September 7. The parts were shipped by UPS 3-day select even though I paid for UPS ground from CA to MI where we live. Great service from Coast Pneumatics…
Team member Nathan assembled our valves and manifold. We haven’t tried to use the valves yet - that will have to wait a little longer while we work on our software.