We use clever design and parts like bearings to prolong the life of our mechanical equipment, but that’s not enough to save them indefinitely. Even if the immediate friction of metal on metal doesn’t kill something, there are other forces at work that will. It’s only a matter of time before something gives out in a big way.
Friction is STILL the Enemy
Bearings let us reduce the friction between spinning parts, that way we don’t have metal grinding on metal inside motors, valves, vents, or anything else mechanical. That’s not where the friction ends though. Friction is literally everywhere. Whenever two materials touch, there will be friction, including between the air and water against an object. This is destructive. Air and water seem soft and safe to us, but they’re actually capable of being extremely destructive over time.
This is most evident in pumps. The impellers spin and push the water around, creating movement and pressure. A new impeller will have precise, ‘teeth’, shrouds, that work direct the water like the blades of a fan. Over time however, the smallest imperfections will be worn into massive design failures. These shrouds will be worn down until they don’t trap, grab, and push water around anymore. They won’t hold up to pressure anymore.
Overtime, the water is grabbing bits and pieces of the metal itself and just carrying it away. Any weaker parts of the pump will be eaten and removed. This occurs anywhere piping and water is involved. At scale, chemical treatment is needed to fight against ‘leeching’, the process of the metals entering into the water. Over time, anything coming into contact with the water will be destroyed.
The same goes for equipment coming into contact with the air. Fan blades and blowers can be slowly eaten up over time. In some cases, this can be even more destructive than wear on pumps and valves. Particles in the air can cause further friction and erosion. Consider for example, equipment in desert locations, where sand is going to get sucked inside at some point. The sand rams into the metal and takes away a tiny bit of material with every impact. In a sense, this is how a sand blaster works. If you were to sand blast a fan continuously, it would basically dissolve into nothing.
The contents of the air are most influential in wearing through fans, blowers, and other similar mechanical equipment. Dirtier air will have higher rates of wear and tear. To some extent, this can even be seen comparing smog heavy locations against regions with cleaner air. The metal particulates in the smog cause wear like sand would. In locations like these, it’s not only necessary, but essential to filter the air input to your HVAC equipment.
The damage we’re watching out for isn’t on a big scale, it’s on a microscopic one, where failure occurs over years of exposure.
One the microscopic level, we also need to consider the actual atoms and molecules themselves. There’s a few dangers we have to look out for here. On the one hand, we need to worry about chemical changes like rust and corrosion. On the other, we need to worry about weakening through fatigue. These are both slow, destructive processes.
From a chemical perspective, rust will cause metal components to weaken and fuse together. This generally happens from oxygen bonding to the metal in question. There’s also the risk of corrosion. When certain metals come into contact, they will exchange electrical charges and begin to corrode.
This has two practical impacts: equipment can seize to itself or it can just fall apart wherever it’s sitting. In both cases, it’s going to be expensive. You perhaps want to hope for a blower to just fall apart more than you want something to rust until it’s seized. It’s important to keep an eye on these mechanical parts over time. As rust or corrosion appears, they need to be removed and replaced.
Fatigue is another issue. This is moreso a problem around the burner and combustion chamber. As the metal heats and cools, the chemical structure can be weakened. Think of it like sticking molten glass into a vat of liquid nitrogen. The glass would shatter as some molecules continue to move with high energy and others become frozen, rigid. The stress of molecules changing states would just shatter the glass.
This can happen to metals over time, slowly. The metal can weaken, sometimes bits of the metal are worn down and leeched into the air as tiny particulates. Eventually, the component will fail, typically wearing holes in themselves or in some cases potentially just becoming blocked off with collapsed bits of metal.
Keep An Eye Out
Mechanical parts last seemingly forever, but that doesn’t mean they’ll never break down. Keep an eye on your blowers, motors, pumps, and bearings. Overtime, these will give out. It’s best to catch the failures sooner than later and be ahead of the game.