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Wet Stacking: The Effects & Prevention

Wet Stacking: The Effects & Prevention

The effects of wet stacking are difficult to overcome for diesel engines and generators when these units operate under a 30% performance threshold. Without reaching correct temperatures, fuel that is unburned can wreak havoc on your engine.

LionHeart Critical Power Specialists will help you avoid wet stacking and its subsequent impact on unit life and efficiency. Our EGSA Field Service Engineers will repair damaged units and we will provide you with a plan to avoid wet stacking in the future.

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Defining Wet Stacking and Why it Should be Avoided

“Wet stacking” is a condition that affects diesel engines and is caused by unburned fuel entering into the exhaust system.
When diesel engines or generators are run under lightly loaded conditions, these units can have low combustion temperatures, which leads to inefficient combustion and an incomplete burn of the available fuel. The remaining fuel leaves carbon deposits that collect in a wide variety of areas, from the combustion chamber to the exhaust system. This unburned fuel can be identified by the presence of a black, oily substance, which comes from the exhaust manifold(s), exhaust piping, and turbo charger(s). Collections in these areas can hurt your unit immensely.

The Negative Effects of Wet Stacking

There are a wide variety of problems that can occur if your diesel engines or generators experience wet stacking, including:

  • Loss of engine performance – Wet stacking can hurt your emissions and efficiency, hurting the environment and your bottom line.
  • Fouled injectors – Faulty components like damaged injectors need to be replaced and can stop your unit in its tracks until repairs have been made.
  • Carbon buildup – With wet stacking, carbon droplets are not only harmful to your unit, but they can be dangerous if not burned correctly.
  • Premature engine/generator wear or failure – A reduction of life means a costly replacement but could also contribute to low power and higher maintenance costs until you make the change.
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Load Bank Testing and Installation

Load bank testing your generator not only verifies system capability and performance, but it also removes the excess, unburned fuel created by wet stacking.
Additionally, completing testing is often required by code or law to remain in compliance. It provides a comprehensive review of your system to avoid costly complications from wet stacking.
Talk with LionHeart about load bank testing for your engine or generator. We can also work with you to complete permanent load bank installation, if necessary.

How to Prevent Wet Stacking

The effects of wet stacking can be rectified by running the generator set at or above 75% of the generator’s nameplate rating. This allows for increased exhaust temperatures, which vaporize the unburned fuel in the exhaust system.

Select load bank testing services from LionHeart on an annual basis. This can alleviate heavy carbon buildup that occurs if wet stacking goes unaddressed. Wet stacking that is not properly handled will almost always result in component damage that can ultimately lead to component repairs, replacements, or in severe cases, a major engine overhaul.

NFPA Guidelines & JCHAO Requirements

The National Fire Protection Association (NFP) has guidelines to reduce the effects of wet stacking on critical power systems. All of the load bank testing services supplied by LionHeart are created in compliance with these guidelines.
In Level 1 and 2 applications, it is required to exercise the unit, at minimum, every month for 30 minutes. Depending on the application, this should be completed using one of the two methods:

  • Loading that maintains the minimum exhaust gas temperatures, as recommended by the original equipment manufacturer (OEM).
  • Under operating temperature conditions, and at no less than 30% of the emergency power supply (EPS) standby nameplate kW rating.

Learn more about guidelines set forth by the NFPA to promote healthy operation that removes the risk of wet stacking in your systems.
Additionally, the Joint Commission on Accreditation of Health Care Organizations (JCAHO) accredits health care institutions and provides feedback on their requirements for testing generators. Discover JCAHO specifications.

Avoid Wet Stacking with Lionheart Critical Power Specialists

The expert team at LionHeart has the skillset and resources to help you avoid wet stacking. Save time and money, and prolong the life of your diesel engines and generators with our assistance. Our engineers have years of experience with these systems and know how to set your operation up for success.
In addition to load bank testing and installation, we provide a wide variety of additional services and have certified preventative maintenance programs that fit your unique requirements.

For more information or to get started, contact us online. You can also send us an email at [email protected] or call 844-LHPOWER (844-547-6937).


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