phoenix / utility hammer air usage

[lupiphile]

Hello all, I started a thread detailing(complaining) about some trouble I was having with my phoenix hammer,a little while back. After a extremely protracted correspondence with the hammer's maker(I actually got him to respond!), and some good advise from you all(should someone make john larson the saint of all fabricated utility hammers? we could just prey to him directly whenever something goes awry?) I've managed to get the hammer mostly right with the world. That is, excepting the speed thing. I've cleaned all valves and plumbing, installed a full port oiler, even went so far as to, run a new 3/4" air line with no right angled bends(pex, you're a godsend to a poor boy like me) and, though it's infinitely more snappy than ever it falls short of that elusive 200bpm mark. The new problem seems to be partly my compressor falling short. It's one of those 7.5hp ingerssol rand with an 80gal reciever. It claims 28cfm at 100 psi. I've been running my hammer at about 120 and been absolutely burying my compressor with one iron in the fire. My calculations for air usage go something like this, cylinder volume= 71.24 cu"(2.75"cylinder X 12" stroke), HOPEFULL bpm = 240, multiply them= 17097.3"cu, right? divide that by 1728 to get cubic feet, and you have 9.89. Any help or corrections would be much appreciated. It seems that even if my math is wildly off(more than likely) I still shouldn't be getting so under water with my air supply. I get it down to about 90 psi rather quickly. Well thanks everyone in advance.

[Dragons lair]

You need to be sainted for getting a response. I quit trying yrs ago and am close by(less than 10 miles) I did see him demo at blacksmiths depot
a while back(abana meeting) ya might give david a call at blacksmiths depot for speed info. Great folks there.
Ken

[Nakedanvil - Grant Sarver]

I admit I didn't go over your calculations, but you do seem to have missed that the hammer takes in two gulps with each blow (one up and one down). Way more to it than the straight volume calcs though. Because force = resistance, it will only take in what is required to raise the ram. Swept cylinder volume at full pressure never really occurs. Ask John. Easier working in "bar" (atmospheres) too. 28 CFM rated at what pressure, 90psi? lot less at 120. Compressor efficiency falls off fast at higher pressures.

[John Larson]

Like Grant, I have not reviewed your math. No matter, your compressor is adequate. I appreciate that you could use my past info. That's why I'm here. The speed of the hammer is directly related to the speed of the shuttle in the 5-port valve. I don't really remember my attempt to help you but the advice may have been to change the shuttle valve. Cleaning it may seem to be a fix, and I've done this more than a few times, but some valves don't work as they age like they did new. I just spent about 105 for a 5-port so in the cosmic scheme of things a replacement is cheap compared to time spent trying a cheap fix. Second, I don't think the hammer was ever up to that speed. It strokes too much IMHO and thereby has high air usage. It may be slick to mimic a self-contained hammer, but then maybe not when all the effects are understood. If your shuttle moves too slow then too much air flows into the cylinder each stroke, the stroke length increases, and the beats per minute fall. In addition to old age 5-port frictions, it is possible that the air flow to the ends of the shuttle from the roller (aka trigger) valve is too impeded. I use 1/4" id hose and I suspect Phoenix uses 1/8". It may not end up making a difference, but little hose barbs, clamps, and hose are cheap. BTW, check out the roller valve to see if it is exhibiting friction so that the spring loaded flapper (as I recall) is moving too much to actuate the roller valve. The cost may be about $80. (It too is a shuttle valve but it is lever actuated/spring return whereas your big 5-port valve is air actuated/air return as I recall.)

Essentially, the shuttle has to move snappily for the hammer to be snappy.

[Nakedanvil - Grant Sarver]

Thanks John! I will readily admit that John is, by far and away, the real expert in these matters. Really good, solid information that ONLY comes from the time and thought and experimenting someone like John has put in to it. I tended to use the 1/8 inch stuff on the theory that the larger hose took longer to pressurize. I will take it on faith that John is correct. And, yes, I should have posted that your compressor "should" be adequate. As John is saying (more of less) "it ain't how fast it goes, it's how much metal it moves"!

[lupiphile]

Like Grant, I have not reviewed your math. No matter, your compressor is adequate. I appreciate that you could use my past info. That's why I'm here. The speed of the hammer is directly related to the speed of the shuttle in the 5-port valve. I don't really remember my attempt to help you but the advice may have been to change the shuttle valve. Cleaning it may seem to be a fix, and I've done this more than a few times, but some valves don't work as they age like they did new. I just spent about 105 for a 5-port so in the cosmic scheme of things a replacement is cheap compared to time spent trying a cheap fix. Second, I don't think the hammer was ever up to that speed. It strokes too much IMHO and thereby has high air usage. It may be slick to mimic a self-contained hammer, but then maybe not when all the effects are understood. If your shuttle moves too slow then too much air flows into the cylinder each stroke, the stroke length increases, and the beats per minute fall. In addition to old age 5-port frictions, it is possible that the air flow to the ends of the shuttle from the roller (aka trigger) valve is too impeded. I use 1/4" id hose and I suspect Phoenix uses 1/8". It may not end up making a difference, but little hose barbs, clamps, and hose are cheap. BTW, check out the roller valve to see if it is exhibiting friction so that the spring loaded flapper (as I recall) is moving too much to actuate the roller valve. The cost may be about $80. (It too is a shuttle valve but it is lever actuated/spring return whereas your big 5-port valve is air actuated/air return as I recall.)

Essentially, the shuttle has to move snappily for the hammer to be snappy.

Thank you all for you're speedy responses.Ken Ive already sought the kayne's intervention. That in fact how I got this far. Tom has been very thorough in his emails, but has gotten fed up with my questions. He kindly wrote up this flow chart thing, the details of which I've gone over and nothing has gotten better.At this point it seems easier to field my questions toward you all.
Grant, everything you said makes sense, per usual. Thanks.I had to start somewhere.

John, the spring valve seems pretty well frictionless and the paddle that actuates it has plenty of spring tension, maybe the five-way is contributing. Any thoughts on why the hammer is using so much air? You're right about the stroke, I've been trying to figure a way to shorten it for a while. Any thoughts on adding a second spring valve? I recently had a chance to look at the inside of your hammers and I thought the valving was quite deft.My hammer's cylinder ports are 1/2" npt but connect to 3/8 id tubing . I know you're a big fan of both large ports and large cylinders, but do you think in my instance that it would make any significant difference, to solely replace the tubing with say 1/2" id stuff? And I still find my compressor's behavior vexing, I cleaned the air filter and gave it some oil, but I know not what else to do. Well thank you all, Matt

[Gayle Brooks]

Sorry to read about your troubles

We have the 75lb Bull hammers (older version of the phoenix) and run them at 100 psi which drops to 90 when the hammer is working. Though the only difference in setup we have is a 10hp air compressor, but I am at 8,400 feet as well. There is alot of intuition when we get ours calibrated, so I have not used any math.

Most issues that I have seen are the guides are way to tight causing the ram to get warm and constantly oiling (more friction causing more air to be used to push it so it cycles) and the the back arm from the treadle is not adjusted properly. This arm has a little weight that flips into a slot if that helps where I am talking about.

Dont know if this helps at all, just some of my experience. None the less hope it gets fixed, I do like these hammers.

[ciladog]

If you want to calculate the true cfm your compressor is putting out at a given pressure, this is how you do it.

The time it takes to pump the receiving tank of a know volume from a known starting pressure to a known ending pressure will measure the cfm using the Ideal Gas Law with isothermal compression where we ignore temperature (adds some error in the calculation) and change the pressure and the volume.

First, determine the tank size in cubic feet. You can take some measurements and calculate it to confirm say if you have a sixty gallon tank (divide the tank volume in gallons by 7.48 cu-ft/ gallon). So a sixty gallon tank contains 8.02 cubic feet.

Second, slowly bleed off pressure from your tank until the compressor cuts in, start a stopwatch, and note the pressure in the tank before any regulators. When the compressor cuts out, stop the watch and note the tank pressure. Subtract the starting pressure from the ending pressure and you get psi increase for a given period of time.

I’ll use a compressor I recently added to my system as an example. It has a 60 gallon tank and the label says it delivers 12.35 CFM at 100 psi. The cut in pressure was 120 psi and the cut out pressure was 148 psi and it took exactly 60 seconds (that was convenient). So I get a 28 psi rise in 60 seconds.

Next, convert the psi rise to atmospheres of pressure (1 atm=14.7 psi). So 28 psi/14.7=1.904 atm of pressure added in 60 seconds.

The rate air is being pumped into the tank is the pressure rise X the volume of the tank (8.02 cu-ft X 1.904 atm = 15.27 cubic feet) in 1 minute at 120psi (cut in pressure). The error range in these calculations could be minus 30% because we are not accounting for temperature rise or a gradual pressure rise so the range is somewhere around 11 CFM at 120 psi. To my surprise, the label on the compressor is probable pretty close to what it puts out.

Depending on the time it takes your compressor to cut out you will have to convert to minutes to get the CFM. Example: it takes 50 seconds, 60/50 X 15.27 cu-ft or if it takes 90 seconds, .666 X 15.27 cu-ft.

I hope this helps.

[lupiphile]

If you want to calculate the true cfm your compressor is putting out at a given pressure, this is how you do it.

The time it takes to pump the receiving tank of a know volume from a known starting pressure to a known ending pressure will measure the cfm using the Ideal Gas Law with isothermal compression where we ignore temperature (adds some error in the calculation) and change the pressure and the volume.

First, determine the tank size in cubic feet. You can take some measurements and calculate it to confirm say if you have a sixty gallon tank (divide the tank volume in gallons by 7.48 cu-ft/ gallon). So a sixty gallon tank contains 8.02 cubic feet.

Second, slowly bleed off pressure from your tank until the compressor cuts in, start a stopwatch, and note the pressure in the tank before any regulators. When the compressor cuts out, stop the watch and note the tank pressure. Subtract the starting pressure from the ending pressure and you get psi increase for a given period of time.

I’ll use a compressor I recently added to my system as an example. It has a 60 gallon tank and the label says it delivers 12.35 CFM at 100 psi. The cut in pressure was 120 psi and the cut out pressure was 148 psi and it took exactly 60 seconds (that was convenient). So I get a 28 psi rise in 60 seconds.

Next, convert the psi rise to atmospheres of pressure (1 atm=14.7 psi). So 28 psi/14.7=1.904 atm of pressure added in 60 seconds.

The rate air is being pumped into the tank is the pressure rise X the volume of the tank (8.02 cu-ft X 1.904 atm = 15.27 cubic feet) in 1 minute at 120psi (cut in pressure). The error range in these calculations could be minus 30% because we are not accounting for temperature rise or a gradual pressure rise so the range is somewhere around 11 CFM at 120 psi. To my surprise, the label on the compressor is probable pretty close to what it puts out.

Depending on the time it takes your compressor to cut out you will have to convert to minutes to get the CFM. Example: it takes 50 seconds, 60/50 X 15.27 cu-ft or if it takes 90 seconds, .666 X 15.27 cu-ft.

I hope this helps.

Well I figured out why Ive been short on air....after a frustrated morning of back and forth with ingersoll rand(them purporting that my whole head gasket, fingervalves and all we're junk)I decided to take the whole thing apart...again. I quickly found out that one of my transfer tubes betwixt stages( the one covered with radiant fins) had a stress crack.I deduced this after painstaking, scientific, and empiric research. It fell off. Ah ha!, says I. Seizing both the moment and the day, I shrewdly bent a piece of 3/4" copper to rough(like sandpaper) dimensions, scavenged some compression fittings, and away we go. The hammer has plenty of air, now. thank you all for your calculations. It still doesn't run fast enough though, much better, mind you, just not as fast as I'd like. I think you're entirely right, John. I think it never ran at that speed, though I still am considering replacing the five way valve, I'm just stick of spending money and time on this hammer, so maybe later on. I'd really like to shorten the stroke, But I just can't think of a good way to mount another limit switch/ roller trigger thing, and am very unclear as to how to plumb two triggers effectively. My only real experiance with utility hammer's is this one. Well thank you all for everything.

[John Larson]

Really glad you solved a lotta the problem. I've had the very same cracked tube problem and when I found it all I could do is laugh at myself for being so slow to check out an obvious thing. Ya know, behind the flywheel, outta sight, outta mind, AND I'm hard of hearing.

On the stroke length thing, I betcha you can study the lever system and determine a stroke shortening experiment. For example, on the Phoenix (not the Bull) the top cross arm may have more than one hole where the back rod connects. Using more distance between the back pivot and that rod pin should do it. Again, it has been a long time since I looked at a Phoenix. If another hole is there it will only take 10 minutes to try; 20 if you have to drill a hole or two.