VIAIR 250C-IG Compressor

[ArtemusMaximus]

Originally Posted by yash101

It is not the motor of the compressor that gets way too hot. The pump portion of the compressor is where the heat actually is generated, because you are concentrating the kinetic energy of air into a much smaller volume when you compress it. This causes a ton of heat to be expelled. To make the heat sink design more efficient, it would be wise to focus it's efforts on the small appendage that sticks out the end of the motor.

The reason why it seems as the motor gets quite hot is because the entire body is metal, so it conducts heat well. A ton of heat is generated at the actual compressor, making it extremely concentrated. Entropy finds conduction as one of the easiest way to spread out the heat, so it heats up the motor, which runs quite cool at that load.

If you were to build that heat sink, it would add more weight than benefit. The compressors shouldn't create so much heat within the two minutes of the game, that you would need to cool them with more than a small fan, even under a ~100% duty cycle!

As I noted previously, we mounted small fan on top of the cylinder heatsink and that seem kept it decently cool. However, during testing we had motor heat up so much that it was too hot to touch. Hence my original approach was start with motor. I also wanted to keep it as simple as possible that includes simplicity to manufacture it.
Looking again at the pictures I posted, I just realized that big fan over the Cylinder will not be efficient as it creates a dead-zone right where airflow is most important. I will try to think of something better.

[Al Skierkiewicz]

Originally Posted by yash101

The compressors shouldn't create so much heat within the two minutes of the game, that you would need to cool them with more than a small fan, even under a ~100% duty cycle!

Ah, but it does. Hence the exercise to keep it cool.

[ArtemusMaximus]

Originally Posted by Al Skierkiewicz

Ah, but it does. Hence the exercise to keep it cool.

and so does say the manufacturer sticker

[cbale2000]

Originally Posted by ArtemusMaximus

We found this compressor that by the looks of it meets requirement of FRC rule book for 2014 season.
http://www.viaircorp.com/250C-IG.html
I wanted to hear your guys input especially if I missed something in the rules.
Because it looks like far superior compressor comparing to VIAIR 90C while still under FRC's 1.05 CFM limitation.

Does anyone know how this compressor compares with the old KOP compressors as far as weight and fill rates?

[ArtemusMaximus]

Originally Posted by cbale2000

Does anyone know how this compressor compares with the old KOP compressors as far as weight and fill rates?

Yes, see the comparison table I compiled
http://www.chiefdelphi.com/forums/at...6&d=1399254659

[Al Skierkiewicz]

WildStang also used the new (Viair look alike) Thomas compressor. We liked it but it does not have a mounting flange or hardware. We considered that using any of the hardware on the compressor to mount it likely violated the "do not modify" rules so we made a custom bent aluminum tray for it. (Look for a change in the future.)
As pointed out, the Viair compressor comes with a stainless steel hose that is required by the manufacturer and so is required by the Q&A.

[Ben Martin]

Originally Posted by Al Skierkiewicz

WildStang also used the new (Viair look alike) Thomas compressor. We liked it but it does not have a mounting flange or hardware. We considered that using any of the hardware on the compressor to mount it likely violated the "do not modify" rules so we made a custom bent aluminum tray for it. (Look for a change in the future.)
As pointed out, the Viair compressor comes with a stainless steel hose that is required by the manufacturer and so is required by the Q&A.

This compressor? We used it this year. Great for weight savings and cfm is alright, but it really, really likes to heat up. We thought we'd give it a try after 254 used it last year.

[jimbo493]

The leader line actually looks quite useful. This year we had a few pneumatics leaks and didn't realize until someone pointed out the compressor has been running like nonstop. Eventually the hose off the compression had melted down a little and make the leak much bigger.

[wilsonmw04]

Originally Posted by Al Skierkiewicz

WildStang also used the new (Viair look alike) Thomas compressor. We liked it but it does not have a mounting flange or hardware. We considered that using any of the hardware on the compressor to mount it likely violated the "do not modify" rules so we made a custom bent aluminum tray for it. (Look for a change in the future.)
As pointed out, the Viair compressor comes with a stainless steel hose that is required by the manufacturer and so is required by the Q&A.

When we purchased our 215 Thomas compressor, it came with a large U-shaped bracket and a rubber mounting gasket. We replaced the bracket with large hose clamp. We placed the clamp around a frame member and tightened it enough to where a student couldn't rotate it in the rubber gasket. It never moved after mounting.

Link to mounting hardware pic:
https://drive.google.com/file/d/0Bwb...DNlVzZUWUNDdjQ

[kmusa]

Originally Posted by cbale2000

Does anyone know how this compressor compares with the old KOP compressors as far as weight and fill rates?

We had used the attached for comparisons earlier. (405 is the old Thomas KOP compressor, 415 was a similar model.)

Some comments:

1) The notable difference between the Viair 250C-IG and the Thomas 215 is duty cycle - 10% for the Thomas, 100% for the Viair. The weight is unfortunate, but it's a nice compressor.

2) In using the 90C, we used one of the KOP muffin fans blowing down over the cylinder - it helped a lot.

3) The 330C-IG on the chart is the bigger brother of the 250C-IG, but isn't within the FIRST limit.

4) When we asked the question, we were hoping that we would be allowed to use the braided hose (yes, it weighs more, but it's the piping right after the compressor that gets the most thermal abuse). Required was a surprise, but the net result was the same.

[ArtemusMaximus]

Here is Updated Comparison Table. Thrown CFM graph for better visuals.
Also added table with just Viair 90C & Thomas 215ADC38/12. Sort of to compare compressors that very close in weight and size category.
Judging from the spec sheets, it seems to me that the only reason to chose 215 over 90C is for slightly better endurance and better initial CFM performance up to 20 PSI.
I am pleased that Viair 250C-IG is legal and I think it's worth looking elsewhere on the bot to win those extra 4lbs that this compressor adds

[Mark Sheridan]

Originally Posted by ArtemusMaximus

Here is Updated Comparison Table. Thrown CFM graph for better visuals.
Also added table with just Viair 90C & Thomas 215ADC38/12. Sort of to compare compressors that very close in weight and size category.
Judging from the spec sheets, it seems to me that the only reason to chose 215 over 90C is for slightly better endurance and better initial CFM performance up to 20 PSI.
I am pleased that Viair 250C-IG is legal and I think it's worth looking elsewhere on the bot to win those extra 4lbs that this compressor adds

Do note the Viar 90C performance is at 13.8 volts. The Thomas 215ADC38/12 is quoted at 12 volts. Thus the 90C has better performance due to the higher supply voltage in its testing. It would be nice to get data points at 12 volts.

Anyone have a flowmeter handy? Maybe just time the two compressors to fill a known volume would be enough.

http://www.viaircorp.com/90C.html#tabs-2
http://www.cfpwarehouse.com/thomas/c...215adc3824.pdf

[Travis Covington]

Originally Posted by Mark Sheridan

Do note the Viar 90C performance is at 13.8 volts. The Thomas 215ADC38/12 is quoted at 12 volts. Thus the 90C has better performance due to the higher supply voltage in its testing. It would be nice to get data points at 12 volts.

Anyone have a flowmeter handy? Maybe just time the two compressors to fill a known volume would be enough.

http://www.viaircorp.com/90C.html#tabs-2
http://www.cfpwarehouse.com/thomas/c...215adc3824.pdf

This difference in the data sheets is critical - people should be sure to note that difference as the tables and spreadsheets that some have shared are significantly misleading without noting that. We use the 215 Thomas compressor because it edges out the Viair compressor when using comparable nominal voltage ratings, and is built to what we feel is a higher quality standard by a more widely known and reputable company.

[ArtemusMaximus]

Originally Posted by Travis Covington

This difference in the data sheets is critical - people should be sure to note that difference as the tables and spreadsheets that some have shared are significantly misleading without noting that. We use the 215 Thomas compressor because it edges out the Viair compressor when using comparable nominal voltage ratings, and is built to what we feel is a higher quality standard by a more widely known and reputable company.

I started this thread because I found very little information on VIAIR 250C-IG Compressor on FRC related sites beside the Q325 on FRC Q&A page.
I think by the way of this thread we are trying to clarify these details.

The only definitive way to be sure of the performance differences is to buy all of them and test. However, I don't think many teams have that luxury. I know our team doesn't - we have extremely low budget.

[cbale2000]

Originally Posted by ArtemusMaximus

Thanks cbale2000,
It was useful. It makes me want to do similar experiments.
What did you use to measure temperature and which part of the compressor you were checking for the temperature?

I used a multimeter with a temperature probe on it to get the reading. Don't know if its the most accurate but it seemed to work well for comparison at least. As far as where the probe was placed, I used the top of the heat sink since that's where the compressor seemed to get the hottest (and thus would show the greatest variation in the tests).

Originally Posted by MechEng83

Good info. Has anyone done a trial to compare fan direction? I wonder if drawing air up from the heat sink provides less or more cooling than blowing down.

Unfortunately in my test the fan direction was dictated by the mounting solution required for it on the robot. That said, however, on this years robot we were using an identical compressor and a slightly smaller fan (80mm or 100mm, not sure) with the fan mounted above the compressor and the compressor was cool to the touch immediately after coming off the field, so top mounting seems to be effective as well (Though the compressor on our robot this year may also not have been working as hard).

I do agree though that it might be worth another test to see what, if any, difference direction makes to the mounting position of the fan.