Case Study: High-efficiency, low-noise impellers for car wash systems


Global leader in car wash systems and equipment


  • Retrofitting car wash dryers
  • Existing plastic housing shall remain unchanged
  • Outlet air velocity shall be similar to the actual velocity (~140 mph)
  • System shall be 5 dB(A) quieter


  • Highly efficient diffuser impeller
  • Corrosion-resistent aluminum design
  • Airfoil blade geometry for optimized sound
  • Specially adapted inlet cone to fit existing housing


  • ~ 10% less electrical power in operating mode at same air velocity
  • Easier installation and maintenance due to smaller and lighter impeller
  • ~ 5 dB(A) quieter operation

Project Overview

The client approached punker with the request for an alternative impeller, which fits their existing housing and performs equally or better than the existing impeller. punker designed a solution based on an efficient and quiet impeller with aluminum airfoil blades and a corresponding inlet cone. Practical field tests in the car wash systems showed that this combination delivers similar air speed with less power consumption and less noise.

Our Customer

Our client produces, markets and services a complete range of car wash systems with conventional brushes, cloth washers and high-pressure water jets for cars and commercial vehicles. They sell complete car wash systems (Rollover systems, tunnel systems and self-serve car wash systems) – but also service, chemicals, ancillary products. Their customers include gas stations/convenience stores, retail car wash operators, auto dealers and fleet operators. Each day, equipment manufactured by this group of companies washes over two million vehicles around the world.


Our client’s attention was drawn to punker through its German parent company, which looks back on many years of cooperation with punker. The global leader of car wash systems’ subsidiary in the USA was looking for an alternative impeller for their car-wash-blower, which fits their approved spiral housing installed in many car-wash systems. The housing width was extremely wide, compared to  punker’s optimal design requirements for installation width (including impeller and inlet cone). Finding a satisfying solution without any losses in air, acoustic and electrical performance was the main challenge.


punker tested the overall performance of the customer’s existing blower system at their own test facilities by measuring air performance (static pressure vs. air-flow), noise and electrical power. punker elaborated different design options based on their aluminum airfoil impeller. The solutions where discussed with the client’s engineers and were validated at the client’s test facility regarding installation applicability for new and existing dryer systems.

Advantages and disadvantages were discussed with the customer and the best identified design received a final improvement by the engineer’s collaboration between the client and punker to reach the performance optimum. The benefits for the customer are ~10% less electrical power in operation mode, approx.  5 dB reduced noise, and a smaller and lighter impeller which reduces the loads on the motor bearings.

Your project with punker

Are you also planning an innovative product that will revolutionize the market? Rely on the support of the punker R&D team. Our design engineers will work with you to find the perfect air movement solution for your project.

Do you already have a detailed view of your new product and can provide information on air performance, drive and design specifications? Then simply send us these details using the technical questionnaire below and our team will immediately define suitable solutions for you from the broad punker portfolio.

Or are you looking for a sparring partner who will work with you to develop ideas for a new or optimized series generation and accompany you all the way to series production? Then simply contact our application engineers by e-mail at

Technical Questionnaire




    Your eMail address*:




    Attention: Frequently all operating details are either not known or only inaccurately known. You must therefore as a manufacturer make sure by suitable tests that the correct fan wheel has been selected. When the following questions are answered as comprehensive as possible, we can submit a proposal as quickly and as defi nite as possible. Please give us further details on a supplementary sheet. This questionnaire on no account replaces a technical specifi cation (TSP).

    1. General Information

    1.1. Fan application (type of unit and appliance, rail application, compressor, etc.)

    1.2. Are there any special requirements on safety conditions? (e.g. explosion protection, danger of accident at wheel failure, etc.)


    Please state special requirements:

    1.3. Medium to be handled and its state (e.g. smoke gas with t max = 300° C, dust laden air or similar)??

    2. Air Duty

    2.1. Volume flow
    V' = m³/hcfm

    2.2. Static pressure increase
    Δpfa = PainWG

    2.3. single flow/double flow?

    2.4. Density of the medium
    rho = kg/m³lb/ft³

    2.5. Max. media temperature
    t = °C°F

    2.6. Max. A-rated sound power level
    Lw = dB(A)

    2.7. Other technical details (e.g. max. flow speed, special curve steepness, etc.)?

    3. Drive

    3.1 Is the speed variable?


    minimum ; maximum rpm
    fixed speed rpm

    3.2. Direct motor drive

    n = rpm

    3.3. Is a maximum motor power specified?


    maximum motor power Pw = kWhp

    3.4 Operating mode?

    S1 - IEC 60034-1other operating mode

    other operating mode =

    4. Dimensions and Constructional Execution of the Fan Wheel

    4.1. Can a standard fan housing be used?


    max. dimensions of spiral housing:

    4.2. Are certain main wheel dimensions defined?

    main wheel dimensions:

    4.3. Hub bore
    Ø d = mm, fit
    with/without keyway?


    4.4. Hub model and arrangement (e.g. inside the wheel, outside, etc.)

    4.5. Material of wheel body


    other material:

    4.6. Additional surface protection


    other surface protection:

    4.7. Additional specifications

    5. Demand, Pricing

    5.1 You would like to request an offer for:

    Sample wheels: pcs.

    (later) batch: pcs/year

    Lot size pcs/order

    5.2 planned start of production TT/MM/JJJJ


    With Xcarwash, punker offers a high efficiency, sound optimized air movement solution for car wash dryers that combines a diffuser airfoil impeller with an inlet cone that is optimally adapted to deliver high discharge velocity for mininum drying times.

    Visit the product page for more information