Deck 7: Hydronic Circulators

Question 1

A flow-check valve, or spring-loaded check valve, needs to be installed in each piping circuit anytime multiple circulators are installed ____.

A) in series
B) proportionally
C) in half unions
D) in parallel

Answer 1

D

Question 2

When designing a piping system, select a circulator that delivers up to ____ more head than required at the desired flow rate.

A) 5%
B) 10%
C) 25%
D) 50%

Answer 2

B

Question 3

The circulator must first be filled with water and purged of most air before it can operate properly.This is called ____.

A) purging
B) compressing
C) priming
D) volumizing

Answer 3

C

Question 4

When two identical circulators are connected in series, the resulting pump curve can be found by doubling the head produced by a single circulator at each flow rate.

Question 5

For a liquid at a given temperature, cavitation occurs anywhere the liquid's pressure ____ its vapor pressure.

A) exceeds
B) is in equilibrium with
C) is compressed by
D) drops below

Question 6

The motor of a wet rotor circulator is totally cooled and lubricated by the system's fluid.

Question 7

An increase in pressure from the inlet to outlet port of an operating circulator is the "evidence" that ____ has been added to the fluid.

A) more volume
B) thermal dynamics
C) antifreeze
D) head energy

Question 8

Always install the circulator so that its inlet is close to the connection point of the system's expansion tank.

Question 9

Within the hydronics industry, the terms pump and circulator are used interchangeably.

Question 10

The circulators used in hydronic systems are technically classified as ____ pumps.

A) pressurized
B) centrifugal
C) nominal
D) rotational

Question 11

The system head loss curve that describes head loss versus flow rate in a specific piping system is not very dependent on fluid properties and temperature.

Question 12

Most circulators used in smaller hydronic systems are designed to be installed with their shafts in a vertical position.

Question 13

The fluid's mechanical energy content is increased as it is accelerated toward the inner edge of the impeller.

Question 14

For a liquid at a given temperature, cavitation occurs anywhere the liquid's pressure drops below its vapor pressure.

Question 15

The most common method of connecting a circulator to piping is with bolted flanges.A special type of flange, known as an isolation flange, contains a built-in ____.

A) water pump
B) thermometer
C) impeller
D) ball valve

Question 16

Circulators with "flat" pump curves should be used when the objective is to maintain a relatively steady pressure differential across the distribution system over a wide range of flow rates.

Question 17

When the rate at which a circulator adds head to the fluid in a piping system equals the rate at which the piping system dissipates this head, the system is in hydraulic equilibrium, and flow rate will ____.

A) remain constant
B) steadily increase
C) occasionally decrease
D) fluctuate only slightly

Question 18

To reduce the number of circulator models needed and still cover a wide range of performance requirements, most circulator manufacturers now offer wet rotor circulators capable of operating at ____ different speeds.

A) three
B) four
C) five
D) many

Question 19

The net positive suction head available (NPSHA) is a precise description of the state of the fluid, within a specific piping system, as it enters the circulator.It includes the effects of temperature, pressure, velocity, and the fluid's ____ into a single number.

A) vapor pressure
B) flow
C) hydraulic equilibrium
D) compressibility

Question 20

The pump curve for two identical circulators connected in parallel is obtained by doubling the flow rate of a single circulator at each head value.