Stuffing Box Seal With Gas Purge¶

Run the Stuffing Box Seal With Gas Purge MicroSim Fullscreen

About This MicroSim¶

This MicroSim puts ten numbered markers on FanPedia's exploded view of a stuffing box type shaft seal with gas purge (page 155). The seal is drawn pulled apart along the shaft, in the order it goes together on the fan housing wall: the joint sealant, the inside plate with its seal housing, the ring stack, and the outside plate that presses the stack. Dash-dot lines show how the nuts run onto the mounting rods. An inset at the upper right shows the same seal assembled.

The ten parts are the shaft, fan housing wall, threaded mounting rods, 1/8-inch NPT pipe plug, PTFE joint sealant, inside plate with seal housing, carbon yarn packing, Graphoil split ring, Teflon lantern ring and outside plate with retaining ring. On a wide screen a label column with leader lines sits to the right of the drawing; on a narrow screen the labels move below it as a numbered list. The three rings of the stack are small, so their markers sit just below the stack with a short pointer to each ring.

The quiz describes each part by its job or material ("Select the ring that lets purge gas reach the shaft.") instead of naming it, in a shuffled order. You get two attempts per prompt. The first wrong answer shows a hint about where to look; the second reveals the part and counts as missed. Mastery is 8 of 10 correct on the first attempt. Explore mode is never scored.

How to Use¶

Explore mode (the starting mode). Point at a numbered marker, or Tab to it, to see the part's name and description in the panel below the drawing. Click it (or press Enter) to open it; opened parts get a ✓ in the label list and the counter shows how many of the 10 you have visited. Clicking a name in the label list opens that part too.
Quiz mode. Press Quiz. The labels and leader lines disappear and a prompt describes one part:
- Correct: "✓ Correct:" with the part name and its description; the marker turns green with a ✓ badge and its label comes back.
- Wrong on the first attempt: "✗ Not quite.", the name of the part you picked, and a hint. The hint never names the answer.
- Wrong on the second attempt: the answer is marked "Answer" and named, and the prompt counts as missed.
Press Next prompt after each answer. The toolbar shows "Parts correct: n of 10".
After the tenth prompt, the summary shows your first-attempt score, whether you reached mastery (8 of 10), and each missed prompt with its answer. Retry missed practises only the misses (not scored), Start over reshuffles and resets the score, and Back to explore returns to the labels.

Keyboard: Tab moves through the markers in number order and then the buttons; Enter or Space selects a marker. After an answer, focus moves to Next prompt, so Enter goes on.

Data label: "Drawing: FanPedia, Twin City Fan, p. 155", shown under 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/ch16-stuffing-box-seal-overlay/main.html"
        height="858px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan¶

Learning Objective¶

The learner will identify the ten labeled parts of a stuffing box shaft seal with gas purge on an exploded view, given each part's job or material (Bloom: Remember, verb: identify).

Audience¶

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

Duration¶

10-15 minutes

Prerequisites¶

Chapter 16, sections "Shaft Seals" (what a shaft seal does and how every seal assembly mounts to the housing), "Carbon Ring Seals" (the lantern ring and purge on the double carbon ring) and "Stuffing Box Seals".

Activities¶

Explore (4 min): Open all ten parts. Sort them aloud into what is already on the fan (shaft, fan housing wall, threaded mounting rods), what holds and presses the packing (PTFE joint sealant, inside plate with seal housing, outside plate with retaining ring), the ring stack (carbon yarn packing, Graphoil split ring, Teflon lantern ring) and the purge connection (1/8-inch NPT pipe plug).
Trace the purge (2 min): Start at the yellow plug on the seal housing and say where purge gas goes once the customer's line replaces it. Which ring must sit under the purge hole, and why?
Quiz (5 min): Switch to quiz mode and find all ten parts from their jobs without going back to explore mode.
Review (3 min): Read the missed list, open those parts in explore mode, then press Start over for a new order. Then try the Shaft Seal Identifier to tell this seal apart from the other types.

Common Misconceptions Addressed¶

The stuffing box ships ready to connect to a purge line: it ships with a 1/8-inch NPT pipe plug in the purge hole, and the customer-supplied purge line replaces the plug in the field.
All the rings in the stack are the same packing: in Twin City Fan's design the outer rings are carbon yarn packing, the inner rings are Graphoil split rings, and the Teflon lantern ring is a spacer at the purge hole, not packing.
The seal is tightened once at the factory: because the packing is compressed against the shaft by the outside plate on the threaded mounting rods, it can be retightened to take up wear.

Assessment¶

First-attempt score shown in the summary as "First-attempt score: n of 10"; mastery is 8 of 10 on the first attempt.
Pointing at markers and opening infoboxes in explore mode is exploration, not evidence.
Follow-up question: an order line reads "Graphoil Stuffing Box" without "With Purge". Which parts on this drawing would not ship?

References¶

FanPedia: The Fan & Blower Encyclopedia (PDF) - Twin City Fan; p. 155 is the stuffing box type shaft seal with gas purge used here, and pp. 152-154 cover the gas purge seals.
FanPedia online - Twin City Fan's online version of the encyclopedia.
Chapter 16: Bearings, Shafts and Shaft Seals - the section "Stuffing Box Seals", where this MicroSim is embedded, and the section "Shaft Seals".
Chapter 17: Bearing Details, Lubrication and Pedestals - the section "Gas Purge Seals" explains how the lantern ring and purge gas keep process gas in.
Shaft Seal Identifier - classifies a shaft seal into one of seven FanPedia seal types from its parts, materials or order-line name.