Ford Truck Enthusiasts Forums - My New Compressor....

I got what I believe is an excellent little “mid size” compressor. I believe Sears has discontinued this model (it was on clearance price) and possibly you could go get one yourself. It's a “5 hp., 30 gal. Cast Iron Craftsman “Professional”, Model # 19551 and puts out 6.0 s.c.f.m @ 90 psi.

"RUNNING VS. PEAK HORSEPOWER"
As I say, the one I got is a "5 hp. Cast Iron Professional" model, with a 30 gal. tank. It’s all black and looks like a 50% scale model of a full-sized, garage compressor. However, if you read the fine print, you find that it's 5 hp. at "peak" and 2 hp. at "running" or a "continous" output. They don't rate the horsepower honestly anymore. You must compare their relative s.c.f.m. @ 90 psi--ignore the higher s.c.f.m. ratings taken at 40 psi--what tool runs at 40 psi?

This single-stage, two cylinder compressor puts out 6.0 s.c.f.m. @ 90psi. We have an old 1972 DeVilbiss 2 hp., 2 cylinder compressor that puts out like 6.6 s.c.f.m @ 90psi. That machine is a two-stage compressor (a larger volume, low pressure cylinder compresses air first, for the second, smaller, high pressure cylinder to recompress) which I read are more efficient, but still.... See what I mean? Back in the day my new "5hp." compressor would (I believe) have been rated at it's continous power output (2hp.) and would have been marketed as a 2 hp. model. Not anymore. I'd like to know the continous power output of that "2hp." that other gentleman I mentioned was looking at—I’ll bet it was under ¾ of a hp!

I haven't run air tools with this one yet, but it's fast--fills the 30 gal. tank @ 135psi in about 3-4 minutes.

QUIET IS NICE
And the best part? It's QUIET. Things that make it quiet, IMHO:

1. Low RPM. This one is, I believe, 1950 rpm at the compressor. Think the motor is like 3,250 rpm.
2. Belt drive/separate motor. Don't know why, just seems these are quieter--less vibration amplification/transmission?
3. Big tank (for a less-than-fullsize-compressor)--cycles less often.
4. Cast Iron compressor "engine" block--just seems quieter than aluminum.
5. Oil in the compressor--to me, this is a must for longevity, but I also feel it muffles some sound.

This compressor can be wired to 240v, if you want.

TANK INTEGRITY
I read somewhere that tanks under a certain size (25 gal.? Not sure) don't have to be "certified", whatever that means. This compressor is "certified" by the "ASME" for 150 lbs. I presume this is a good thing.

THEY DON'T BUILD 'EM LIKE THEY USED TO...
This model is discontinued, I believe. It was $399.00 originally, but Sears put it down to $299 for "Clearance." Then I pointed out that it was a "display model" Bang! Another 30% off. Then the sales dummy lasered a flyer on the counter for another 10% off (apparently by mistake). Result: Paid approx. $185.00 for a $400.00 compressor.

Felt so good about it, I went back and bought a second one for my buddy, for $210.00. It was another day, (this month) and I didn't get the 10% off--but, whatever. Still a great buy.

The model # of this compressor is 19551, but if you don't list it in the following manner, no one at Sears will tell you it ever existed. Use model #: 875.195510--don't ask me why. All I know is no one at the store nor the corp. offices could find it under “19551” but a clerk got somebody to look it up under the longer number, above, which appears in the manual.

DON'T BE FOOLED BY:
A) Sear's sneaky trick of assigning a numerical "compressor rating" to their compressors. I noticed these numbers are always one or two numerals HIGHER than the advertised horsepower (which, as dicussed, is not the continous or "running" h.p. but the "peak hp."). My compressor does not have one of this hokey "ratings" numbers.

B) Sear's replacement of the model 19551 with some other model that also says "Proffessional" on it, is also 30 gal., is also black, and looks similar, except it is an integral design, i.e., no separate motor and compressor head, so no belt drive. And guess what? No OIL, either. And they sell this model that I believe replaces my 5 hp. as a "6 hp.," but when you read the fine print, it's CFM is LESS than my 5 hp’s CFM! It's 5.1 s.c.f.m. vs. my model's 6.0 s.c.f.m. And of course, even though it puts out about 15% less air, it costs more--lists for $439. vs. the original price of $399. for the "5 hp." model 19551 I bought.... So Sear's new model is "More Money, Less Air." It's got a higher hp. number (6 hp. instead of 5 hp.) but less cfm. Hmmmm.... less air, more money...and--more noise? The 6 hp. is the integral type (motor and comp. together, i.e., no belt), and I believe those integral designs are much noisier. I think they may turn faster than the belt drive models....

C)High cfm's listed as "Displacement". I don't know what this means, but my manual lists the "displacement" of my compressor as "9 cfm" but again, the cfm @ 90 psi is only 6.0.

D)Sear's "Recommendations" of what tools a given compressor will run. I'm talking about those lists of air tools, printed right on those compressors that are "blessed" with Sear's "rating" numbers, discussed above. Not all air tools are the same! I saw a comparison of pneumatic "Dual Action" sanders, like what are called "DA's" in bodyshops. And their cfm's ranged from about 7 to 28 cfm! Check your specific tools air requirements. With a consumption range of 7 - 28 cfm, for a DA, how can Sear's possibly make meaningful, arbitrary numberical "ratings" and recommendations? Funnily enough, the model 19551 lacks one of those goofy lists of tools the machine is supposed to be able to power. And as I said, it lacks the arbitrary rating number, (with the funny "star" symbol after it) whereas it’s replacment lists a rating of 6 or 7.

As I say, I suspect my cast iron, oil filled 5 hp. model has been replaced by the "6hp." model I described above. As was noted elsewhere, Sears continues it's downward spiral....

And I would NEVER buy an “oil-less” compressor. I can’t see how that’s a good idea, unless the application your using it for demands zero oil contamination in the air. And the way Sears and other retailers advertise these things like it’s a product benefit just astounds me! Does anyone know why they do this, i.e., boldly advertise on the side of the machine: “OIL-LESS” ?

After I found my compressor, I found a good article on them in a magazine called "Fine Homebuilding & Fine Woodworking/Taunton's 2004 TOOL GUIDE." On p. 82 is an article called "Buying Your Shop's First Compressor". On p. 84 they discuss "midsize" compressors, which it turns out are the same class as the ones discussed above. They picture a black Craftsman "Professional" that is NOT my model 19551, as it's showing an integral design, and mine is, again, sep. motor and compressor.

DUTY CYCLE
The above article discussed "duty cycle" and it stated that "small and midsize machines shouldn't exceed 50%". Elsewhere I read (I believe) that duty cycles is defined as "how many minutes out of every 30 min. period the compressor is running." The article mentioned above states "Large machines can run 100% of the time, known as the duty cycle, but small and midsize machines shouldn't exceed 50%." Elsewhere I read that a 100% duty cycle means, oddly enough, that the machine can run 30 minutes out of 30 minutes without damage.

WHAT'S IT ALL MEAN?
Find the air sander, ratchet, die grinder, impact wrench, shears, hammer and paint gun you want to run. Now identify all of their cfm needs. How often and hard will you use the ones with the highest consumptions? Now determine which of those tools you will want to run more than 15 min. out of every 30 min. (That is, if you're contemplating a "mid size" compressor costing from $299. - 450., with a 50% duty cycle). If you have tools which you need to run for continuous periods, and they consume more than, say 3.0 s.c.f.m., (i.e., half of a mid size compressor's approx. 5-6.0 cfm @ 90 psi) then you may be looking at a large compressor. The danger of exceeding the duty cycle limitations, I believe, is overheating of the compressor itself, thereby shortening it's life. I plan to use a number of tools, but I know I will have to remember to “cool it” to a 50% duty cycle level, which is okay for what I’m doing. I have an old monster compressor I will get going as soon as one of you comes up with a used, 5 hp., 240v, single-phase compressor-duty motor for me….

This new compressor doesn't list any duty cycle, on it or in the manual, but I'm assuming it's no higher than 50%, per the above article. I won't even attempt to ask Sears if there's a duty cycle rating, as they couldn't even tell me what oil to put in it! The manual specifies various SAE wts., (10, 20 or 30 wt., depending upon temperature) and cautions against "additives" but doesn't come right out and say "Use Non-detergent oil!" But I did anyway.

I would run, not walk, to my nearest Sears, and see if the elusive, discontinued Model 19551 is still hanging around. When I asked, they found one more in the store room and, as I said, I bought that one for my buddy.

This one is big, (190lbs) and surprisingly quiet. It has big, sturdy, solid rubber tires/wheels, so that you will never need to replace dry rotted tires. The padded handle and rubber-footed "foot" tube make it manageble on the stairs, with two people. And you might get it for the same price as one of those little compressors you can pick up with one hand, that make more noise than air.... I think Sears has discontinued a real gem, but that's just MHO.

If anyone has this model, or goes out and gets one, I'd like to know your impressions of it.

Good luck!