Water Treatment & Building Engineering
What is water treatment? Why do building engineers care about it? Is it really that important?
We’ll dive deep into water treatment and why we care about it throughout the post and yes, it really is that important.
It’s important as stationary engineers or boiler operators that we first, have a water treatment program, and second, actively monitor our water treatment. By actively monitor I mean frequent and routine sampling and testing and also using those results to determine actions or a plan of attack.
Purpose of Water Treatment for Building Engineering
As building engineers we add a variety of treatment chemicals to our systems, mainly water, to try and prevent conditions from popping up later. Conditions like scale formation, fouling, general corrosion can all start to begin as soon as water starts flowing.
Minerals that are suspended in water can get left behind and deposited especially in hot areas as well as in low flow areas. These minerals, like calcium, cause a build-up that slows flow down even more, sort of compounding the problem. These deposits also can lead to overheating in certain spots which then leads to failure.
Maintaining a water treatment program is easier and cheaper to maintain in the long run. Without one, your equipment efficiency will drop. How? Because scale can form on your heat transfer surfaces like inside your boilers. Scale reduces how well the boiler can transfer heat from the gases of combustion to the water it’s trying to boil.
So. Our boiler efficiency is first reduced due to our lack of water treatment. What does this mean?It means the boiler now has to work HARDER to produce the same amount of heated steam. And when a piece of equipment has to work harder for longer… it’s life expectancy decreases.
Water treatment is not crucial for just your precious boilers either tough guy. Or gal.
You should be sampling and testing water from your:
- Cooling towers or condenser water system.
- Chilled water.
- Hot and domestic water.
Heck, you should be testing the radiator fluid in your generators every 6 months to make sure it is mixed properly, in good condition, etc.
Since having a good water treatment program increases, or at the least minimizes loss of, equipment
efficiency, it also reduces down time and shut downs for maintenance or repairs. Less shut downs means less money lost.
We should also be sampling and analyzing so that we don’t waste our very expensive water treatment
chemicals. Sometimes systems can essentially be dumping these chemicals to a drain, it’s important that we recognize this asap.
How We Can Accomplish It
Main goals of a water treatment program would be to:
- Maximize chemical effectiveness.
- Maximize protection of piping and equipment.
- Minimize chemical usage.
First we monitor our systems. Sample and test system loops either as often as possible or as operation of the system dictates. Use this data to track changes and spot deficiencies. Compile it and send it to your water treatment engineer or representative for their input. Next, we monitor and record chemical consumption and usage. This is an easy way to identify issues such as over usage or waste.
- Conductivity – as the number of minerals present increases, conductivity increases.
- pH – higher the pH, the greater the chance for scale. The lower the pH, acidic which equals corrosion.
- Hardness – calcium and magnesium. These can leave actual deposits.
- Total dissolved solids (TDSS) – dissolved minerals that can lead to corrosion.
- Alkalinity – too high = scale, too low = corrosion.
Common Water Treatment Issues
Here is a list of common issues you’ll be trying to prevent with your awesome program that you can head up:
The accumulation of minerals that basically fall out of solution as the water is heated. You’ll find calcium, silica, and magnesium as the biggest culprits. Can’t picture scale? Think of the pot on the stove after you boiled water – that stuff left over.
We mentioned how scale reduces efficiency by reducing heat transfer. It does this because the minerals act as an insulator. Removing scale is a nightmare and expensive. Manage and prevent it before it becomes an issue.
Corrosion is the chemical process through which metals are eaten away, usually reacting with an impurity such as oxygen. Corrosion comes in many different forms like galvanic corrosion which occurs between two dissimilar metals in an electrolytic solution, pitting is another.
The boiler feed water is injected with something such as sodium sulfite which hunts down and eliminates oxygen. The two combine and form sodium sulfate which is a mushy sludge. The soft sludge is easy to get rid of through bottom boiler blow downs.
Factors that impact the rate of corrosion:
- Water pH
- Water temperature
- Water velocity
- Deposits in the system
- Biological growth
This is when corrosion occurs at high stress points where super alkaline solutions or minerals collect. Just look at the title, embrittlement, brittle. Caustic solution making the metal weak and brittle. This can lead to total metal fatigue and failure. Not good. Caustic embrittlement is one of the reasons we monitor total alkalinity in the boilers.
This is a condition that occurs on the surface of the boiler water. Sometimes there will be an impurity like oil present in the water. If there is enough oil, it will collect on the surface and form a film. This film increases the surface tension of the water and steam bubbles are unable to break through. Having this film reduces heat transfer and can lead to “hot spots” in the boiler or blisters.
Priming & Carryover
Priming is when big amounts of water make it out of the boiler and travel down the steam lines. That’s bad. Carryover is when small amounts of water get out into the steam lines. Also bad.
Both can be caused by having too high of a concentration of chemicals inside the boiler or by having a high surface tension like mentioned above.
Examples of Water Treatment Chemicals
Water Treatment Safety
It’s important to keep safety in mind since we are dealing with chemicals that could be caustic, acidic, bases, whatever.
Always wear ppe, or personal protective equipment, when working with or handling chemicals. At a minimum this should include safety goggles and a face shield for splashes and a rubber apron and gloves. Wearing eye protection and gloves is also recommended when drawing samples or testing.
Not only are the chemicals hazardous but think about it, the boiler water is not only full of the chemicals but it is also really, really hot.
Wherever a chemical or water treatment station is at, an emergency eye wash station should be nearby. Both for your eyes and perhaps even for a full shower. If you’re the water treatment engineer for your building or plant, I would try this simple test. See if you’re prepared. I would only do this test if someone was there watching you to make sure you didn’t get hurt.
Go to a chemical station and close your eyes. Pretend like you just got doused with a chemical, now you need to find the eye wash station or shower without being able to see. Close your eyes and see if you can find them. If you are in the boiler room with hot steam piping, don’t go fumbling around blindfolded. If there’s a chance you could step in a hole, don’t run the test. Better safe than sorry though, would you be able to save yourself?
Check This Out
How many of you have heard about coupons? No, not so you can get two cans of creamed corn for the price of one, but rather coupons and coupon racks for water treatment.
Out of the four places I’ve been a stationary engineer, only one of them had a coupon rack. Never had seen one before, haven’t seen one since. They are awesome and they really help and improve your water treatment efforts. Coupons provide real time results and measurements. Here’s how they work. Sort of.
Coupon racks are installed onto a system so that they receive a small portion of the entire flow, like the condenser water system. The racks hold coupons. Each coupon on the rack is made of a different metal.
The coupons are weighed before they are installed and then after a set amount of time, 30 days, 90 days, 180 days, they are removed. After removal, they are weighed again. The difference in weight gives us an estimated corrosion rate for that metal in that system.
For example, when we installed a copper coupon into the rack it weighed a perfect 1g. After 60 days, it
might weigh .75g, we lost .25 of a gram in 2 months.
The coupon needs to see full flow through the rack. Not enough flow could falsely indicate a high corrosion rate.
I am puzzled as to why more places don’t use coupon racks.
Here are a couple resources:
There should be no excuses now about not knowing much about water treatment.
This very long post covered why water treatment is crucial to us as building engineers and boiler operators. It also went over what exactly water treatment is, readings we need to pay attention to, and some of the why.
We are trying to prevent corrosion. Corrosion leads to unexpected shutdowns, equipment failures, and tons of extra work. By having and managing an effective water treatment program, you can reduce and minimize these consequences.
Be sure that you take away the important stuff, like what readings you should be taking. Readings like conductivity and pH. Pay close attention to your chemicals and how much your facility or building is
consuming. Does the chemical level never decrease? Is it being pumped into the system? Or is the entire barrel gone in a day, is it injecting too much?
Get a handle on your water treatment and it will pay dividends later when you don’t have to replace a bunch of piping.
Any comments, concerns, or questions? If so, please use the comment box below and let the site know! Until next time, a hui hou.