Flushing and filtering the lube oil system of your turbine/generator units before initial start-up or after rebuilding can be a time-consuming, costly job.  By working with Semler Industries, Commonwealth Edison Co. and Florida Power & Light Company found a full-flow system that flushes the oil faster than conventional systems and paid for itself after the first use.

Both flushing systems were custom designed and built by Semler Industries, Franklin Park, IL.  According to Loren Semler, president, the cost ranges from $60,000 to $150,000 depending on the specific equipment design and layouts.

The system consists of the following skid-mounted components:

  • 5000 GPM motor-driven centrifugal pump
  • Four full-flow filters with disposable, five-micron filter elements
  • High volume suction strainer
  • Check-valve
  • Flow control valve cluster and system relief valve
  • 600-6000 GPM direct-read flow meters

The equipment is assembled on several skids to facilitate on-site handling and placement.  Semler also offers a skid mounted heat exchanger and flexible 12 in. hose in 8 ft. lengths as options.

Removing particles of debris and rust from a turbine/generator lube oil system has been accomplished by permanent pumps supplied with the oil system, plus partial flow filters.  “Florida Power & Light estimates a minimum duration of oil flushing at seven weeks using this procedure,” said Tom Norwich of FP & L.  “This duration would result in an estimated cost of $165,410.”  This figure, including equipment, fuel and labor, and the time estimate, is due to the small flow rate of oil common to this equipment.

Another alternative is to rent flushing equipment with full-flow filtering.  At Commonwealth Edison’s Powerton Unit #5, a rental unit was used.  “The flushing and filtering process took nearly seven weeks at a cost of #$88,000,” and CECO’s Les Byrd.  “Adding the operator’s wages and the price of additional filters, the total cost was nearly $100,000.”  The cost runs high because rental charges are based on job-site hours, not flushing-operating hours.  In addition to the high cost, the rental equipment was not always available when needed most.

Both utilities were approached by Semler with a third alternative.  They were told that savings were available by purchasing the equipment necessary for oil flushing.

Case Evaluation – FP & L Finds Buying is Cheaper

The Florida Power & Light Co. construction department (at their Manatee plant site) wrote a specification for a portable flushing unit.  Several bids obtained indicated the unit could be manufactured for about $58,000.  Since this figure indicated a potential savings, FP & L’s financial department was contacted to perform a study regarding rental costs versus purchase of the equipment.  “The finance department projected a savings of $136,000 upon completion of flushing four 775-MW fossil units and one 802-MW nuclear unit (all to be placed in service between 1976 and 1981),” said Norwich.  “Based on these conditions, we decided to purchase the flushing unit.”

After having flushed  two turbine/generator oil systems, FP&L reported that the first unit flush required 21 days and the second 27 days.  The actual days between start and finish of the oil flushes were 35 and 41 days respectively.  Based on the rental charges quoted, the cost of these flushes would be approximately $52,000 and $74,520, plus stand-by time.  “The flushing unit has been paid for during the first oil flush, “ notes Norwich.

Since acquiring the oil flushing system, Florida Power & Light has leased the equipment to Westinghouse for use at another location.  “Whenever the equipment is not in use by FP & L,” Norwich points out, “ it will be available for lease to other companies.”

Case Evaluation – CECO Cuts Flush Time By 85%

Commonwealth Edison also purchased the full-flow flushing system from Semler Industries after their experiences at Powerton Unit #5.  “Using the full-flow system at Powerton Unit #6 took nearly seven weeks,” comments Bird, “mostly due to labor problems and inexperience of setting-up and handling the equipment.  We use the system next at Collins Unit #3.  With a little advance planning and on-site technical support from Semler, the time was cut to seven days.”  Similar to FP & L, CECO feels the equipment paid for itself shortly after the first setup.

Within one year predicted Byrd, “we will have used the flushing equipment twenty times.”   While most facilities will flush only twice per year during planned down time, the system can be moved to multiple turbine oil locations and used frequently.

Commonwealth Edison adapted the flexible 12-in. diameter hose to their system.  This allows them to hook-up in straight-line, angle and side-by-side arrangements.  “This gives us the flexibility to use the equipment on nearly every large unit in our system,” added Byrd.

Byrd says said Commonwealth Edison’s turbine oil flushing unit will be made available to all its tie-line utilities as part of an ongoing equipment interchange program.


Considering that Semler Industries is still working on Turbine Oil Flushing Systems yet today, after three decades experience, we would gladly look at your application and size the components necessary for your plant.  Experience, results and repeat installations after 25 years speaks volumes of the satisfaction customers find in Semler Industries.


  1. Electric Light and Power Magazine, n.d. (prior to 1985)

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