|Pressure tanks, which come in a variety of sizes, allow pumps to run for regulated periods and also offer some storage. Source: Wikimedia Commons|
Over the years I have written about many aspects of water well drilling and water systems. Some of these are drill rigs, pipe for well casing, pipe for drop pipe, pumps, well screens and other subjects. All of what I have written has been what I have experienced in a career of over 70 years if you include my years with my dad as his companion before I was old enough to be much of a helper. This article starts a subject on a component that is a very necessary part of almost any domestic or commercial water system, a pressure tank — sometimes referred to as a holding tank.
Now, for sure, there are some uses of pumped water that do not need a pressurized system: direct connection to an irrigation system and filling ponds, farm tanks, fruit cooling tanks and some others come to mind. I’m sure some of you readers know of uses where just water and not water under pressure is all that is needed. Just about every domestic system and most commercial systems, especially the small ones, do need water under pressure. For the system to operate properly, a pressure tank must be a part of that system.
The pressure tank, of course, does not create pressure. The pump, whatever the design, does that. But the tank allows the pump to run for regulated periods and also offers some storage. Water cannot be compressed to any degree at least at the pressures most systems work under. The air in a pressure tank, however, can, and that air makes what is called a hydro-pneumatic system work.
The first pressure tanks I remember seeing as a young boy going on jobs with my father were simple round, steel tanks and, generally, the steel was galvanized. In those days, the early 1940s, tanks were really heavily galvanized and I don’t remember changing many tanks due to corrosive failure. This was long before our environmental friends decided that zinc and lead and other heavy metals were killing people in record numbers. During World War II my dad even installed some black steel tanks. They were not as durable as their galvanized cousins, but the metal to coat them with was in short supply due to the war effort. They did not last as long as a galvanized tank but they worked and did the job; we even used one as the tank for an air compressor system in our shop.
Now, these tanks back in the day came in a rather wide assortment of sizes. There were 12- and 20-gallon tanks used mainly on jet pumps and small piston pumps. Then, moving up, there were 42-gallon tanks, one of conventional dimensions and another that was fairly short, which was called a “squat” type. These were followed by 80-gallon, 120-gallon, 220-gallon, 315-gallon and 525-gallon sizes. Of course there were larger tanks, starting with 1,000-gallon horizontal types and going up to about as big as one could imagine. But I don’t recall ever working on one over 1,500 gallons. Even the 525-gallon tank, which was rather rare around here, was 36 inches in diameter and 10 feet tall — just a bit impossible to get into the basement of most houses, especially if they had a 7-foot ceiling. In the days when stroke pumps of low capacity were quite popular, we did see a lot of the 120-, 220- and 315-gallon sizes, especially on dairy farms that used then, as now, lots of water.
Now, these tanks, no matter what their size, came with lots of tapings. A typical vertical-style tank would have 2 or 3 openings right at the bottom, another opening about a third of the way up, yet another opening about two-thirds of the way up and possibly a small-diameter opening near the top of the sidewall. And then, of course, they all had an opening right in the domed top with a plug installed as it came from the factory. If this opening leaked at all, the tank would quickly lose its compressed air and the owner, followed by the pump man, had a repair job.
When plumbed to a stroke pump (deep well), small-piston pump (shallow well) or a jet pump, the supply from the pump was piped into the opening about a third of the way up the tank. The water line going out, feeding whatever use the water was needed for, was plumbed as low on the tank as possible. If the tank had multiple low inlet/outlets, the extra outlets were either plugged or perhaps a drain valve was installed in them. The opening about two-thirds of the way up the tank was used for a so-called air control. On a stroke pump an air release device was threaded in at this point. The small-diameter hole near the tank was generally used for the pressure switch and perhaps a pressure gauge right near the switch.
On a jet pump the air control device was a diaphragm type often referred to as a Brady. I believe that was the name of the man who invented it. This, too, was installed two-thirds of the way up the tank. The air release used on the stroke pump was designed to release excess air that the pump supposedly provided with the water. This was done with a device like a so-called bicycle pump or one used to pump up a football or soccer ball. These little pumps and the air releases really didn’t work very well in southeast Michigan. I think our groundwater, while virtually always drinkable and safe right from the well, contained too many minerals that mucked up the works for both the air pump and the air release. The Brady-type control, which sounded like perfection in theory, rarely worked properly, and if the diaphragm in it failed on most pumps, the customer was OOW — or out of water.
That’s enough words for you readers to read for this time, so I will write more about tanks all the way to 2014 in future columns. As this is written in mid-April, what has been an absolute stinker of a winter refuses to quit. I am “proud” to report that we have set the all-time record for snowfall in this area, and yes, yesterday morning just as our grass showed the slightest tinge of green we got another 3 inches of snow. This morning it was 16 degrees Fahrenheit outside; we don’t need many more winters like this last one. However, we do not have the drought conditions that I understand a lot of you do. Until next time, as always, work hard, work safe and enjoy at least a few minutes of every day.