For Plating – Cleaner – E-Coat Systems

Eductors use a venturi design, which enables small pumps to circulate large volumes of tank solution. When pumping is used for solution agitation, the use of an eductor will circulate four to five gallons of solution in the tank for every one-gallon you pump. If tanks are heated or require fume exhaust, a major cost saving is realized using solution agitation as opposed to air agitation -- air makeup and heat lost is reduced. In addition, the solution is not subject to the introduction of addition oil or dirt as a result of the air supply.

Tanks have used pumps without eductors for solution agitation for years. Now with the use of eductors, the efficiency of this process is increased. Eductors will reduce the energy consumption of the pump's motor and will probably allow a smaller and less expensive pump to be used to perform the same job.

If you are using  eductors on a fresh or salt water aquarium - Click Here

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Whatever your chemical solution may be, a tank mixing eductor that will greatly enhance the ability of your pumping system to properly circulate that solution. Eductors are constructed of polypropylene, PVDF, cast iron, alloy 20 and 316SS.

Most of the applications that we have experienced in the past will see the following results with just the addition of eductors:

  • 2 to 3 times the circulation rate vs. open end outlets.
  • Reduced amp draw for the circulation pump - Eductors have a payback by reducing your electrical costs.
As the solution is pumped through an eductor's orifice, a low pressure area is created that acts to pull solution from behind the bell shape of the eductor and direct the solution out of the bell end. 
Copy of Bex-3.jpg (12442 bytes)For each gallon of solution that is pumped through the eductor, three or four gallons of additional solution is circulated within the tank.   As one of the most cost-efficient and effective ways for manufacturers to get the best performance from their re-circulating process tanks, it is easy to see why tank mixing eductors are the design of choice for all major manufacturers.


Eductors are currently installed in the following types of re-circulating process tanks:
  • Plating tanks
  • Cleaning tanks
  • Phosphating tanks
  • E-coat paint tanks
  • Sludge tanks
  • Paint booths
  • Anodizing tanks
  • Cooling towers
  • Fertilizer tanks
  • Pulp tanks
  • Decorative fountains
  • Salt water aquariums - Reef tanks

Performance – The flow rate through the eductor is dependent upon the pressure available from the circulation pump. Most systems are the most energy efficient in the 10 to 15 PSI areas. (23 to 35 feet of pressures).  The ratio of pumped vs. circulated will remain the same independent upon the amount of solution being   pumped through the nozzle (orifice).

The below chart is for polypropylene or PVDF eductors only.  Similar results will be obtained with the metal material eductors.  For lower pressures performance

Size - orifice and NPT connection Pressure (PSI) - To convert to TDH multiply by 2.31
8 10 15 20 25 30 35 40
Nozzle Flow (USGPM)
1/4 NPT
3.2 3.5 4.3 5.0 5.5 6.1 6.6 7.0
3/8" **
6.2 7.5 9.2 10.7 11.9 13.1 14.1 15
11.8 13.5 17 19 21 23 25 27
18.7 21 25 29 33 36 39 42
1 1/2"
- 33 41 47 53 58 63 67

Example for above chart:  Using the .48" eductor, with 15 PSI pressure available, the flow rated through the nozzle will be 25 GPM - The total amount circulated will be 125 GPM

smallnew.gif (926 bytes) Penductors** The above .30" orifice eductor is NOW available in a shorter profile with 3/4"MNPT or 1" NPT connections -- save installation time and tank space.  This product is not available from BEX, Serfilco or Spraying Systems !!  
Download bulletin for this new eductor - bulletin 704 - 143KB PDF format

Molded Thermoplastic Eductors - polypropylene and PVDF (Kynar)

To determine circulation, multiply the nozzle flow by five (5).
(1 gallon pumped = 5 gallons circulated)

  • Smaller pumps require less capital $
  • Less electricity required to run pumps $
  • Less friction (heat) created in the pumping system
  • More circulation means less "settling" of solids:
  • Improved performance from filtration systems - use on discharge of filter system
  • Better control of solution uniformity (composition)
  • Less or no air reduced heat loss of tank

    Eductors molded in polypropylene:

    • Good in many applications up to 175 F
    • For alkaline cleaner tanks
    • Will not corrode in most acid solutions
    • Adds no metal/contaminates to solution chemistry
    • Fiberglass reinforced for good mechanical strength
    • Smooth plastic resists build-up of scale and plugging

    Eductors also available in PVDF:

    • Premium quality, chemical-resistant plastic
    • Use for electroless nickel tanks
    • Good in many applications up to 300 F
Metallic Eductors

Investment cast 316 SS – 3/8" – 1 " – provide 5 gallons of solution movement for each gallon pumped through the eductor.

Sand Cast Metals – Cast Iron – Alloy 20 – 316SS (2" and 3" only) – provides 4 gallon of solution movement for each gallon pumped through the eductor.

This diagram shows how eductors are used to promote circulation across a rectangular tank bottom and direct this flow toward the pump intake. Of course, there are numerous possibilities to achieve quite dramatic results when eductors are used in combination with adjustable joints which allow for ultimate "fine tuning" of your system’s flow. In any case, contact KTH Sales to determine the configuration which best suits your specific needs. Pumps and inline filtration systems can be supplied for most applications. Bex.jpg (7324 bytes)

Note:  Most plating solution agitation applications will use 3/8" orifice eductors - solution MIXING applications is dependent upon the size of the tank and the performance of the pump.


Pipe Size Length Largest OD
1/4" NPTMale 3" 1-1/4"
3/8" NPT Male 4 1/2" 2-1/8"
Above performance in short profile - with 3/4" or 1" MNPT 3 7/8" 2-1/8"
" NPT Male 6 3/8" 3"
1" NPT Male 8 1/2 3"
1-1/2" NPT Male 9 7/8" 4-5/8"

Note: Cast metal eductors are available in the above sizes and in 2" and 3" NPT.

Pre Engineered Systems
Penguin Pumps supplies pre engineered systems using P-Series pumps and Penductors  - details

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