Thomas Compressor?

Somehow I managed to misplace all my links of where to get the large tan Thomas compressor that is used in FIRST. We tried the little Viair compressor and it just isn’t enough.
Can someone get me the part/model number and where to purchase the larger one?

Here’s the part number and link

Remember that R68 limits the CFM from any compressor used. May need to take a look at you design to require less air.

**R68 **Compressed air on the ROBOT must be provided by one and only one compressor. Compressor specifications may not
exceed nominal 12VDC, 1.05 cfm flow rate.


Looking at the specs from both compressors, the new Vaiar compressor actually has a .08cfm higher flow rate.

Thomas Compressor Information:
Viair Compressor Information:

The issue with that Viair compressor is the 9% duty cycle. It gets very hot and can be burned out if you aren’t careful. Running it constant for 2:15 during a match may seem like it’s not much, but when you add in pre-match charging and charging while testing in the pit, you will regularly exceed the 9% duty cycle and keep that thing blisteringly hot. The Thomas compressor is better at that and can run for much longer continuously.

As an alternative, Viair does make another compressor (250C-IG) that’s legal and has a 100% duty cycle. It’s part of their industrial grade line, and is rated at 0.88 CFM, although it has better performance at all other pressures than the Viair linked above.

The low duty cycle of the Viair compressor can be “fixed” easily, just put a big cooling fan near it, blowing air over the compressor whenever the robot is powered up.

Also, be sure to compare CFM specs at different pressures. Flow at 60 PSI is probably the most important spec.

I can not see any good reason to use the Thomas compressor, lower flow rate and higher wieght than the 090 series Viar. The Thomas is also only rated for 100psi which means that it is slow to finish the refill cycle as it is asked to provide 115psi before it shuts off. Yes it has a higher thermal mass which is a blessing and a curse. It will take longer to reach a critical temp but it will also take longer to cool down.

If the low duty cycle of the Viair 090 series compressor is an issue then the “Industrial Grade” 250c is the way to go. Note the 090 series compressor is rated for 3 minute of continuous use and is then in need of a 30 minute rest period so well within the normal FRC qualifying match useage. Now elimination rounds is a different story. As Mr Forbes mentioned fan cooling will keep temps down during a match and allow it to return to ambient temp quicker if kept running between matches.

In addition as Mr Forbes noted the flow rate at 0psi is not what you should be looking at. The important spec is time to refill from 85psi to 115psi. Unfortunately they don’t list that specific pressure range but you can still use the time to fill at the various pressure ranges and same tank size to compare the FRC legal compressors.

090c, 092c, 095c share these fill ratings.


Note with a 1 gallon tank the 090 series takes 30 sec to fill from 85 to 105 while the 250c takes 20 sec for the same fill.

At 60psi the 090 series will flow .53cfm vs .65cfm for the 250c IG.

This sells for more than $400, how is/has this been legal to use on a robot?

Per R9 part B, KOP items are exempt from the cost limitation. The glossary defines the Kit of Parts as the collection of items on any kit of parts checklist. As an example, see page 23 of the 2010 kit of parts checklist. The Thomas compressor has been in the Kit of Parts in the past, so it’s on a checklist and thus exempt from the cost requirements.