# First post, new member…. Air chambers & new materials



## karlwithak.conley (Nov 26, 2021)

Air chambers are still required by some plumbing codes. Many experiments and studies have proven that they are very prone to water logging due to the air dissolving into the water. This makes them inoperable and forms a dead end in the potable water system. Neither is a good thing. With the popularity of PEX and the flexibility of the resin used to make the tubing plus proper design sizing lines to keep flow speeds under 5 feet per second, is there any logical reason to keep simple air chambers allowed?
Mechanical shock absorbers? I am OK with, as long as they can be accessed if they should ever fail. On copper or rigid plastic tubing they may be required, especially on washing machines and the like.
But PEX with its flexible tubing, as long as properly sized, what is the point?
How do other codes handle air chambers and shock absorbers. I am in Illinois.
I rather think many codes, Illinois included, should consider updates to take advantage of modern technologies.


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## skoronesa (Oct 27, 2015)

karlwithak.conley said:


> .................is there any logical reason to keep simple air chambers allowed?
> 
> Mechanical shock absorbers? I am OK with, as long as they can be accessed if they should ever fail. ..............



*Slow your roll bucky! No, simple air chambers should not be made illegal, nor should they be seen as a replacement for a mechanical shock absorber or miniature expansion tank. *I am always against outlawing things that can be handy in certain situations, even if they are not ok for most.

-Simple air chambers, aka dead ends of pipes, can be pretty useful in situations where the maintenance staff have their wits about them. If plumbed properly, all you need to do to recharge them is drain the line and refill.

-Mechanical and bladder shock absorbers frequently get covered with drywall or are otherwise never made accessible.

-Simple air chambers are great for a seasonal use building that is going to get drained every year anyway!

-Not all water qualities dissolve air at the same rate, where I am it takes quite a while to do so. We still have many old, bladderless well tanks in use here. I have pictures of well tanks older than you and I combined that have no air volume control.

A couple years ago we renovated a very large inn with a ballroom and pools that hosts weddings etc. In almost all of the public restrooms they have sloan valves. They also have a constant pressure pump controller set for just under the legal limit to help with flow issues in the older parts of the building. The ideal fix for those sloan valves would have been proper shock absorbers in the walls. Here's what transpired.

During demo our guy flushed a bunch of them and noticed the bit of water hammer, his suggestions to remedy this went unheard. Legally they weren't required to use shock absorbers under this AHJ and no one wanted to add the cost. When he repiped behind each fixture he used a tee instead of a 90 and ran an extra two feet up the wall with a cap making a simple air chamber. He also added boiler drains when he cut in new shut offs in the basement. The maintenance guy at this facility, once a year has a list and he exercises the valves and drains the lines with sloan valves to recharge the air chambers.


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## skoronesa (Oct 27, 2015)

That job was all sweat copper by the way, even though it was only ~5 years ago.


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## karlwithak.conley (Nov 26, 2021)

You rather made my point. There are seldom to never any provisions made or required by code to facilitate draining or recharging air in dead-end chambers. Homeowners would never be reliable to do so anyway. Yes, some very experienced building superintendents might be expected to have a preventive maintenance schedule to recharge dead-ends. I wish they all did. But they don’t. 
It is true that some water chemistry will be slower to absorb the air in dead-ends. Some gassy wells will actually recharge them if properly piped. But those are rare. And water chemistry with a lot of gas dissolved in it (that would be slow to pick up air from chambers) is generally acidic due to CO2 or other gases. This is of course avoided by all municipal water supply companies as detrimental to their piping. Some water plant use air stripper columns or additives to remove gases when present.
Some mechanical shock absorbers do get covered up by careless sheet rockers. But it is the duty of the plumber responsible to follow the code that should make sure that doesn’t happen. 
The story about the ballroom was good. The fellow showed understanding of the physics. But while he had the wall open to put in the dead-end that required draining and recharging, why did he not put in a mechanical of proper size? An access panel to get to it? And removed the need to do any periodic maintenance.
But the original question I asked remains. Will codes accept and change to adapt to new technologies like PEX?


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## Plumbus (Aug 4, 2008)

Code bodies do adapt, slowly. Take pex, for example. In some parts of Western Europe (EU) it has been legal since the '70's for domestic water. In the states, it wasn't legal until the '90's in some states and much later in others. I, for one, don't think that hesitancy was such a bad thing. Letting the other guy be the beta tester makes good sense to me. Another example of hesitancy is, at least in my area (specifically California, with a knock on effect across the continent), doesn't involve material, but rather pipe sizing. With all the state legislation restricting fixture gpm water flow, our pipe size tables are way oversized. Passing legislation without financing studies to gauge the effect of these laws is irresponsible. In a rational society, updating the work of Hunter and others, work done in some cases close to a century ago, would appear to be the horse and legislation based upon such studies, the cart.


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## karlwithak.conley (Nov 26, 2021)

You are very correct about the unfortunate results of manufacturers beta testing in the marketplace. Sometimes they are forced into it by well-meaning but short-sighted legislation. Remember the first and second generation 1.6 gif toilets? Some were little better than a hand dug latrine. But legislatures decreed that all toilets sold after a certain date must be 1.6 types. There were even some instances of toilets exported to Canada being smuggled back into the US to avoid using the 1.6 Clogmasters. Other debacles were caused by necessity. Victory weight cast iron, Orangeburg, Bundyweld tubing were all examples of materials used to ease wartime shortages. Codes could change very quickly if there is a political will and patriotic fervor driving it. And others were indeed just bad ideas. Polybutylene was one. Some of the rubber hose products for in-floor radiant heat were notorious failures as well. 
It is rather amazing that we still do not have a unified plumbing code for the nation. Water is wet and poop stinks and runs downhill from Maine to California. And Friday is still payday. If the money spent playing like the physics of flow are somehow unique in Chicago so that Cook County has to have its own code was instead spent testing and proving new technology we would be much better off. (Although such testing should be a cost borne by the maker or importer.)
An inconvenient truth is that some codes are not updated just to protect jobs and increase costs. Some will not change because a particular manufacturer is located in a state but a competing maker is not.
Plumbing systems perform their functions in accordance with scientific principles that change very little dependent on location. Political systems, well, do not.


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## skoronesa (Oct 27, 2015)

karlwithak.conley said:


> You rather made my point. There are seldom to never any provisions made or required by code to facilitate draining or recharging air in dead-end chambers. Homeowners would never be reliable to do so anyway. ....................
> 
> But while he had the wall open to put in the dead-end that required draining and recharging, why did he not put in a mechanical of proper size? An access panel to get to it? And removed the need to do any periodic maintenance.........
> 
> But the original question I asked remains. Will codes accept and change to adapt to new technologies like PEX?


We almost never use any shock absorbers in a residential home, even those larger than 10k sq ft. They shouldn't be needed when a system is sized properly. At most I would throw a couple on a washer box behind an access panel above. Unless you're running pressures over 60psi it's not a real concern.

I agree, homeowners should be considered useless.

He didn't add mechanical shock absorbers because he wasn't allowed. They weren't required by code and when he suggested them he was told no. Even the simple air chambers were only allowed because these couple bathrooms were a t/m remodel happening before the major renovations which were on bid.
They just don't build things like they used to. The Cold War-era buildings around here are vastly superior in construction being much easier to maintain. no one wants to waste 3' on a service hallway between back-to-back bathrooms.

In my opinion, one major change in relation to pex would be to require proper sizing based on actual flow rates instead of nominal pipe size. If this is already the case it's news to me. You shouldn't be relying on the expansion of pex piping to mitigate water hammer. Likewise you shouldn't rely on the restricted flow rates of low-consumption fixtures to keep velocities at a minimum, expecting that to mitigate water hammer.


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## skoronesa (Oct 27, 2015)

karlwithak.conley said:


> ............ Will codes accept and change to adapt to new technologies like PEX?


Everytime you pass a more restrictive code you reduce the discretionary power of the plumber in the field. Up to code is not always best practice. Unless you're building track houses, code is not one-size-fits-all.

Different areas of the country have different codes for very meaningful reasons. Many of those circumstances are unique to those areas of the country. I know it would seem like generic plumbing could work in any house, but that's only when they are new. Not everyone can always afford to bring a particular issue fully up to code.

Have you dealt much with well water issues? Oh the headaches that can arise. I have been in homes where the piston pump fed from the cistern is still tied in so the ancient homeowner can flip some valves and switches if the "New" well pump has an issue, and that "New" well pump just sucks from a "Spring fed pool" across the property.

I swear sometimes I expect to turn a corner in a root cellar and see salted ham hocks hanging from the joists which are trees.


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## karlwithak.conley (Nov 26, 2021)

skoronesa said:


> We almost never use any shock absorbers in a residential home, even those larger than 10k sq ft. They shouldn't be needed when a system is sized properly. At most I would throw a couple on a washer box behind an access panel above. Unless you're running pressures over 60psi it's not a real concern.
> 
> I agree, homeowners should be considered useless.
> 
> ...


Not using air chambers or shockstoppers when not required by code is a good practice, but not all codes allow not using them. Those unneeded requirements are what rankle me. But your statement about 60psi I question. Supply pressure has a proportional direct effect on the flow speed in pipe. Flow speed is the most sure method of causing water hammer. Reducing flow speed in any branch to less than 5 fps is the surest way to reduce or eliminate water hammer. So, in a respect, we do agree that sizing charts should be based on “real science”. Plumbers are smart cats. We can understand the different ID sizes for various types of piping. We can count up the ells and tees, multiply them into pipe length equivalents. And we can read and use charts for sizing based on real life performance instead of one-size-fits-all nominal charts.
It is that knowledge that certain material, like PEX, have qualities not found in other materials which allows my opinion that the resin’s inherent resilience makes it naturally resistant to water hammer. So why not take advantage of that quality? Also, yes, reduced flow rate fixtures will reduce flow speed in branch piping so I will expect the lowered flow rate to mitigate water hammer. I need not rely on it, it simply is so. 
Now understand, please! I am talking about “real-life” performance data for PEX-A using expansion fittings like Uponor. Full size ID fittings. Many of my opinions would NOT be supported by PEX-B or C using crimp or clamped fittings with reduced ID. B and C are not as flexible and do not have as much memory. Those material would have to prove to me by test that their sizing charts are correct and their other characteristics negate the need for a shock absorber requirement.


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## karlwithak.conley (Nov 26, 2021)

skoronesa said:


> Everytime you pass a more restrictive code you reduce the discretionary power of the plumber in the field. Up to code is not always best practice. Unless you're building track houses, code is not one-size-fits-all.
> 
> Different areas of the country have different codes for very meaningful reasons. Many of those circumstances are unique to those areas of the country. I know it would seem like generic plumbing could work in any house, but that's only when they are new. Not everyone can always afford to bring a particular issue fully up to code.
> 
> ...


Codes are restrictive by their very nature, but if written by professionals with the industry as the prime customer, I think they can be comprehensive. In Illinois there is a code weather line South of which 2” vent terminals are allowed, but North of the line they must be increased to 3” to prevent hoarfrost closure. Codes often dictate things like burying water service 12” below deepest recorded frost. Another variable.
I do feel for folks with financial challenges when dealing with code requirements, but that is why we have a process for code variance. It is a shame that the Laws of Economics often trump the Laws of Physics, but we know which was written first and by whom!
Yes, I have experience with wells, cistern and lake sources. I even took a scuba dive under the ice to free up a fouled submersible pump that would not raise. On the wall of my man cave I have a hand operated twin cylinder piston well pump, patented in 1910. The name of it? The Peter Pump, made in Kankakee, IL!


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## skoronesa (Oct 27, 2015)

karlwithak.conley said:


> ...........Also, yes, reduced flow rate fixtures will reduce flow speed in branch piping so I will expect the lowered flow rate to mitigate water hammer. I need not rely on it, it simply is so.
> ...............


Right, because no one would ever modify a plumbing fixture for more flow 🤣


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## skoronesa (Oct 27, 2015)

karlwithak.conley said:


> ...............But your statement about 60psi I question. Supply pressure has a proportional direct effect on the flow speed in pipe. Flow speed is the most sure method of causing water hammer. Reducing flow speed in any branch to less than 5 fps is the surest way to reduce or eliminate water hammer. .................


E=MC2

Like you said, pressure dictates velocity. Upping the pressure ups the flow speed exponentially, that's the square in the equation. By keeping your supply pressure lower you give yourself exponentially more "cushion" when things start to go wrong. Of course having a lower pressure will mean you need larger supply pipes, but having a larger volume(mass) doesn't have the same exponential multiplier as velocity.

I have found that houses with less than 60-65psi at the main have almost no issues with water hammer. Go up in pressure and you get a lot more problems, one of the reason code dictates a supply pressure of less than 80. Admittedly I don't usually suggest a PRV until they hit 100psi, assuming they aren't getting any water hammer.


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