VIAIR 250C-IG Compressor

[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.

[kmusa]

Originally Posted by ArtemusMaximus

And here is heat sink design I was working on. ...

Mounting fins to the motor case may work, but most of the heat is being generated in the cylinder, and not in the motor (Viair, for instance, specifically mentions not mounting the compressor upside down, because they find that more heat transfers from the cylinder to the motor.)

What we found is that just having a fan blow on the cylinder head kept the compressor temperature reasonable.

-Karlis

[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

[ArtemusMaximus]

Originally Posted by kmusa

Mounting fins to the motor case may work, but most of the heat is being generated in the cylinder, and not in the motor (Viair, for instance, specifically mentions not mounting the compressor upside down, because they find that more heat transfers from the cylinder to the motor.)

What we found is that just having a fan blow on the cylinder head kept the compressor temperature reasonable.

-Karlis

We also had fan blowing at the cylinder head. However we also found that our compressor was so overworked that motor was very hot as well. May be not hot enough to cause 1st degree burns, but I wasn't dumb enough to test that .
One of the reason for extra working time probably due to a minor pressure loss that we were unable to locate. I soped the heck out of it and didn't see any bubbles

As I looked at the design I posted it occurred to me that it is perhaps an overkill. I will put more thought to it and if I can make it simpler while still effective.

[cbale2000]

While we're on the topic of compressor cooling, here's a chart I made a few years back detailing the temperature difference a cooling fan makes on a VIAIR 90C air compressor...

https://docs.google.com/spreadsheet/ccc?key=0AqQx991m_YKGdEc3OV9NbG10YmluNjM2UFRhYV9Gb lE&usp=sharing

Hopefully someone finds this useful.

[ArtemusMaximus]

Originally Posted by cbale2000

While we're on the topic of compressor cooling, here's a chart I made a few years back detailing the temperature difference a cooling fan makes on a VIAIR 90C air compressor...

https://docs.google.com/spreadsheet/ccc?key=0AqQx991m_YKGdEc3OV9NbG10YmluNjM2UFRhYV9Gb lE&usp=sharing

Hopefully someone finds this useful.

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?

[MechEng83]

Originally Posted by cbale2000

While we're on the topic of compressor cooling, here's a chart I made a few years back detailing the temperature difference a cooling fan makes on a VIAIR 90C air compressor...

https://docs.google.com/spreadsheet/ccc?key=0AqQx991m_YKGdEc3OV9NbG10YmluNjM2UFRhYV9Gb lE&usp=sharing

Hopefully someone finds this useful.

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.

[wilsonmw04]

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.

fans are far more efficient at cooling on the "pushing" side as compared to the "pulling" side when it comes to open air applications. You would need a way to focus the air through the back end of the fan to make pulling air efficient (baffles or a closed in space).

[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 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

I found that chart somewhat confusing. I thought that 13.8V referring to last PSI value. If what you are saying is true and 13.8V applies to the whole table than evaluation need to be done for the VIAIR 250C-IG Compressor as well as it has same issue - 13.8V is also stated at the end of the table.

[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.

[ArtemusMaximus]

Originally Posted by cbale2000

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).



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.

Thanks again.
I wanted to add another thought. When I was looking to use bigger fan I realized that too big of a fan has a dead zone right under the center of the fan assembly. In my opinion it would be a good idea to place fan in such way that whatever needs to be cooled would be directly under the blades and not the center. I hope that make sense to everyone.