Can I use a hydraulic pump for air?

I am looking for a high pressure pump (3000-4500) psi.  I finally got the idea that I could use a pump like this: Hand Pump 
I think they have a built in reservoir but I think I could pump into it at around 100 psi from a pre-compressor.  Will this work or can it not pump air. Also, would it need oiled because it doesn't have the oil flowing through. 
Just so you know I wouldn't be pressuring a vessel to 4500 psi by hand, I would rig up a motor for this.

Re-design6 years ago
If you don't need oil free air you could use this for compressing air. These need oil to make a seal between piston and cylinder. But it's going to be very, very low capacity, meaning unless your containment vessel is smaller than an coke can you'll never get it filled.

If I needed a supply of air at 4,500 psi., I would build a trailer with several "bottles" that were tested to holde 4500 psi that were manifolded together and valved. Then pull the trailer to the nearest scuba shop or make a deal with a fire department to fill my bottles with air.
jj.inc (author)  Re-design6 years ago
Darn, thanks for telling me. I guess I am off to another cheep compressor alternative because the scuba thing wont work for my needs.