Bellows system vs. RV for thermal protection

[Bill3752]

Anyone ever looked at installing a bellows system to protect liquid filled piping instead of a RV? I am thinking this might have use if the liquid must be relieved to a vent system (i.e. the vent piping system cost would be substantial).

How about daisy chaining RVs at higher set pressures into piping operated at lower pressures?

Any ideas?

 

[TD2K]

Most of the places I work hate bellows because of the corrosion and resulting monitoring/inspection issues. They are usually a last option to address piping stress problems, doubt my clients would agree to use them for a thermal expansion issue though it's an interesting idea. Something akin to a pulsation damper on a plunger style PD pump might be more acceptable and would give similar protection.

 

[don1980]

By "bellows" I assume your talking about a canister with an internal diaphragm - same as a pulsation dampener. Yes, I've used those for protecting piping from liquid thermal expansion. They're just as effective as a vapor pocket withing the line. These are off-the-shelf devices. One name that comes to mind is Sentry. You can fine them on the internet.

A "daisy chain" of PSVs is another way to solve the problem. That usually requires using pilot operated valves, except for the final one, because the backpressure is too high for a balanced PSV.