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Quiz: Advanced Arrangements and Configuration Variants

Test your understanding of arrangement variants, plug and plenum codes, swingout and clamshell construction, and motor position rules with these review questions.

1. How does FanPedia describe Arrangement 8?

  1. A belt driven fan with the motor mounted inside the bearing pedestal
  2. A direct drive fan with the impeller mounted on the motor shaft
  3. A belt driven fan with the motor on a slide base on the side of the pedestal
  4. A direct drive, overhung fan whose Arrangement 1 pedestal is extended to carry the motor, joined by a flexible coupling
Show Answer

The correct answer is D. FanPedia calls Arrangement 8 "a modified version of Arrangement 1 used for direct drive." The pedestal is extended to carry the motor, and a flexible coupling joins the motor shaft to the fan shaft. Because the fan keeps its own shaft and two bearings, the impeller does not hang on the motor bearings. Option A is Arrangement 10, option B is Arrangement 4, and option C is Arrangement 9.

Concept Tested: Arrangement 8

See: Arrangement 8

2. A specification asks for a "vent set." Which arrangement and size range is it asking for?

  1. Arrangement 10, Class I and II fans, sizes 122 through 365
  2. Arrangement 9, any class, sizes 402 and larger
  3. Arrangement 4, Class III fans, sizes 122 through 365
  4. Arrangement 1P plug fans of any size
Show Answer

The correct answer is A. FanPedia states that for Class I and II fans, sizes 122 through 365, Arrangement 10 units are commonly referred to as ventilating sets, and it refers readers to TCF Catalog 600 for details. Arrangement 10 is a compact, belt driven package with the motor inside the bearing pedestal and no motor position to choose. The other options pair the trade name with the wrong arrangement or size range.

Concept Tested: Ventilating Set

See: Ventilating Set

3. What is the key difference between a swingout fan and a clamshell fan?

  1. Swingout fans are axial only, while clamshell fans are housed centrifugal only
  2. Clamshell fans require removing the ductwork, while swingout fans do not
  3. In a swingout fan the rotor swings out on the door; in a clamshell fan the casing opens while the rotor stays in place
  4. Swingout fans are always direct drive, while clamshell fans are always belt driven
Show Answer

The correct answer is C. The chapter frames the difference as what moves when the door opens. A swingout fan mounts the entire impeller, shaft and bearing assembly on a large door that swings out of the housing. A clamshell casing opens around a rotor that stays put. Neither requires removing the ductwork (B). Swingout comes in centrifugal, inline and axial forms (A), and both constructions come in direct and belt drive codes, such as 4S and 9SS or 4CS and 9CS (D).

Concept Tested: Clamshell Fan

See: Clamshell Fan

4. What reasons does FanPedia give for choosing a pedestal plug variant (1P, 4P, 8P or 9P) instead of a wall-hung plug fan?

  1. The P variant protects the motor from high airstream temperatures
  2. The customer's wall may not be sufficient by itself, and mounting to the foundation helps meet lower vibration requirements
  3. The P variant changes the fan from direct drive to belt drive
  4. The P variant removes the need for a fan shaft and bearings
Show Answer

The correct answer is B. FanPedia gives the same reasons for every P variant: it is used where the customer's wall may not be sufficient by itself, and mounting to the foundation makes it better for meeting lower vibration requirements. The P changes only what holds the fan up. It does not change the drive (C), it does not remove shafts or bearings (D), and it does not protect against heat (A). A 4P still carries its impeller on the motor shaft.

Concept Tested: Arrangement 1P Plug; Arrangement 4P Plug; Arrangement 8P and 9P Plug

See: Pedestal Plug Arrangements

5. An Arrangement 9 fan has CCW rotation. Under FanPedia's standard motor position rule, where does the motor go?

  1. Position (L)
  2. Position (R)
  3. Position W
  4. Top Center (TC)
Show Answer

The correct answer is B. FanPedia prints the standard as "CW (L) / CCW (R)" for Arrangements 9 and 9F. The technical descriptions say the motor goes on the left side for CW rotation and the right side for CCW rotation. Position (L) is the CW standard (A). W is one of the four AMCA letters for floor-standing motors on Arrangements 1 and 3 (C). Top Center is used on plenum Arrangements 3HA and 3VA (D).

Concept Tested: Standard Motor Position Rule

See: Standard Motor Position Rule

6. An air handler needs a horizontal, belt driven plenum fan of size 165 with the motor mounted on top of the fan. Which arrangement fits?

  1. 3HS
  2. 3SM
  3. 3VS
  4. 3HA
Show Answer

The correct answer is D. Both 3HS and 3HA mount the motor on top of a horizontal Arrangement 3 plenum fan. Because of the limited belt center range, the NEMA slide base of 3HS is available on sizes 182 and larger only. The heavy-duty adjustable motor base of 3HA is available for all sizes. A size 165 fan with a top-mounted motor is therefore a 3HA. 3SM mounts the motor on the side (B), and 3VS is a vertical unit (C).

Concept Tested: Plenum Arrangements 3HS and 3HA

See: Plenum Arrangements 3HS and 3HA

7. A customer orders an Arrangement 9SS with a left swing. Which rotation, motor position and conduit box must the order carry?

  1. CCW rotation, motor position (R), F2 conduit box
  2. CW rotation, motor position (L), F1 conduit box
  3. CCW rotation, motor position (L), F1 conduit box
  4. Either rotation, with the motor position chosen freely
Show Answer

The correct answer is A. FanPedia's swingout motor position rule ties a 9SS left swing to CCW rotation and motor position (R) only. The fan must have the F2 conduit box for this orientation. Option B is the right swing pairing (CW and L only). On a 9SS, choosing the swing side fixes both rotation and motor position, so options C and D are not allowed. If the duct layout requires CW, switch to a right swing 9SS or to a 9ST.

Concept Tested: Swingout Motor Position Rule

See: Swingout Motor Position Rule

8. A dryer manufacturer needs a large plug fan to recirculate hot air, and the dryer's insulated panel wall cannot carry a large fan and motor. Which choice best fits FanPedia's guidance?

  1. Arrangement 4P, because the pedestal protects the motor from the heat
  2. A wall-hung Arrangement 4 plug fan, because it needs no fan shaft or bearings
  3. Arrangement 9P (or 8P if belts are not allowed), with the fan mounted to grade
  4. Arrangement 4VI, hung from its inlet flange
Show Answer

The correct answer is C. Two separate decisions apply. First the drive: high airstream temperatures may limit Arrangement 4, because the motor bearings carry the impeller, which rules out 4 and 4P. Second the support: the wall is not sufficient, so the fan goes to grade with a P variant. 9P keeps the fan shaft on two bearings outside the enclosure, with speed set by sheaves. 8P is the belt-free alternative. The P itself does not fix a temperature problem (A).

Concept Tested: Arrangement 8P and 9P Plug

See: Arrangement 8P and 9P Plug

9. A belt driven SWSI selection needs a motor too large for an Arrangement 9 pedestal, and the customer requires spring isolators under the fan. What should the engineer quote?

  1. Arrangement 9F, with springs under the extended frame
  2. Arrangement 9H, with the motor moved to an extended side pedestal
  3. Arrangement 1 with a separate isolation base
  4. Arrangement 10, with the motor inside the pedestal
Show Answer

The correct answer is C. Arrangement 9F is FanPedia's answer for a motor too large for the pedestal, but 9F "is not suitable for mounting vibration isolators directly under the fan." When isolators are required, FanPedia advises using an Arrangement 1 fan with a separate isolation base. The chapter's worked example reaches the same conclusion. 9H (B) offers horizontal motor adjustment rather than a larger motor. Arrangement 10 (D) puts the motor inside a compact pedestal.

Concept Tested: Arrangement 9F

See: Arrangement 9F

10. A sales order lists "Arrangement 10, CW, motor position (L)." Why is the motor position entry a problem?

  1. Arrangement 10 has no motor position options; its motor position is unique to the pedestal design
  2. Arrangement 10 requires position (R) for CW rotation
  3. Arrangement 10 uses the inline letters A to H instead of L and R
  4. Arrangement 10 requires an F2 conduit box with position (L)
Show Answer

The correct answer is A. FanPedia lists the Arrangement 10 motor position as "unique to pedestal design (no options)." The motor sits inside the bearing pedestal, so there is nothing to choose and the entry should be removed. The L and R rule (B) applies to the 9 family. The letters A to H are for horizontal inline Arrangement 9 fans (C). The F1/F2 conduit box note applies to position (L) on Arrangements 9 and 9F (D).

Concept Tested: Arrangement 10

See: Arrangement 10

11. A belt driven Arrangement 9 inline fan in a horizontal configuration is floor mounted. Which motor positions are available?

  1. Any of A through H
  2. Only G, H, A, B and C
  3. Only L and R
  4. None, because the motor is centered on the curb cap
Show Answer

The correct answer is B. Inline motor positions A to H run around the casing as seen in the discharge view, with A at the top. A duct or ceiling mounted fan can take any of the eight (A). The floor supports block the lower positions, so a floor mounted fan shows only G, H, A, B and C. L and R are pedestal and frame positions (C). Centering on the curb cap applies to vertical inline fans, which have no specified motor position (D).

Concept Tested: Inline Motor Positions A to H

See: Inline Motor Positions A to H