Letter Re: Making Good Use of the Hissing Well

Mr. Rawles,
A s a distributor of oil and gas parts, it warmed my heart to read R.J.’s article. I would note a couple of things, however. First, when you reduce the pressure of gas you also reduce its temperature. In the aforementioned case, that pressure reduction would drop the temperature by around 10 degrees F. Ordinarily this isn’t a problem, but in the winter an already-cold regulator could seize or internal parts could break. With higher pressures, the problem becomes much more significant.

To solve this problem, most installers would use two regulators with some pipe between them. Each pressure drop is then made a little more gently and the gas has time to reclaim some ambient heat from the intervening pipe (which is often artificially heated) before hitting the next regulator.

Also, when using a safety relief valve, please buy a valve intended to pop 25% or more above your normal operating pressure range. (i.e., don’t operate at 150 psi and install a relief valve set to pop at 165). While it might work, it’s more likely the valve will never re-seat after the first pop. – Z.M.