Need help with a Military Davey...

[mommystop]

My husband owns a concrete pumping business and uses Scuba tanks to blow out his hoss. We fill about 5 large tanks a week to do this. After spending more than 1500 over the last year getting our tanks filled, we decided to by our own compressor. We purchased a military davey style compressor with 3500psi and 15cfm (After getting advice on here to do so). Now I need to know if there is anything I need to do to modify it to fill the tanks. And if it's very technical, is there a manual, or any place on the web where it's outlined? I am not worried about Air quality as the air in the scuba tanks won't be for human consumption. My husband is extremely handy (He works on all our pumps, etc) but he feels a little out of his league as he's never worked on a compressor before. Thanks in advance.

 

[pescador775]

Plenty of Davey technical manuals and CD's on the web. Available at EBay. You need a fill whip which is a high pressure hose with yoke connector, air bleed and gauge. Available from many sources including Compressed Air Specialties. Speak to an engineer or technician on the phone. You may need to replace dessicant in the condensators if it is used but I would not say it is a major concern; however, should be attended to at some point. All compressors follow a similar plan. There is an engine or motor, a high pressure pump and a filtration system. The condensators (filters) are small tanks with drain cocks and they need to be closed during operation and opened (release hp air and water) after the last Scuba tank is filled. In addition to the basic system there are fail safe devices called relief valves. If you have the MC1, the final relief should be pre- set somewhere around 3500 psi. Read the book and understand the basic operation before running the machine. After a while it will become routine.
If any breathing air tanks are to be filled, make sure that the compressor intake is up wind of the engine exhaust. The intake is located on top of the high pressure pump. This contains an intake filter similar to the filters found on engine carburetors, etc. Replace or clean as needed. Make sure that the oil used in the hp pump is 30W compressor oil, not engine oil.

 

[pescador775]

Bargain Marge will fix you right up.
http://cgi.ebay.com/2MC1A-Manual-Da...2QQihZ020QQcategoryZ83044QQrdZ1QQcmdZViewItem
If I were in your husband's position, I would chuck the dinky scuba tanks and buy a 300 cu ft H tank rated for 3000 psi or higher. I would bolt the tank to my truck or whatever is convenient, run a regulator and long air line off it. That would require a different type of fill whip so think about it. The Davey will jam a scuba tank in about 3 minutes making the tank too hot to touch. Use a water barrel or similar. Aluminum tanks are easier to cool than steel but make sure their date of manufacture is post 1989. Better and safer.

 

[pescador775]

I looked through my files and located an operators manual for the Davey. I would guess the govt paid about $20,000 ea for those machines. Don't get excited over the complexity, these compressors are built with very logical and fail safe controls. For example, all those gauges: the high pressure pump operates with four stages (cylinders), much like a diesel engine. In addition to the final pressure gauge, there are gauges for each of the four stages. If ever there were a problem with the pump, these gauges would be used for trouble shooting the problem. They are like the gauges in your automobile, to check on things from time to time. These compressors have a clutch, like in your stick shift car. They also have gadgets like "pressure unloading" valves which are used to dump air pressure and make starting up easier on the machine. The operators manual includes all the diagrams, pictures, data and explanations to get you started. Govt manuals are extremely thorough. Good luck.

 

[pescador775]

Bargain Marge owns the business, Protecair. They sell all kinds of compressors including military surplus and have parts/manuals for the Davey. You might want to communicate your wishes directly. Assuming you bought a good unit and not a lemon, you will need an operators manual, not a shop manual; although the latter might come in handy some time, somewhere.

 

[mommystop]

Thanks for all the info. I will look into getting the manual and pass these on to my husband. We have Concrete Pumps that he does all the maintenance and repair on himself, so I am sure he will figure it out. I am curious about the heat issue of the current tanks we have. I don't think he would have counted on that. It sounds kind of Greek to me, but he will probably understand. Am I to understand that you should just place the tanks in a barrel of water to cool them off as you fill them? I didn't know if that was literal or what. How much are the 300 cu ft H Tanks? Where would you buy them at? Our local scuba store seems to be limited in knowledge and time. The Gov't auction listed the price on the Davey as $18k originally. It only has 190 hours on it, so I am hopeful that it's not a lemon. My husband is picking it up next week, so we shall soon see. For a Thousand Bucks, I hope we scored!

 

[pescador775]

190 hours is nothing for these military machines. Expect your compressor in good condition to last more than 3000 hours. That's enough scuba tanks to stretch 15 miles. Rapid filling of the scuba tank will cause it to heat up. Place the tank in a trash can full of water when filling. The scuba tank will fill rapidly, within 5 minutes. However, the compressor can be left running while the operator shuts off the fill whip valve, shuts the tank valve, bleeds pressure from the filling manifold, and hooks up the next tank. The H tank is a type of storage cylinder, like the big tanks you see at welding shops and gas supply houses across the country. Compressed air specialties has them, new, but maybe too expensive. They have used DOT air storage tanks for $265. You should be able to find locally. Oxygen tanks are hard to obtain because of rules which limit ownership. Don't mess with them. You need an inert gas tank or air tank. The tricky part is choosing a tank with the right valve. I believe the DOT air tank is best. The installed valve should be CGA 347. Whatever valve is installed the fill whip must fit. You will not need a water barrel for this tank. If I knew exactly what is being done with these air tanks I could offer more advice. If the large tank can be used while fixed in place to a vehicle or in a shed, then you should sell the scuba tanks and use the large storage tank. If you need portability you may be stuck with the scuba cylinders. It is not my nature to speak in parables. Same with the government. If the item was listed "F7" it is likely in very good shape.

 

[pescador775]

I guess he knows this, but the Davey's pintle hook is not suited for high speed towing. To retrieve the Davey, he probably would need a rollback with winch or a flat bed and a hoist. Be a good idea to double check the plan and ask somebody at the depot how customers remove and transport the items.