In Short
How long an exhaust silencer lasts depends on the material and finish chosen for the site and on how the set is run. Condensate, short running periods and coastal or industrial air all promote corrosion, so matching the material to the conditions and providing drainage is what gives a long service life.
A silencer is a steel box that sits in the hottest, wettest and dirtiest part of a generator installation. Some last for decades. Others are streaked with rust within a couple of seasons and start to leak. The difference is rarely bad luck. It comes from where the unit stands, how the set is run and what material and finish were chosen for that situation.
Why Exhaust Systems Corrode
Corrosion in an exhaust system attacks from two sides. Inside, the gas carries moisture and acidic residues from the fuel, and these turn aggressive when they cool and settle as condensate. Outside, the shell meets rain, damp air, dust and, near the sea or a road treated for ice, salt. A silencer that is only hot for a short time and then cools down is exposed to both, again and again.
That is why a standby set that runs for a few minutes each week can have a worse-looking silencer than a set that runs all day. Short runs never dry the inside out.
Matching the Material to the Site
There is no single best material. Plain steel with a good paint system is the sensible and economical choice for many inland sites with a dry, mild climate. Where the air is salty, humid or polluted, or where the set runs only in short bursts so condensate stays inside, a more resistant material is worth the extra cost, because replacing a silencer on a roof or inside a container is far more expensive than buying the better unit in the first place.
The finish matters as much as the base material. A heat-resistant coating, a protective paint or an outer cladding each does a different job, and the right one depends on how hot the shell gets and what it is exposed to.
Condensate, Drains and Short Running Hours
Whatever the material, moisture that collects inside a silencer does damage over time. Units are normally fitted with a drain so that condensate and rainwater can be let out, and the drain needs to be at the right point for the way the silencer is mounted. A silencer that stands upright under an open outlet without a cap or a drain will fill with rain in the first wet season.
Sets that mostly stand idle, and sets that run lightly loaded for long periods, are the ones that produce the most condensate. They deserve the most attention when the material and the drain arrangement are chosen.
Coastal, Industrial and Harsh Sites
Coastal plants, chemical works, fertiliser stores, offshore and marine installations and sites with heavy industrial fumes all attack the outside of the shell faster than a normal inland site. The same goes for installations where the silencer sits right next to a wet process or a washdown area. For these sites the material, the coating and the fixing details should be agreed at the enquiry stage, not after the first signs of rust.
Tell AXON where the unit will stand, how often the set runs and what the air around it is like, and the material and finish are proposed to match the job.
What the material choice covers
- The shell and internal parts, matched to the site and the way the set is run
- Outer protection: paint, heat-resistant coating or cladding
- Drain points and outlet protection against rain
- Behaviour of the unit on standby sets with short running times
- Coastal, industrial and chemically exposed locations
- Expected service life and the points to inspect over time
What to send with an enquiry
- Site location and whether it is near the sea, a road treated for ice or an industrial plant
- Indoor or outdoor installation and the mounting position
- Fuel type and how often the set runs, standby or prime duty
- Any wish for a specific material or finish
- Exhaust route and any other items in it
- Expected service life of the installation
Questions we are often asked
Why does my generator silencer rust so quickly?
Usually because moisture and fuel residues collect inside after short runs, while rain, damp air or salt attack the shell from outside. The material and finish were probably not matched to the site.
Is a more resistant material always necessary?
No. For a dry inland site with regular running, a well-protected standard unit is often enough. Coastal, humid or industrial sites and standby sets with short running times are where it pays off.
Does a standby generator corrode faster than one that runs every day?
Often yes. Short runs leave condensate inside the silencer, and the unit never dries out properly between starts.
Does the outer finish matter as much as the material?
Yes. A suitable coating or protective layer slows corrosion on the outside and keeps the unit looking and performing as intended for much longer.
What does AXON need to propose the right material?
The site location and environment, the way the set will run, whether the silencer stands indoors or outdoors, and the wanted service life. AXON then proposes a material and finish to match.