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Vertical Turbine Cooling Tower Pump Repair

A Vertical Turbine Pump is a specific design of pumping equipment used in applications where a fluid is in a sump, such as a below ground tank, a reservoir, a pond, a well or a cooling tower sump.  Vertical turbines are selected as the right piece of equipment when the fluid is relatively clean, the flow need is constant and the installation is such that a flooded suction to a standard centrifugal pump is not possible. Vertical turbine pumps are a good choice because they are relatively high in hydraulic efficiency, an energy saver, and eliminate the need for priming.

The major components of a vertical turbine are the suction bell, the bowl assembly, the discharge case, the column pipe assembly, discharge head, stuffing box assembly, and motor with motor shaft. All of these components work together to do the work of moving a fluid.

The unique aspect of a vertical turbine is that they are not a “pump in a box”. Each turbine pump is considered a “custom” pump – that is that each pump is designed and built for a specific application and must be defined when purchasing. It is the classic engineered product, and requires a thorough knowledge from a pump professional in order to process.


Duplex Cooling Tower Pumps

The defining characteristics of a vertical turbine are:

–         overall length of the pump, from the ground level to the end of the suction bell. (based on the sump depth, distance to the fluid)

-         the flow rate and output pressure (based on the system requirements)

-         construction of each piece (metallurgy required for the application)

-         type of column assembly (open line shaft, enclosed line shaft, etc.)

-         type of discharge head (above ground, below ground, etc.)

-         Driver type (electric motor, diesel engine, right angle gear, etc.)

-         Stuffing box (packing, mechanical seal, type, etc.)

Stuffing Box with Mechanical Seal

The average vertical turbine pump is relatively heavy (700 lbs or more) and long (8 ft or more), which requires the use of rigging equipment, experienced professional technicians and crane equipment to handle for repair.  Repairs are not typically done in the field, as many types of shop repair equipment are needed to perform all tasks of a repair job.

Repairs on a vertical turbine are a major undertaking, because of the size and weight, and because of the expertise required to disassemble, inspect and replace/repair worn elements of the unit and reassemble and test. This is not a job for even the most experienced of facilities maintenance technicians. 

             Removal Process

During disassembly the shafts are inspected for wear near the shaft bearing, bushings and stuffing box area.  The bowl assembly and the bottom bushings are measured with a micrometer for wear.  Each impeller is inspected for damage, wear and corrosion damage, and noted for suitability to be reused in the unit.

Typically, the column assembly is sanded and ground to bare metal. Any rust is removed and new bearings are installed. Severely damaged, worn or corroded parts are replaced.

Finally a new stuffing box will be installed and any wearing parts are inspected and replaced.

The motor should be completely check out and tested, and any repairs should be done while the unit is in the shop.

After the replacement and refurbishing process, the shafts are checked for straightness then the entire unit is reassembled.

The entire pump is primed and repainted with industrial grade machinery enamel. Other choices for industrial coatings can be selected at the direction of the customer.

 At this point the pump and motor are reinstalled and the motor shaft is installed. Impellers clearances are adjusted in the field during start up and testing. Rotation is checked and leak, vibration and flow tests are performed.

Vertical Turbine Pumps can run continuously for many years with a high efficiency and dependability.  However, to continue to achieve these efficiency levels maintenance is required.

Typical maintenance checks include:

  • Check oil level in motors
  • Vibration checks on the pump
  • Pressure gauges for output pressure
  • Check for noise in the equipment
  • Check amp draw in the motor

  Bowl Assembly with Suction Bell

 

Suction Case Corrosion

 

      Discharge Head  

   Pump Disassembled   

Robert Brown Associates offers a complete maintenance agreement for inspecting pumps, rotation, leakage, and more. This is a key aspect to keeping the vertical turbine pumps efficient and running smoothly, especially if there are no mechanics on-site to do the required checks.

Tom Halley
President
Robert Brown Associates

 
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