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Parts of a Centrifugal Scroll Housing

Run the Parts of a Centrifugal Scroll Housing MicroSim Fullscreen

About This MicroSim

This MicroSim is a drawing of a single width, single inlet (SWSI) housed centrifugal fan seen from the inlet side. Part of the inlet-side sheet is cut away so you can see the impeller inside the scroll, and an inset shows a section through the inlet, where the inlet flange, inlet collar and inlet funnel sit one behind the other. Ten parts are outlined with dashed lines: the housing scroll, housing side, cutoff, wiper bar, inlet funnel, inlet collar, inlet flange, outlet (discharge) flange, framing and pedestal.

The drawing is a simplified illustration based on FanPedia p. 60 (the SWSI housing construction drawing) and p. 59 (housing features). It is not to scale and is not a specific Twin City Fan model.

The quiz names each of the 10 parts once, in a shuffled order, and you click where that part is. You get two attempts per part. Only first-attempt answers count toward the score, and mastery is 9 of 10 correct on the first attempt. Explore mode is never scored.

How to Use

  1. Explore mode (the starting mode). Hover over an outlined part to see its name; click it to open its infobox. Parts you have opened get a ✓ mark and keep their label, and the counter shows how many of the 10 you have visited.
  2. Quiz mode. Press Quiz. The labels disappear and a prompt such as "Click the cutoff." appears above the drawing. Click that part:
    • Correct: "✓ Correct:" and the part name. The part keeps a solid outline and its label for the rest of the quiz.
    • Wrong on the first attempt: "✗ That is the" part you clicked, then "Try again."
    • Wrong on the second attempt: the correct part is highlighted and marked "Answer", its infobox text is shown, and the item counts as missed.
    • Clicking an empty area of the drawing does nothing and uses no attempt.
  3. Press Next part after each answer. The toolbar shows "First-attempt correct: n of 10".
  4. After the tenth part, the summary shows your first-attempt score, whether you reached mastery (9 of 10), and every missed part with its infobox text. Press Retake quiz to reshuffle and start again with the score reset, or Back to explore to review.

Keyboard: Tab moves between the parts (outlet flange, cutoff, scroll, side, wiper bar, framing, pedestal, then the inset parts) and the buttons; Enter or Space selects a part. After an answer, focus moves to Next part, so Enter goes on.

Narrow screens: when the drawing is narrower than about 640 px, the callouts become numbers, and the names of the parts you have opened appear in a key list below the drawing.

Data label: "Simplified illustration, not to scale · Based on FanPedia pp. 59–60 (SWSI housing)", shown below 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/ch04-scroll-housing-parts/main.html"
        height="777px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Learning Objective

The learner will identify the ten named parts of a single width, single inlet centrifugal scroll housing on a drawing of the fan (Bloom: Remember, verb: identify).

Audience

Adult professional development: new application engineers, sales staff, representatives and facilities staff.

Duration

10-15 minutes

Prerequisites

  • Chapter 4, section "Scroll Housings": scroll housing, housing scroll, housing side, cutoff, wiper bar, inlet funnel, inlet collar, inlet flange, outlet (discharge) flange, framing and pedestal.
  • Chapter 2: velocity pressure and static pressure, for the idea that the growing scroll slows the air and recovers static pressure.

Activities

  1. Explore (4 min): Hover over and open all ten parts. For each one, say whether it shapes the airflow (scroll, cutoff, wiper bar, inlet funnel), connects to ductwork (inlet collar, inlet flange, outlet flange) or holds the fan up (housing side, framing, pedestal).
  2. Trace (2 min): Put a finger on the cutoff and follow the scroll the way the gap grows. Which way does the impeller turn, seen from this side?
  3. Quiz (5 min): Switch to quiz mode and locate all ten parts without going back to explore mode.
  4. Review (3 min): Read the missed list, open those parts in explore mode, then press Retake quiz for a new order.

Common Misconceptions Addressed

  • The scroll housing is only a protective cover: the scroll's infobox explains that its growing passage slows the air and recovers static pressure.
  • The cutoff and the outlet flange are the same thing: they are separate parts at opposite ends of the outlet, the cutoff inside the housing next to the impeller tips and the flange on the outside rim where the duct bolts on.
  • The inlet collar and the inlet funnel are the same part: the inset shows the collar as the outside duct connection and the funnel as the curved piece that guides air into the impeller eye.

Assessment

  • First-attempt score shown as "First-attempt correct: n of 10"; mastery is 9 of 10 on the first attempt.
  • Hovering and opening infoboxes in explore mode is exploration, not evidence.
  • Follow-up question: a technician reports a "dented bolting rim where the duct leaves the fan." Which part is it, and why is it not the cutoff?

References

  1. FanPedia: The Fan & Blower Encyclopedia (PDF) - Twin City Fan & Blower; p. 59 lists the housing features and the wiper bar's job, and p. 60 is the SWSI housing construction drawing this illustration is based on.
  2. FanPedia online - Twin City Fan & Blower's online version of the encyclopedia.
  3. Chapter 4: Centrifugal, Axial and Mixed Flow Fans - the section "Scroll Housings", which defines every part in this drawing.
  4. Chapter 7: Housing Construction and Exploded Views - the same housing shown as an exploded view.