How to Avoid Wet Stacking Industrial Generators

Date Published: May 3, 2019

Avoid wet stacking industrial generators

Diesel engines are commonly used in the industrial equipment industry because of their reliability and power. However, a common issue with diesel-powered industrial generators is a phenomenon called wet stacking.

Wet stacking occurs when unburned fuel builds-up in an industrial equipment engine’s exhaust system.

This buildup results in decreased engine performance and reduced maximum power, pollution, premature engine wear and even long-term damage if the industrial generator is being wet stacked for long periods of time.

Learn more about wet stacking, including tell-tale signs your generator is wetstacking and how you can prevent it from occurring and slowing down your industrial jobsite productivity:

What is wet stacking?

Like all internal combustion engines, to operate at maximum efficiency, a diesel engine has to have exactly the right air-to-fuel ratio and be able to sustain its designed operational temperature for the complete burn of fuel.

Diesel engines rely on the hot compressed air in the cylinder to vaporize and ignite the fuel. When air becomes cooler than the design temperature, conditions for combustion are less than ideal.

This causes the fuel to ignite and burn, but it doesn’t burn completely. The unburned fuel is then exhausted and noticed as wetness in the exhaust system, hence the term “wet stacking.”

Typical wet stacking scenarios in industrial applications

Wet stacking can occur in industrial generators due to a number of reasons, including:

  • Operating the generator at a light load (less than 60% of its rated power load) for an extended amount of time
  • Excessive engine idling
  • Running the industrial generator with too much or too low fuel
  • Not using the generator for a long period of time
  • Operating the generator with the incorrect air-to-fuel ratio

Although not ideal, these situations are increasingly common on industrial jobsites, especially in remote locations where power is not readily available and low amounts of power are required to power things like site shack lights, creating a wet stacking scenario.

How can I tell if my industrial generator is wet stacking?

There are many tell-tale signs that a generator is wet stacking. Some of these signs can include:

  • A continuous black exhaust smoke coming from the generator’s exhaust pipe
  • A dark substance dripping from the engine’s exhaust pipes
  • The formation of soot or hard carbon deposits
  • Moisture gathers in the generator’s internal components
  • Hissing noises are emitted during operation

How can I prevent wet stacking?

Prolonged operation at low loads can lead to permanent engine damage, requiring a major engine overhaul. Costs of an overhaul can run so high that replacing the industrial genrator is the most cost-friendly option.

The general solution for wet stacking is a few hours of operation at a load of about 75% of the generator’s nameplate rating or more, raising the exhaust temperature high enough to vaporize the unburned fuel in the exhaust system and blow out the soot and carbon deposits.

If a unit has a history of extended operation at low load, or if there’s no documentation that it’s been exercised recently at adequate load, it’s important to have a professional generator maintenance expert manage the load testing procedure.

A generator maintenance expert can perform load testing procedures to determine if the engine can remain operational or if it needs an overhaul. If wet stacking is caught early enough, the professional can do a load test using the building’s load or using an external portable load bank. This burns off the unburned fuel and corrects the problem.

Running your industrial generator for a few minutes a week at a load that meets the operational temperature is a great preventative measure to prevent wet stacking, along with having your generator regularly serviced by an experienced technician.

In addition, using the right generator size for your job site is crucial. Nearly all industrial equipment rental companies supply various sizes of generators. If you are unsure about your load requirements, renting is likely the best path to choose as you determine the right generator for your needs.

Most experienced industrial equipment companies will allow you to swap, trade and return your equipment as you need and can offer different combinations of power to fit specific requirements.

If a unit has a history of extended operation at low load, or if there’s no documentation that it’s been exercised recently at adequate load, it’s important to have a professional generator maintenance expert manage the load testing procedure if you plan on purchasing the equipment.

At Axiom Equipment Group, we offer customers the option to trade and/or return your equipment as you need and can offer different combinations of power to fit specific requirements.

Our experienced team has decades of combined experience in equipment rental, sales and service.

At Axiom Equipment Group, we believe in ZERO DOWNTIME so much that we stand behind it with a unique iron clad promise that combines the industry’s most reliable equipment fleet with a rapid response program, around-the-clock availability, expert service and a financing option to fit every budget.

Contact us today for your industrial equipment and servicing needs.