Hydraulic Ram Pump

Step 6 Piece by Piece (Pressure Chamber)

Now you need to put together the pressure chamber. Gather up your big pipe section, cap, adapter, bike tube, and bike pump. Using the pump, partially inflate the bike tube. Don't pump it up all the way, just enough that the tube is squishy. We need the air in the pressure chamber to act like a spring.

The bike tube prevents the pressure chamber from becoming waterlogged during operation. Air dissolves into water. It does so more readily at high pressure. (This is related to how commercially produced soft drinks are carbonated) The bike tube sequesters some of the air from ever contacting the water (in theory), and prevents all of the air from being carried out of the pressure chamber.

Stuff the bike tube down into the big pipe, a la image two. After this, cement on both ends, and clamp that sucker up. Once that's dried up, go ahead and glue this whole assembly to the pipe coming from the main tee.

Note on possible improvements / modifications:
Some may choose to omit the bike tube, and just drain the pump out every once in a while. That's totally possible. It's also possible to either mount a schrader valve onto the end cap of the pressure chamber to recharge it. Whatever suits your fancy, but this setup worked fine for me so far.

Comments

[magickaldan]

Or if you want to get fancier I'd use a Hot Water Expansion Tank from the local plumbing store. It has a valve on top for recharging and comes with a good rubber diaphragm.

[kenputer]

Just put a small tire tube with about 15 pounds pressure in the stand pipe for expansion. kenputer

[habolooby]

Very good point. That would work great, and it basically comes down to budget considerations.