Boiler Control Systems Quiz

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What is the first step in the typical sequence of operation for most programming controllers when firing natural gas or oil?

Pre-ignition interlocks (correct)

Start draft fan

Start purge

High airflow

During the programming controller sequence of operation, when does the BMS start the draft fan?

When high airflow is detected

Upon satisfying permissives and pre-ignition interlocks (correct)

After completing the purge

After igniting the pilot

What does the BMS do after detecting high airflow in the programming controller sequence of operation?

Ignite pilot

Return combustion airflow to low fire

Increase fan speed or combustion air damper position to high-fire (correct)

Start purge

In the programming controller sequence of operation, what follows after completing the purge?

Return combustion airflow to low fire Signup and view all the answers

What is the purpose of waiting for up to 10 seconds after igniting the pilot in the programming controller sequence of operation?

To stabilize the pilot flame Signup and view all the answers

Which factor does NOT influence the variations in flame amplifiers, purge timers, and permissives on programming controllers according to the text provided?

Boiler pressure Signup and view all the answers

What is the purpose of the post-purge mentioned in the text?

To clear any remaining combustion gases Signup and view all the answers

In the shutdown sequence described, what happens if the SSOV proof-of-closure switches do not close within 5 seconds?

The system goes into standby mode Signup and view all the answers

Which component shuts off the burner in the described scenario?

Permissive switch Signup and view all the answers

What initiates the programming controller to de-energize the SSOVs in the shutdown sequence?

Steam pressure reaching operating control set point Signup and view all the answers

If all permissives and pre-ignition interlocks are satisfied, what action does the programming controller take?

Repeats the startup sequence Signup and view all the answers

What happens when a limit switch opens during operation of the burner?

The burner conducts a 15-second post-purge and re-enters standby mode. Signup and view all the answers

What does the programming controller do in case of a safety shutdown and lockout?

Closes all SSOVs and locks itself out. Signup and view all the answers

During which period would an airflow proving switch opening lead to a safety shutdown?

During the PILOT TRIAL-FOR-IGNITION PERIOD (PTFI). Signup and view all the answers

What is the action of the BMS in case of detecting an internal fault?

It initiates a safety shutdown and lockout. Signup and view all the answers

Which type of boilers may use stack temperature relays to detect flame failure?

Oil-fired boilers. Signup and view all the answers

What is the condition referred to as when the operating control initiates a startup in natural draft gas-fired boilers with intermittent pilots?

"Call for heat." Signup and view all the answers

What action does the primary controller take after the pilot flame is established in natural draft gas-fired boilers?

Opens the main gas SSOV. Signup and view all the answers

What happens if the pilot does not light within 15 to 90 seconds?

The primary controller will retry ignition Signup and view all the answers

What does the primary control system do when the operating steam pressure or water temperature reaches the desired preset value?

Opens the main SSOV Signup and view all the answers

In case of a main flame failure during operation, what is the immediate action taken by many primary controls?

Begin the PTFI cycle Signup and view all the answers

What triggers the activation of the motor driving the draft fan and fuel oil pump in small mechanically-atomized packaged oil burners?

Boiler pressuretrol Signup and view all the answers

What is the result if the programming control detects an ignition failure during boiler startup?

Lockout Signup and view all the answers

How many pilot ignition retry attempts are usually permitted by primary controls?

One Signup and view all the answers

What must occur before a steam or hot water boiler can be started by its programming controller?

'Permissives' and pre-ignition interlocks must be satisfied Signup and view all the answers

If the main burner goes out during the run period, what is the next step?

Safety shutdown and lockout Signup and view all the answers

What action does the primary controller take if pilot is not established on the second attempt?

Safety shutdown and lockout Signup and view all the answers

What does a BMS do in small mechanically-atomized packaged oil burners when a call for heat is signaled?

Activates ignition transformer and fuel oil SSOV Signup and view all the answers

What must be done if the boiler is gas-fired, according to the text?

Ensure the fuel pressure is below the cutout point of the high gas pressure cut-off switch. Signup and view all the answers

What should be open if the boiler is so configured and requires low combustion air pressure?

Low combustion air pressure fuel cut-off switch Signup and view all the answers

What initiates the boiler ignition sequence?

Closing the main electrical disconnect switch Signup and view all the answers

What is required to be established before the programming controller starts counting the purge?

At least 60% of the high-fire airflow Signup and view all the answers

Which component opens slowly after allowing 10 seconds for the pilot flame to be established?

Main SSOV Signup and view all the answers

What does the flame detector sense after allowing 10 seconds for pilot flame establishment?

Pilot flame Signup and view all the answers

Why is it important to have manual resets on the cut-offs?

To reset limit controls Signup and view all the answers

'Any combustion air damper or air supply interlocks must be satisfied.' What does this statement imply?

Verifying combustion air requirements Signup and view all the answers

'Often, draft fans have a separate electrical feed.' Why is this highlighted in the text?

To indicate additional power sources needed Signup and view all the answers

What action does the BMS take if the pilot is of inadequate strength or too small to reliably light off the main burner?

Shut the pilot SSOV and lock out the burner system Signup and view all the answers

During which stage does the controller determine power quality?

Initiate Signup and view all the answers

What happens if the poor voltage conditions persist for more than 4 minutes?

The primary controller locks out Signup and view all the answers

What occurs during the Main Flame Trial for Ignition (MTFI) period?

The main SSOVs close Signup and view all the answers

If a permissive switch opens during the run period, what action does the BMS take?

Shut off the SSOVs and conduct a post-purge of the furnace Signup and view all the answers

When does the pilot trial for ignition period begin?

When the safe start check is complete Signup and view all the answers

What triggers a safety shutdown and lockout according to the text?

Pilot flame not proven within 10 seconds Signup and view all the answers

What is the significance of the Safe Start stage within the BMS operation sequence?

Begins a safe start check looking for a flame Signup and view all the answers

What is the role of permissive switches during BMS operation?

Monitor elements of the safety circuit Signup and view all the answers

When does the controller enter 'Standby' mode according to the text?

Once there is a call for heat and permissive switches are correct Signup and view all the answers