Hydro testing fluid suggestions?

When you say PUMP ... what type pump we talking about ?

Are you using AIR to push fluid , or is pump compressing fluid ?

It's a "Porta-Power" hand pump (Chinese Porto-Power clone). All fluid.

Ok, so PUMP is meant to pump Hydraulic fluid ... but your asking if you can use WATER with an anti corrosive component then ? 


BEST way I see is incorporating a vessel ( Cylinder w/ floating piston ) between the pump and test apparatus.
This cylinder has a o-ring sealed piston able to float between ends, then a long coil spring inside compressing piston towards one end. This is the end where your pump is located.
As you force oil into cylinder the piston is moved towards the other end of cylinder.
Now on the other side of floating piston can be your water going into test fixture.

In this way you isolate fluids, no contamination.
If a failure happens all you loose is clean water.
Simply releasing bleed off on pump has spring retract piston and fluid returns to pump.
Rebleed the water side and go at it again & again ... 

Added content to above

Very good thinking, Scott. If I can't find a fluid for this, it may be my only option.

I could, if I choose, build a system that allows me to double (or any ratio) the power of this thing, right?

Pump side output can move more or less the floating piston with differing diameters.  But because floating piston of the chamber would have the same area either side of piston there would be no change in that regard within this part of system.

Also understand larger in diameter this chamber becomes, MORE fluid it takes to move displacing the water on otherside of the piston. As well beefier wall thickness etc needs to be.  For a near static minimal flow HP test fixture you don't need much displacement to take place.

Scott... Yeah, there is actually very little volume moved, when the system doesn't leak.

I'll eventually need a lot more power to test my 4.5K design to destruction, and am thinking that a 2:1 ratio would be fine, and given the tiny amount it would have to move, the booster wouldn't have to be very big.

I have to get through the 1.8K tests (FDPCP) first, and the rig will suffice for now (with the noted exception).

Bob... Looks like there will be more of my homework to check, as if my life depends on it. As soon as the Gen 1 thing is put to rest.

I already feel better, I hadn't thought about what to do when the gun failed.... and a cushion may save quite a few gauges. Good idea, as always. Thanks.

Eric,
Everybody has their favorite stuff, but this is the series of fittings I like to use in the shop for HPA and hydraulic test fixtures. 
http://www.mcmaster.com/#52215k621/=10pnuwb
1/8" O.D. annealed steel tubing. They are relatively inexpensive, and the ferrells  are only 88 cents each so you don't mind throwing away a section of line if it gets a kink in it.  They are only rated to 4000 psi working pressure, but I would guess they are highly derated to that 4000.  Also, you can them apart and put them back together with a 3/8 and 7/16 wrench and no having to worry about leaking pipe threads.  Just my 2 cents.
BTW, if someone were doing testing to 10,000 psi and expecting a failure and was adequately protected from the imminent "release", someone "might" use these 4k fittings in the hopes that their safety margin is above the 10k, which could be the case.  I know someone who used these to 10k on a one-usage-and-then-throw-away, type of deal, without issue.  We have to make our own decisions, though, and take responsibility for them.
Lloyd