I bought this hydrostatic pressure tester from Amazon and used it to burst a 7 gallon (26.5 L) aluminum air tank I bought on sale from Harbor Freight. I thought the aluminum air tank might make a good LOX and fuel tank.
I selected this hydrostatic tester because of the price and it has its own reservoir (I don’t always have access to a hose spigot). My only complaint is that it came with a flimsy and suspect pressure gage; I replaced the stock gage with a nice, liquid-filled one and I haven’t had any other issues. I used flexible aluminum tubing to connect the tester and vessel because it is rated to high pressure, it can be coiled for storage, and is *much* cheaper than hydraulic hose.
The tank burst at 580 psi (40 bar) in the HAZ of the longitudinal weld. I was careful about getting all of the air out of the line and tank; the actual “burst” was rather anticlimactic. The tank diameter is 10.05” (25.53 cm) and the thickness is 0.095” (2.42 mm); this gives an ultimate strength of 30,679 psi (211.5 MPa). 
Amazon has a few 3, 5, and 7 gallon aluminum air tanks with NPT ports welded to them and the vendor advertises a 600 psi burst pressure.
The hydrostatic pressure tester is also handy for calibrating pressure transducers. Here it is calibrating a 250 psi transducer I bought on eBay:
