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Rotation and Discharge Code Builder

Run the Rotation and Discharge Code Builder MicroSim Fullscreen

This p5.js sketch is built on the shared FanPedia MicroSim kit. To run it in the p5.js editor, add the kit files (fanpedia-sim.css, fanpedia-core.js, fanpedia-p5.js, fan-codes.js and fan-drawings.js from ../shared-libs/, or their published URLs) to the editor's index.html before pasting the sketch.

About This MicroSim

A centrifugal fan's rotation and discharge code tells the factory which way the wheel turns and where the outlet points, both as seen by an observer on the drive side. The code can be written in letter form (CW THD) or angle form (CW 90). This MicroSim gives you eight job cards, in a fixed order, each describing a fan and its outlet in words. For each card you choose a rotation and one of the eight discharge letter codes, or "Not offered", and submit.

After every submission the sim draws the drive-side outline of the housing with the outlet in the answer's direction, a rotation arrow, a small dial showing the angle measured from straight up in the direction of rotation, and both code forms. The first submission on each card is scored; one unscored retry follows. A correct submission reads "✓ Correct: ."; an incorrect one shows the card's reason followed by the correct answer. The running score reads "Codes correct: n of 8", and mastery is 7 of 8 on the first attempt.

After card 8, free practice (the sim's Explore mode, never scored) unlocks and the summary shows your first-attempt score, the mastery line and any missed cards. Choose SWSI or DWDI, a rotation, and a discharge angle from 45° to 360° in 45° steps, and the outline and code update at once. On a DWDI fan, 225° (Bottom Angular Down) shows "Not offered on DWDI".

The job cards are illustrative scenarios. Discharge names, letter codes, angle forms and the DWDI discharge list come from FanPedia (PDF pp. 46–49) and Chapter 13.

The rule the sim uses

Start with the outlet pointing straight up (360°) and turn it through the discharge angle in the direction of rotation: clockwise for CW, counterclockwise for CCW.

Code Angle CW outlet points CCW outlet points
UBD Upblast 360 up up
TAU Top Angular Up 45 up and right up and left
THD Top Horizontal 90 right left
TAD Top Angular Down 135 down and right down and left
DBD Downblast 180 down down
BAD Bottom Angular Down 225 down and left (SWSI only) down and right (SWSI only)
BHD Bottom Horizontal 270 left right
BAU Bottom Angular Up 315 up and left up and right

How to Use

  1. Read the job card: fan type, rotation and outlet direction, all from the drive side.
  2. Choose a rotation and a discharge (or "Not offered") under Your code, then press Submit code.
  3. Read the feedback and study the drawn housing. Use Retry (unscored) if you want another try; it never changes the score.
  4. Press Next card. After card 8, press Start free practice (or change any Free practice control), read the summary, and explore fan type, rotation and angle.
  5. Press Start over at any time to clear the score and return to card 1.

Keyboard: Tab moves between the controls and the arrow keys change a selection. Enter submits your code, or goes to the next card once the feedback is shown. Enter or Space also presses a focused button.

Data label: "Job cards are illustrative · Source: FanPedia PDF pp. 46–49", shown at the bottom left of the drawing.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

<iframe src="https://moroshek.github.io/FanTASTIC-textbook/sims/ch13-rotation-discharge-code-builder/main.html"
        height="632px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Learning Objective

The learner will apply the drive-side rotation and discharge-angle conventions to write the correct rotation and discharge code, in letter form and angle form, for a described centrifugal fan (Bloom: Apply, verb: apply).

Audience

Fan sales, application and order-entry staff, and engineering students who specify or order centrifugal fans.

Duration

10–15 minutes

Prerequisites

Drive side, clockwise (CW) and counterclockwise (CCW) rotation, discharge position, discharge angle, SWSI and DWDI fans, Bottom Angular Down discharge, and DWDI discharge limits, all covered in Chapter 13.

Activities

  1. Predict (8 min): Work through the eight job cards. Before each submission, say the outlet direction aloud and count quarter turns from straight up in the direction of rotation.
  2. Check (2 min): After each card, compare the drawn outlet and the angle dial with your prediction; use the unscored retry on any card you missed.
  3. Explore (5 min): In free practice, fix the angle at 90° and switch between CW and CCW. Note that the outlet mirrors left to right. Repeat at 45° and 315°, then try 225° on a DWDI fan.

Discussion Questions

  1. Why does CW 90 blow right but CCW 90 blow left, while 360 and 180 are the same for both rotations?
  2. Why must rotation be judged from the drive side and not the inlet side?
  3. A layout calls for a DWDI fan blowing bottom angular down. What could you offer instead?

Common Misconceptions Addressed

  • The same angle number points the same way for CW and CCW fans.
  • Rotation can be judged from the inlet side.
  • Every discharge is available on every centrifugal fan, including DWDI.

Assessment

  • First-attempt score shown as "Codes correct: n of 8"; mastery is 7 of 8 on the first attempt.
  • Free practice is exploration and is not scored.
  • Ask learners to explain card 6: why is "Not offered" the right code?

References

  1. Twin City Fan & Blower. FanPedia: The Fan & Blower Encyclopedia, pp. 46–49 (discharge positions, rotation and DWDI discharges). PDF
  2. Twin City Fan & Blower. FanPedia online.
  3. AMCA International. ANSI/AMCA Standard 99, Standards Handbook (designation for rotation and discharge of centrifugal fans). AMCA