6.9 Pressure Sphere Test Rig

[wbrian63]

I looked for the original thread where I promised to deliver pictures of the setup I put together to test the "cracking" pressure of 6.9 pressure spheres.

Here are some pictures of the assembly:

Here's the pump - it's a 4-ton (8,000psi) model:


The gauge is attached to the pump, which is a bit inconvenient, as the pump is meant to sit on the floor and be foot-operated:


The "custom" adapter is nothing more than one of the hose-ends that's been grafted to a SAE (I think that's the right term) male tapered seat:


The bleeder screw:


And the "cup and valves" assembly.


The valve on the hose is to isolate the fluid in the hose and pump from the rest of the circuit - without it, there'd be now way to keep the pump from leaking out when not in use.

The hose is one made for this type of portable hydraulic pump, so it came with a one-way valve on the business end of the hose. It must be removed before attaching the hose to the valve, as it's design mates it with a variety of hydraulic devices that have special adapters that open the valve as the hose is attached. That obviously won't work with this setup.

My plan is to eventually mount the setup to a board to allow for easier operation. However, since the opportunities for use are "somewhat sparse", likely it will remain hanging on the bench pegboard where it's sat for the last year until tonight...

Use is fairly simple.

Take a sphere to be tested and determine first that it doesn't have a ruptured bladder. A pencil (eraser end) inserted into the large port on the end of the sphere should only go in about the distance of the bushing where the entrance pipe and and exit hose attach.

Attach the banjo bolt to the sphere, tighten it fully.

Put the bleeder screw in the hole where the line from the pump goes, but don't tighten the screw.

Open the valves below the cup and pour some ATF into the cup. No need to use expensive hydraulic oil for this test. Watch for bubbles to exit at the bleeder screw. When clean air-free ATF exits the bleeder screw, tighten it down.

Make sure there's still a small amount of ATF in the cup, then open the valve on the hose. Wait until no bubbles appear in the cup, add more ATF to preserve the volume present.

Close the valve below the cup.

Close the pressure valve on the pump, and watching the pressure gauge, actuate the lever on the pump. The pressure will jump almost immediately.

Where it stops making rapid progress indicates the "cracking" pressure - the point at which the pressure in the line and the pressure in the sphere behind the diaphragm are equal.

Make a note of the pressure reading and then open the pressure valve on the pump to allow the system to discharge.

DO NOT open the valve below the feeder cup before the system is fully vented, unless you want an ATF bath...

The "spec" #'s for the front spheres and the 5th sphere are 60bar (~900psi). The rears are less at 45bar (~675psi). Knowing this, and armed with a test kit, spheres too weak for duty in the front can be relegated to service in the rear.

Regards

[1980sdga]

Never fooled with SLS but that looks like a good setup. Bench testing can sure save you some time and trouble!

[WGB]

Very impressive Brian

Bill