Flow sensor

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Quick Questions

Shade in the A or B circle for each question.

1. What does a flow sensor measure?

A How much liquid or gas moves past a point in a given time

B How hot the liquid or gas is

2. Which data does a flow sensor capture?

A Flow rate, such as litres per minute

B Brightness of light in a room

3. Which system is most likely to use a flow sensor?

A A burglar alarm that detects someone walking into a room

B A water meter measuring how much water a house uses

4. A farmer wants to know how much water an irrigation system delivers to a field. Which sensor should be used?

A Flow sensor

B Magnetic field sensor

5. Is a flow sensor an input device or an output device?

A Output device, because it shows the flow on a screen

B Input device, because it sends data to the processor

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1flow sensor		AA flow sensor is an input device that measures flow. It does not move the fuel. A pump or valve is an actuator that controls the flow.
2flow rate		BIF flow_sensor > 0 THEN add_to_total
3A water meter uses a flow sensor to record how much water a household uses		CIF flow_rate < 10 THEN sound_alarm
4An irrigation system uses a flow sensor to check that enough water reaches the crops		DA flow sensor measures how much liquid or gas moves past a point in a set time, not its temperature. A temperature sensor measures temperature.
5A flow sensor measures the temperature of a liquid in a pipe		EThe data a flow sensor captures: the volume of liquid or gas passing a point each second or minute
6A flow sensor is an output device that pumps fuel through a pipeline		FAn input device that measures how much liquid or gas moves past a point in a set time

Definitions

flow sensor

Fill in the Blanks

Complete each line of code by filling in the missing parts.

// Flow sensor in a water meter _____ flowRate

IF flowRate _ 5 THEN OUTPUT "Low flow in pipeline" ENDIF

litresUsed ← flowRate _ minutes

IF flowRate > 20 THEN OUTPUT "Close irrigation valve" _____

______ "Fuel used: ", litresUsed

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A flowRate ← 12

B minutes ← 5

C litres ← flowRate * minutes

D OUTPUT flowRate

Question 2

A total ← 0

B REPEAT

C total ← total + READ(flow)

D UNTIL total <= 100

E OUTPUT "Close valve"

Question 3

A flow ← READ(fuelFlow)

B IF flow = 0

C OUTPUT "No fuel moving"

D ENDIF

Question 4

A inFlow ← READ(sensorA)

B outFlow ← READ(sensorB)

C IF inFlow < outFlow THEN

D OUTPUT "Possible leak"

E ENDIF

Question 5

A WHILE tankFilling = TRUE

B flow ← READ(levelSensor)

C total ← total + flow

D ENDWHILE

Answer Key

Flow sensor

Section A: Quick Questions

A — How much liquid or gas moves past a point in a given time

A — Flow rate, such as litres per minute

B — A water meter measuring how much water a house uses

A — Flow sensor

B — Input device, because it sends data to the processor

Section B: Match the Pairs

flow sensor → An input device that measures how much liquid or gas moves past a point in a set time

flow rate → The data a flow sensor captures: the volume of liquid or gas passing a point each second or minute

A water meter uses a flow sensor to record how much water a household uses → IF flow_sensor > 0 THEN add_to_total

An irrigation system uses a flow sensor to check that enough water reaches the crops → IF flow_rate < 10 THEN sound_alarm

A flow sensor measures the temperature of a liquid in a pipe → A flow sensor measures how much liquid or gas moves past a point in a set time, not its temperature. A temperature sensor measures temperature.

A flow sensor is an output device that pumps fuel through a pipeline → A flow sensor is an input device that measures flow. It does not move the fuel. A pump or valve is an actuator that controls the flow.

Section C: Definitions

flow sensor — An input device that measures how much liquid or gas moves past a point in a set time (the flow rate). Used in water meters, fuel systems, pipelines and irrigation.

Section D: Fill in the Blanks

// Flow sensor in a water meter
INPUT flowRate

IF flowRate < 5 THEN
  OUTPUT "Low flow in pipeline"
ENDIF

litresUsed ← flowRate * minutes

IF flowRate > 20 THEN
  OUTPUT "Close irrigation valve"
ENDIF

OUTPUT "Fuel used: ", litresUsed

Section E: Spot the Error

D — The water meter should output the total volume used (litres), not the flow rate. Line 4 should be OUTPUT litres.

D — The irrigation loop should run until the total water reaches 100. With <= the loop would stop straight away. It should be UNTIL total >= 100.

B — An IF statement needs THEN at the end of the condition. It should be IF flow = 0 THEN.

C — A pipeline leak is suspected when more liquid flows in than flows out. The comparison is reversed. It should be IF inFlow > outFlow THEN.

B — A level sensor measures how high the liquid is, not how much moves past a point. To get flow data you must read the flow sensor: READ(flowSensor).