Solberg Manufacturing | Filters, Silencers, Vacuum Filters, Oil Mist Eliminators, Separators

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Peak Load Gen-Sets

Eliminating Crankcase Emissions and Controlling Crankcase Pressure.

The Challenge

A Red Bluff, California power station experienced excessive positive pressure in the crankcases of its Wartsila gen-sets. This led to oil leaks through the seals and valve covers. Additionally, significant visible emissions were exhausted outside of the building and into the atmosphere. Both of these problems were unacceptable from a performance, maintenance and environmental standpoint, and the goal was to correct them as soon as possible.

Plant personnel diagnosed that their current crankcase oil mist eliminators were undersized. For every two gen-sets, there was only one vacuum assisted oil mist eliminator to handle the crankcase blow-by. The units did not have the capacity to capture the blow-by or overcome the differential pressure caused by the internal separator elements. The Operations Manager contacted Solberg to help confirm the diagnosis and offer a solution.

The Equipment

Engine Gen-Set: Wartsila 18V 200SG
Crankcase Blow-By Flow: 50 CFM
Existing Crankcase Pressure: + 3” H20
Required Crankcase Pressure: +1 to +1.5” H20


The Solution

Solberg designed a Vacuum Assisted Oil Mist Eliminator (VAE) to capture the blow-by emissions and regulate crankcase pressure. This was a collaborative process in which Solberg Engineers and Sales personnel consulted directly with the Operations Manager on several occasions over a four month period to ensure the ideal design. Since
Wartsila specified a pressure of +1” to +2” of H20 in the crankcase at all times, the Solberg VAE was built to maintain this level.


After delivering one VAE assembly, installation was handled locally by the Operations Manager and his staff. During the process, Solberg provided instructions and detailed information regarding mounting and start-up.


System Components

Internal Air/Oil Separator Element: 99.97% efficient for .3 micron oil mist. Designed to eliminate visible blow-by emissions

Regenerative Blower: Creates vacuum to overcome differential pressure caused by the separator element and to maintain the optimal pressure level in the crankcase

Re-circulation Pipe: Circulates the discharge flow and pressure from the blower to balance the vacuum produced at the intake. This flow pattern allows the system to maintain the operating pressure of +1”to +2” H2O in the crankcase

Vacuum Relief Valve: Opens to allow air into the blower if it produces vacuum over -40” H20
Oil Return Drain: This drain runs back to the lube oil reservoir. To ensure proper drainage, the line is submerged below the low oil level.

Differential Pressure Gauge: Monitors pressure differential for element maintenance



During a follow-up visit by Solberg Engineers and Sales, the mist eliminators functioned well. With a flow meter, the blow-by was measured at 50 CFM from each engine. This reading confirmed that the plant’s existing mist eliminators were undersized. The blower used on their existing units was only rated for 72 CFM. When tying together two 50 CFM engines, the backpressure and oil mist challenge was excessive.

On the other hand, the Solberg VAE was sized to a capacity of 150 CFM to minimize differential pressure and accommodate future increases in blow-by. A digital differential pressure monitor, displayed 0” H2O pressure/vacuum produced by the VAE. This allowed the engine to maintain its standard operating pressure of +1” H2O in the crankcase. Additionally, the Solberg VAE clearly eliminated the plant’s previous visible emissions.

Since this visit, the Operations Manager ordered seven identical VAE systems for the plant, and is considering eight more for the remaining engines. Solberg staff will stay in contact with him to ensure the VAE’s continue to satisfy his needs.

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