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territorialmillworks

Advice on line pressure loss for new hammer

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Finished an air hammer with 2.5" X 10" cylinder and works well enough with the air compressor 100' away using a 3/8" hose. But obviously I'm missing a lot of potential with this set-up. My options are to move the compressor next to the shop and "share" a breaker with the mig welder in a maxed out subpanel box or saw cut 20' next to the expansion joint in the driveway and run 100' of 3/4 inch pipe. Honestly, both options suck but the last option is probably faster/easier...Anyone familiar with difference in friction loss between 3/8" and 3/4" on a 100' run......I'd like to make an 'informed decision'

"Failure never kept me from doing most anything once I set my mind to it"

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Got room in the shop for a decent size tank?
An accumulator tank set inside the shop may be an option.If you have even a smaller one handy(or can borrow one)you may want to plumb it in close to the hammer to see if it improves things.If it does then go looking for a big one and leave the digging and concrete cutting tools in the shed.

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I'm with Bob on the receiver tank near your hammer if you can't put the compressor closer.

On the pipe size, you would see a big difference in flow going from 3/8 to 3/4" line. It depends on the flow rate(CFM) of course. Assuming you are comparing schedule 40 pipe, the cross sectional area of the 3/4" is 2.8 times that of the 3/8".

You are talking about .03 cubic feet of compressed air per stroke(if I have my math right); how many strokes per minute do you expect?

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I don't have the room for a compressor indoors, nor do I want to listen to one run all day so I parked mine outside in a shipping container. I ran 1 inch 200 PSI jackhammer air hose (available at any industrial supply warehouse)from my compressor (7.5 HP 25 CFH @150PSI) 50 feet to my Big Blu 155 and a KA 75 (with no acumulator tank). I have had no starvation issues at all.

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Based upon my other hammer, I'm guessing a 150-175 BPM rate on the hammer. Now the idea of a storage tank is one that I hadn't considered. Potentially cheap and easy. I'll borrow back the smaller compressor from my son and see what happens. At work yesterday, we were topping off a helium balloon using 3,000 psi rated Parker hydraulic hose at an operating pressure of 600psi when it developed several pin holes. No one had every seen this before.It was pretty exciting (scary). No problem, we justed coupled up another length of hose only to have it rupture with about 20 pin holes. Checked the regulator pressure and discussed the fill characteristics of the balloon....robbed the hose from another system and it ruptured as well......boss goes to town and no one had any hose in stock....we went home after 4 hours....Maybe I can obtain one of the bad hoses, cut out the ruptured part and make a good 1" hose....me think I have a no cost alternative..........THX

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Pin holes in a 3000 rated hose running at 600, sounds like something else is going on. Was the rubber attacked by some lubricant in the air?

I once was at school's shop and using the air hammer for the first time. Well, either some other device was using all the air or the low set point was set too low. Trying to get a strike, I kept pressing the treadle down further and further and not even getting a full stroke. Suddenly the thing caught up and slammed my piece. I had fullering dies and the thing pinched off 1" round bar and spit the end out against the wall. That got the attention of the instructor.

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I was wondering if you are using quick connectors for the air hose. Most of the common connectors are 1/4 inch. If you went to a 1/2 hose with a 1/2 quick connector you would see a huge difference.

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I'll ditch the quick connects and plumb the hose directly to the compressor and hammer. Went on line and found that there is a hose specifically designed for helium and that closing the gate valve too quickly causes hose failure.....go figure. It didn't seem right that they would be using hydraulic hose for this application....

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Keith,

I built a hammer that needed 16 CFM at 120 PSI to run continuously but the compressor that ran my woodshop for the last 35 years (a big old Dayton two stage, 2 HP) only put out 7 CFM at 120 PSI and was 75 feet from the hammer. I ran ½ inch black pipe to the hammer. The hammer ran fine for about 30 seconds each cycle and then the pressure would drop below 120.

The Dayton runs the woodshop (which is my bread and butter) and I didn’t want to replace it and I didn’t have the room anywhere inside for a much larger compressor. I wanted to keep the cost down.

I bought a 3HP Harbor Freight compressor (11 CFM at 120 PSI) for under $400 and hung it on a bracket outside on the wall of the shop with a little shed roof over it to keep the rain off it. I ran a ½ inch pipe through the wall and connected it to the existing system with a ball valve. I set the pressure switch to come on at 120 and off at 150. The Dayton comes on at 140 and off at 165.

So here is how it works. The 60 gallon tank on the HF acts as a receiver for the Dayton and the pressure goes up to 165 in the entire system. When I use the hammer, I have 60 gallons of compressed air just a few foot away from the hammer and 80 gallons of air in the Dayton and the hammer runs fine. The Dayton can charge the entire system between heats and the HF doesn’t come on until the pressure drops to 120 which is not very often. When I’m not using the hammer, I turn off the ball valve to isolate the HF and its back to business as usual.

So I end up with 18 CFM to run the hammer on a 2 HP compressor and occasionally its 5 HP for a minute or two. Cheap air.

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Were the hoses you were using on the helium tank rated for helium? Helium's a very slippery molecure, mostly it's so small it's almost impossible to keep it in or out of wherever you want or don't want it. Even at moderate pressures helium will be driven right through most materials like air hose rubber and many plastics.

Happily helium is as nontoxic as it gets so unless you force all the oxygen out of a space it isn't going to hurt you. That is of course assuming you don't try something dumb like putting your finger over the end of the hose. It won't take much pressure to force helium through your skin. On the up side it won't do the kind of damage plain old air will.

Frosty the Lucky.

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Frosty, they were Parker hydraulic hose. You don't have to be an engineer to know that that there is a big difference in density. My guess is that hydraulic hose is cheaper and available locally while helium hose is expensive and special order. Evidently, it is common practice with balloonists to use hydraulic hose.

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