Boiler Control Systems Quiz
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Questions and Answers

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?

    <p>Return combustion airflow to low fire</p> 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?

    <p>To stabilize the pilot flame</p> 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?

    <p>Boiler pressure</p> Signup and view all the answers

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

    <p>To clear any remaining combustion gases</p> 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?

    <p>The system goes into standby mode</p> Signup and view all the answers

    Which component shuts off the burner in the described scenario?

    <p>Permissive switch</p> Signup and view all the answers

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

    <p>Steam pressure reaching operating control set point</p> Signup and view all the answers

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

    <p>Repeats the startup sequence</p> Signup and view all the answers

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

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

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

    <p>Closes all SSOVs and locks itself out.</p> Signup and view all the answers

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

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

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

    <p>It initiates a safety shutdown and lockout.</p> Signup and view all the answers

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

    <p>Oil-fired boilers.</p> 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?

    <p>&quot;Call for heat.&quot;</p> 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?

    <p>Opens the main gas SSOV.</p> Signup and view all the answers

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

    <p>The primary controller will retry ignition</p> 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?

    <p>Opens the main SSOV</p> 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?

    <p>Begin the PTFI cycle</p> 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?

    <p>Boiler pressuretrol</p> Signup and view all the answers

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

    <p>Lockout</p> Signup and view all the answers

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

    <p>One</p> Signup and view all the answers

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

    <p>'Permissives' and pre-ignition interlocks must be satisfied</p> Signup and view all the answers

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

    <p>Safety shutdown and lockout</p> Signup and view all the answers

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

    <p>Safety shutdown and lockout</p> 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?

    <p>Activates ignition transformer and fuel oil SSOV</p> Signup and view all the answers

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

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

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

    <p>Low combustion air pressure fuel cut-off switch</p> Signup and view all the answers

    What initiates the boiler ignition sequence?

    <p>Closing the main electrical disconnect switch</p> Signup and view all the answers

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

    <p>At least 60% of the high-fire airflow</p> Signup and view all the answers

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

    <p>Main SSOV</p> Signup and view all the answers

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

    <p>Pilot flame</p> Signup and view all the answers

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

    <p>To reset limit controls</p> Signup and view all the answers

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

    <p>Verifying combustion air requirements</p> Signup and view all the answers

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

    <p>To indicate additional power sources needed</p> 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?

    <p>Shut the pilot SSOV and lock out the burner system</p> Signup and view all the answers

    During which stage does the controller determine power quality?

    <p>Initiate</p> Signup and view all the answers

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

    <p>The primary controller locks out</p> Signup and view all the answers

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

    <p>The main SSOVs close</p> Signup and view all the answers

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

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

    When does the pilot trial for ignition period begin?

    <p>When the safe start check is complete</p> Signup and view all the answers

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

    <p>Pilot flame not proven within 10 seconds</p> Signup and view all the answers

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

    <p>Begins a safe start check looking for a flame</p> Signup and view all the answers

    What is the role of permissive switches during BMS operation?

    <p>Monitor elements of the safety circuit</p> Signup and view all the answers

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

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

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