Question 1

The airflow switch is the only positive method of indicating that the fan is actually in operation.

Accepted Answer

The airflow switch is designed to only activate when there is sufficient airflow through the fan, ensuring that the fan is operational. No airflow means the switch will not activate, indicating that the fan is not in operation. Therefore, the statement is true.

Question 2

Airflow switches are sometimes referred to as circular switches.

Accepted Answer

Airflow switches are not referred to as circular switches. They may have circular physical shapes, but their function is to detect the presence or absence of air flow, not to act as a type of switch.

Question 3

Some flow switches sense the flow of liquid and some are made to sense the flow of air.

Accepted Answer

This statement is true. Flow switches can be designed to sense the flow of either liquid or air depending on the intended application.

Question 4

The type of flow switch used in air conditioning systems senses the flow of liquid.

Accepted Answer

The flow switch used in air conditioning systems typically senses the flow of air, not liquid.

Question 5

In a sail switch, when a large amount of airflow passes across the sail, enough force is produced to cause the ____ to operate the contacts of the switch.&#10;A) metal arm&#10;B) bellows&#10;C) spring&#10;D) lever

Accepted Answer

A sail switch typically consists of a metal arm with a sail attached to it. When a large amount of airflow passes across the sail, the force produced causes the metal arm to move, which in turn operates the contacts of the switch. Therefore, the correct choice is A, metal arm.

Question 6

Airflow switches CFS and EFS are operated by the force of air created by the condenser fan or the evaporator fan.

Accepted Answer

Airflow switches CFS (Condenser Fan Switch) and EFS (Evaporator Fan Switch) are designed to detect the flow of air generated by the fans in HVAC systems. When the fans operate, they create a force of air that activates the airflow switches, resulting in the activation of the compressor and other components of the system.

Question 7

Airflow switches are generally used to ensure that ____ before the compressor is permitted to start.&#10;A) a pre-set temperature has been reached&#10;B) air has reached saturation point&#10;C) a pre-set pressure has been reached&#10;D) air is moving across the evaporator coil

Accepted Answer

Airflow switches are used to ensure that air is moving across the evaporator coil before allowing the compressor to start. This is to prevent damage to the system by ensuring there is airflow to absorb heat when the compressor is running.

Question 8

Flow switch contacts are generally normally open and are ____ the coil of the compressor relay.&#10;A) connected in parallel with&#10;B) installed next to&#10;C) connected in series with&#10;D) installed above

Accepted Answer

Flow switch contacts need to interrupt the power supply to the compressor relay when there is low flow or no flow of refrigerant. Placing the switch in series will allow the switch to open the circuit and stop the flow of current to the compressor relay when needed.

Question 9

In one type of flow switch, the switch is actually a ____ that detects the increase in air pressure inside the duct when the blower is in operation.&#10;A) pressure switch&#10;B) toggle switch&#10;C) temperature switch&#10;D) centrifugal switch

Accepted Answer

The statement describes a pressure switch, which is used to detect changes in air pressure when a blower is on. Therefore, option A - pressure switch - is the most appropriate choice. Option B - toggle switch - would not be suitable for detecting changes in air pressure. Option C - temperature switch - and option D - centrifugal switch - are both unrelated to detecting changes in air pressure in a duct.

Question 10

The flow switch is constructed from a snap-action ____.&#10;A) dual switch&#10;B) microswitch&#10;C) dip switch&#10;D) pressure switch

Accepted Answer

A snap-action microswitch is the most common type of switch used in flow switches. They are designed to detect the flow of liquids or gases and trigger an electrical signal when the flow reaches a certain threshold. Dual switches, dip switches, and pressure switches are not typically used in flow sensing applications.

Deck 31: The Flow Switch