Attachment A - Device List.docx

Water Level Control Devices

1. Low Water Cut-Off

A. Purpose: Automatically shuts down the boiler's burner when the water level drops below a predetermined safe point, preventing potential damage from operating with too little water (also known as "dry firing") by cutting off the fuel supply when necessary; essentially acting as a safeguard against low water conditions.

B. Recommended set point: 2-6 inches below the normal operating water level.

C. Potential hazards due to failure: can lead to the boiler overheating due to lack of water, potentially causing severe damage like warped metal components, cracked tubes, and in extreme cases, a boiler explosion, putting lives and property at risk.

D. Quantity: 1

2. Low Water Alarm

A. Purpose: Required to shut down the boiler in the event of a lack of water in the boiler. Low level may be caused by: A feedwater shortage in the feed tank.

B. Recommended set point: Slightly above the level where the boiler would automatically shut off due to a low water cut-off, providing operators time to address the dropping water level before a complete shutdown occurs.

C. Potential hazards due to failure: Boiler tube damage or catastrophic failure of your boiler can occur. When heat from hot combustion gasses flows into the boiler during low water conditions (aka dry firing) the following may occur: Hot spots and metal discoloration. Warping of metal walls and or boiler tubes.

D. Quantity: 1

3. High Water Alarm

A. Purpose: High water level may be an indication of condensate transfer pump failure that could lead to low water condition in the feedwater deaerator and in the boilers. There may be a failure of make-up water controls.

B. Recommended set point: 4 inches below overflow level and 2/3 of tank height.

C. Potential hazards due to failure: Feedwater deaerator running dry and, consequently, boiler feed pumps running dry will cause overheating and damage to pumps and potential for plant shut down. Failure of make-up water controls (in open position) could lead to significant cost from waste of water and condensate from the tank overflow if this occurs over a long time period.

D. Quantity: 1

4. Low Water Auxiliary Probe

A. Purpose: A secondary safety mechanism, designed to shut off the boiler's fuel supply in the event that the water level drops dangerously low, even if the primary low water cutoff fails, providing an extra layer of protection against potential damage from running with insufficient water.

B. Recommended set point: Water in the boiler must be maintained at the normal operating water level (NOWL). Low water cutoff switches are generally 2-6 inches below the NOWL.

C. Potential hazards due to failure: Failures can result in boiler tube damage or catastrophic failure of your boiler! When heat from hot combustion gasses flows into the boiler during low water conditions (aka dry firing) the following may occur: Hot spots and metal discoloration, warping of metal walls and/or boiler tubes.

D. Quantity: 1 (for the entire boiler plant).

5. Purge Timer

A. Purpose: A device that controls the duration of a “purge cycle”, which is a period where the boiler’s combustion chamber is filled with air before ignition, effectively removing any flammable gases that might be present and ensuring safe startup by preventing potential explosions when the burner is lit; essentially, it allows for a controlled expulsion of old air before new fuel is introduced.

B. Recommended set point: The time it takes to purge a boiler depends on several factors, including the fuel type, duct design, and guidance from the original equipment manufacturer. Typical purge times range from 5 to 18 minutes.

C. Potential hazards due to failure: Combustion chamber may not adequately purge causing ignition problems or incomplete combustion; no purge cycle at all causing an increase in gas build up or an excessively long purge cycle causing unnecessary waste.

D. Quantity: 1 (for the entire boiler plant).

Pressure Containment

1. Relief Valves

A. Purpose: Protects the boiler from excessive pressure build-up by automatically opening to release excess pressure when it reaches a dangerous level, preventing potential explosions or damage to the system.

B. Recommended set point: At or slightly below the boiler’s Maximum Allowable Working Pressure (MAWP), typically with a pressure differential of at least 10 psi or 25% of the operating pressure above the normal operating pressure of the boiler, ensuring the valve opens before excessive pressure builds up.

C. Potential hazards due to failure: Explosions due to excessive pressure build-up, scalding injuries from hot water release, property damage from flooding caused by excessive water discharge and system malfunctions due to uncontrolled pressure fluctuations.

D. Quantity: 1 (3 per boiler for the entire boiler plant)

1. High Steam Pressure Limit Switches

A. Purpose: Automatically shuts of the boiler system when pressure reaches a pre-determined high level, preventing potential damage to equipment by acting as a protective mechanism against excessive pressure build-up.

B. Recommended set point: Typically 10-20 PSI higher than the normal operating pressure of the boiler to ensure a safety buffer to shut off the burner before dangerously high pressure is reached, while still allowing for pressure fluctuations during operation.

C. Potential hazards due to failure: Overheating of the system due to lack of automatic shut-off when pressure reaches unsafe levels, potentially causing damage to the equipment, fire risks, and carbon monoxide exposure.

D. Quantity: 1

3. High Steam Pressure Cutout Manual Reset

A. Purpose: Safety feature on a steam boiler that automatically shuts off the boiler when steam pressure reaches a dangerously high level, requiring a manual reset button to be pressed by an operator to restart the boiler, ensuring the operator is aware of the high-pressure issue and can address the cause before resuming operation; essentially acting as a last line of defense against excessive pressure.

B. Recommended set point: Typically, 10-20 PSI above the normal operating pressure of the boiler to ensure a safety margin and requires manual intervention to restart the system if the pressure reaches the set point, allowing time to investigate the issue causing the high pressure.

C. Potential hazards due to failure: Continuous operation of the boiler resulting increased steam pressure which could reach a dangerously high level, leading to boiler explosion.

D. Quantity: 1

4. Low Atomizing Media Supply Pressure

A. Purpose: Used to create a finer mist of fuel, leading to a better combustion efficiency by ensuring the fuel is thoroughly mixed with air, especially when dealing with viscous fuels like heavy oil, resulting in cleaner burning and reduced emissions.

B. Recommended set point: Typically, falls in the range of 15 to 30 PSI depending on the specific boiler design and fuel type.

C. Potential hazards due to failure: Flame can be extinguished, leading to a potentially hazardous situation with unburned fuel in the furnace. Additionally, poor combustion can result in increased emissions of pollutants like carbon monoxide.

D. Quantity: 1 (for the entire boiler plant)

5. Low Atomizing Media Burner Pressure

A. Purpose: Creates a fine mist of fuel by mixing it with a low-pressure stream of air or steam, allowing for better combustion efficiency by ensuring the fuel is evenly distributed throughout the combustion chamber, especially when operating at low firing rates or requiring precise heat control.

B. Recommended set point: Typically falls within the range of 10-20 PSIG, depending on the specific boiler design and fuel type.

C. Potential hazards due to failure: Improper atomization resulting in incomplete Combustion, insufficient heating and potential soot buildup within the boiler.

D. Quantity: 1 (for the entire boiler plant)

Fuel Train Safety Devices

1. Low Pressure Fuel Cut-Off Switch

A. Purpose: Safety device to automatically shut off the fuel supply to the burner if the water pressure inside the boiler drops below a safe level, preventing potential damage to the boiler from operating with insufficient water.

B. Recommended set point: 1 to 2 psi below the normal operating pressure of the system, ensuring the boiler shuts off before reaching dangerously low pressure levels; for most low-pressure steam systems, this would translate to a setting around 2 psi on the low-pressure switch C. Potential hazards due to failure: Overheating of the boiler due to low water levels, which could result in boiler tube damage, metal warping, and in extreme cases, a catastrophic boiler explosion; this is because the switch is designed to shut off the fuel supply when water levels drop too low, preventing overheating.

D. Quantity: 1

2. High Pressure Fuel Gas Cut-Off Switch

A. Purpose: A safety device designed to automatically shut off the fuel gas supply to a boiler if the gas pressure exceeds a predetermined safe limit, typically triggered by a faulty regulator, preventing potentially dangerous situations like explosions due to excessive pressure.

B. Recommended set point: Slightly above the normal operating gas pressure of the boiler, ranging from 1.5 to 2 times the normal operating pressure, depending on the boiler.

C. Potential hazards due to failure: Uncontrolled release of high pressure fuel gas, which can result in a gas leak, potential ignition leading to fore or explosion, and potential carbon monoxide buildup if the gas is not properly vented.

D. Quantity: 1

3. Venting Between Automatic Gas Shut-Off Valves

A. Purpose: To Safely release any gas that might leak past the first shut-off valve preventing it from accumulating and potentially igniting further down the line, thus acting as a safety measure to ensure no gas enters the combustion chamber if a primary shut-off valve fails.

B. Recommended Set Point: Typically, at atmospheric pressure.

C. Potential Hazards Due to Failure: Gas leak, leading to a potential explosion or fire due to the buildup of flammable gas in the boiler room, as well as carbon monoxide poisoning from the unburned gas if inhaled.

D. Quantity: N/A

4. Leak Test of Automatic Gas Shut-Off Valves

A. Purpose: To ensure the valve is properly sealing and preventing any gas leaks, which could be extremely dangerous due to the potential of fire or explosion.

B. Recommended Set Point: Typically, at the rated work pressure of the valve, usually slightly higher than the normal operating pressure of the boiler system, allowing for a small margin of safety to accurately detect leaks in accordance with any specific manufacturers instructions and local codes.

C. Potential Hazards Due to Failure: Gas leaking out, which can accumulate in the boiler room and create a flammable atmosphere, leading to fire or explosion if ignited.

D. Quantity: 1 (for the entire boiler plant).

5. Oil Low Atomizing Media Pressure and Differential Pressure Switches

A. Purpose: Safety devices that monitor the pressure of atomizing media (typically air or steam) used to break down the fuel oil into a fine mist for proper combustion, ensuring the burner shuts off if the pressure drops too low, preventing incomplete burning and potential damage to the boiler by allowing anatomized oil to build up.

B. Recommended Set Point: The recommended set point for an Oil Low Atomizing Media Pressure switch on a boiler is typically between 80-100 PSI, while the Differential Pressure Switch should be set at a point where it activates at around 20% of the full atomizing media pressure.

C. Potential Hazards Due to Failure: Incomplete combustion, excessive fuel consumption, potential for furnace “puffs” or explosions, overheating of the boiler and damage to the boiler system due to improper fuel delivery and combustion control when the burner does not receive the necessary signal to adjust fuel flow based on the pressure of atomizing media(typically air or steam) or the pressure differential across the burner nozzle.

6. Automatic Fuel Shut-Off Valve Proof of Closure Switch

A. Purpose: A safety mechanism that verifies the valve is completely closed before the boiler starts up, ensuring that no fuel can flow to the burner unless the shut-off valve is fully shut, preventing potential ignition issues and hazardous situations in case of a malfunction or leak.

B. Recommended Set Point: Between 5 and 10 seconds; allowing enough time to for the valved to fully close while still providing a prompt indication of proper closure in case of a fault, with faster times generally preferred for larger boiler capacities or high-pressure applications.

C. Potential Hazards Due to Failure: Gas leaks, uncontrolled fuel flow to the burner, potential for explosion due to gas build-up in the combustion chamber and carbon monoxide poisoning if the leaked gas isn’t properly vented.

D. Quantity: 1

7. Gas Safety Shut-Off Valve Leak Test

A. Purpose: Ensures the valve is properly sealing and not allowing any gas to leak out when it’s supposed to be closed.

B. Recommended Set Point: The normal operating pressure of the gas line as indicated by the manufacturer’s instructions for the specific valve and boiler system.

C. Potential Hazards Due to Failure: gas leak, resulting in fire, explosion or carbon monoxide poisoning.

D. Quantity: 1

8. Main Gas Vent Valve Leak Test

A. Purpose: Verifies that the valve designed to release excess gas from the gas supply line is functioning properly and not leaking.

B. Recommended Set Point: 75% of the valve’s set pressure.

C. Potential Hazards Due to Failure: Gas leaks into the surrounding area, carbon monoxide poisoning from incomplete combustion, potential explosion due to gas buildup, fire hazards and exposure to harmful fumes.

D. Quantity: 1 (for the entire boiler plant)

9. Pilot Gas Shutoff Valve Leak Test

A. Purpose: Verifies that the valve is properly sealing and not allowing gas to leak out in the event of a malfunction or a shutdown situation.

B. Recommended Set Point: 75% of the valve’s rated working pressure to allow for a thorough check without putting excessive stress on the valve or system components.

C. Potential Hazards Due to Failure: Potential gas leak, fire, explosion and carbon monoxide poisoning.

10. Pilot Gas Vent

A. Purpose: To allow a tiny amount of gas to escape, creating a continuous “pilot light” flame which acts as an ignition source for the main gas burner when the burner needs to heat water.

B. Recommended Set Point: front or side of the boiler, often near the burner assembly.

C. Potential Hazard Due to Failure: Pilot flame will extinguish, yellow or flickering flame, boiler not heating properly even when pilot is lit and unusual noises from the boiler.

D. Quantity: 1 (for the entire boiler plant)

11. Gas Safety Shutoff Valve Proof of Closure

A. Purpose: Mechanism that provides a verifiable signal indicating the valve is fully closed, ensuring that no gas is leaking when the valve is supposed to be shut off.

B. Recommended Set Point: Around 50% of the normal operating gas pressure; this can vary depending on local codes, the size of the burner and the specific valve manufacturer’s specifications (larger burners require a higher proof of closure procedure).

C. Potential Hazard Due to Failure: Significant gas leak, fire, explosion, and carbon monoxide poisoning.

D. Quantity: 1

Burner and Train Safety Devices

1. Flame Scanner

A. Purpose: A safety device that continuously monitors the presence of a flame within the combustion chamber which ensures that the burner is properly ignited and burning fuel. If the flame goes out it will signal the boiler to shut off the fuel supple, preventing a potentially dangerous buildup of unburned gas.

B. Recommended Set Point: Between 2 to 10 microamps.

C. Potential Hazard Due to Failure: Unburned fuel accumulation, gas leaks, potential explosions due to ignition of unburned fuel, carbon monoxide poisoning, and overheating of the boiler.

D. Quantity: 1

2. Low Fire Proving Switch

A. Purpose: A safety feature that ensures the boiler reaches a minimum operating temperature pressure before transitioning to full power (high fire), preventing thermal shock to the boiler by forcing it to initially operate at a low fire setting until conditions are suitable for heat output.

B. Recommended Set Point: Slightly below the desired operating pressure, allowing the burner to initially operate at low fire until the boiler reaches a safe operating pressure before transitioning to full fire; this prevents thermal shock to the boiler by starting at a lower heat output.

C. Potential Hazards Due to Failure: Uncontrolled fuel combustion, excessive heat generation within the combustion chamber, potential for boiler explosion due to fuel buildup, carbon monoxide poisoning from incomplete combustion and damage to the boiler itself.

D. Quantity: 1

3. Flame Failure Response Time

A. Purpose: The designated amount of time a flame sensor will wait before triggering a safety shutdown if it does not detect a flame, essentially acting as a safety mechanism to prevent buildup of unburnt fuel in the combustion chamber by quickly shutting off the gas supply if the flame goes out unexpectedly; this time is crucial to avoid false alarms while still ensuring prompt action in case of a real flame failure.

B. Recommended Set Point: Usually within a few seconds, generally ranging from 1 to 4 seconds depending on the type of flame sensor and boiler design; this means that once the flame is lost, the boiler should shut off the fuel supply within this timeframe as a safety measure.

C. Potential Hazards Due to Failure: Buildup of flammable gas within the combustion chamber, increasing the risk of explosion, carbon monoxide poisoning sue to incomplete combustion, overheating of the boiler components, and potential property damage from a fire if the excess fuel ignites unexpectedly.

D. Quantity: 1

4. Ignition Pilot Flame Failure

A. Purpose: Indicates that the small, constantly burning pilot flame, which is meant to ignite the main gas burner when the boiler is turned on, has gone out, preventing the boiler from producing heat because the main burner cannot be ignited properly.

B. Recommended Set Point: Within 15-20% of the normal operating pressure, as specified by the burner manufacturer.

C. Potential Hazards Due to Failure: Gas leaks, incomplete combustion leading to carbon monoxide production, potential explosions, (especially in older boilers with faulty safety mechanisms), and the risk of fire due to unburned gas accumulating in the combustion chamber.

D. Quantity: 1 (for the entire boiler plant)

5. Combustion Air Pressure Switch

A. Purpose: Monitors the air pressure within the combustion chamber, ensuring there is enough incoming air to support proper combustion, and will shut off the burner if the pressure drops below a safe level.

B. Recommended Set Point: Between 1.5 and 2.5 inches of water column, depending on the specific boiler design and manufacturer’s specifications to ensure adequate air flow for proper combustion while preventing excessive pressure buildup.

C. Potential Hazards Due to Failure: Incomplete combustion, carbon monoxide buildup, potential explosions due to improper fuel-air mixture, and the release of harmful flue gases back into the living space if the switch fails to signal proper airflow, preventing the burner from igniting or shutting off when necessary.

D. Quantity: 1

6. Combustion Air Flow

A. Purpose: Provides the necessary oxygen for complete and efficient burning of fuel, ensuring proper combustion by delivering the right amount of air to mix with the fuel preventing incomplete burning and potential safety hazards like carbon monoxide buildup.

B. Recommended Set Point: 8 cubic feet per minute (CFM) per boiler horsepower (BHP). The total recommended air for combustion and ventilation is 10 CFM per BHP.

C. Potential Hazards Due to Failure: Carbon monoxide poisoning, explosion, soot and carbon deposits, inefficient burning, pollution, flame instability, fire, low water levels, corrosion and heat transfer surface fouling.

D. Quantity: 1

7. Purge Air Flow Proving Switch

A. Purpose: Verifies that a sufficient amount of air is flowing through the combustion chamber during the “purge” cycle before ignition, ensuring that any residual fuel or combustible gases are expelled before the burner is lit, preventing potential explosions.

B. Recommended Set Point: 70% of the maximum required air flow during the purge cycle, with some sources suggesting setting it slightly higher at 80% of the maximum delta P to ensure sufficient air flow before ignition is initiated; however, the exact setting will depend on the specific boiler design and manufacturer's guidelines.

C. Potential Hazards Due to Failure: Incomplete purging of the combustion chamber before ignition, which could result in fuel-air mixture that is too rich, causing a potential explosion hazard, carbon monoxide buildup, or efficient combustion.

D. Quantity: 1

8. Burner Position Switch

A. Purpose: Controls the firing rate of the burner, essentially allowing the operator to select between different levels of heat output depending on the heating demand, often by switching between "high fire" and "low fire" positions to adjust the amount of fuel being burned and the heat generated by the boiler.

B. Recommended Set Point: Around 180*F (82*C), which is considered the standard operating temperature for most hydronic heating systems; however, the exact setting may vary depending on the specific boiler model and system design, so always consult the manufacturer's instructions for the most accurate setting.

C. Potential Hazards Due to Failure: Ignition failure, incomplete combustion, excessive fuel consumption, overheating the boiler, potential for explosions due to unburned fuel buildup, and carbon monoxide poisoning as the burner may not ignite properly or could remain on when it shouldn’t, leading to unsafe conditions.

D. Quantity: 1

9. Forced Draft Motor Interlock

A. Purpose: Prevents the boiler from firing if the forced draft fan, which supplies combustion air to the burner, is not operating properly, ensuring that the burner cannot ignite without sufficient air supply to prevent dangerous fuel buildup and potential explosions.

B. Recommended Set Point: Set slightly positive, around 0.1 to 0.2 inches water gauge (WG), ensuring a slight positive pressure within the furnace to promote a proper combustion and prevent flue gas from leaking back into the combustion chamber.

C. Potential Hazards Due to Failure: Incomplete combustion due to insufficient air supply, which can lead to the build up of flammable gases within the combustion chamber potentially causing a fire or explosion, as well as reduced heating efficiency and increased emissions due to unburned fuel.

D. Quantity: 1

10. Outlet Stack Damper Position Interlock

A. Purpose: Guarantees as much as possible that adequate air flow is present at all firing rates for the boiler.

B. Recommended Set Point: Near the fully closed position (around 90-100% closed) to ensure the damper is almost completely shut before the boiler can fire, preventing excessive draft during the pre-purge cycle and maximizing safety during startup.

C. Potential Hazards Due to Failure: Incomplete flue gas exhaust, buildup of harmful gases like carbon monoxide within the building, potential for explosions due to improper combustion, increased emissions, and damage to the boiler itself.

D. Quantity: 1

11. Forced Draft Damper Wide Open Pre-Purge Proving Switch

A. Purpose: A safety mechanism that ensure a sufficient amount of air is flowing through the combustion chamber before ignition by verifying that the forced draft damper is fully open during the pre-purge cycle, preventing the potential for fuel buildup and dangerous explosions by ensuring proper air exchange before firing the burner.

B. Recommended Set Point: Fully open or 100%; the damper should be completely open during the pre-purge phase to ensure adequate air flow for purging out any combustible gases before ignition.

C. Potential Hazards Due to Failure: Incomplete purging of the combustion chamber before ignition, resulting in a potential for fuel ignition within the furnace without sufficient air, leading to smoke, incomplete combustion, possible flame impingement of the furnace walls, and a potential fuel-rich explosion.

D. Quantity: 1

12. Pre-Purge and Post-Purge Timers

A. Purpose: Pre-purge timers are used to run the combustion air fan for a set period of time before ignition, clearing out any residual gases in the combustion chamber to prevent explosions. Post-purge timers are used for keeping a fan running after the burner shuts off to expel any remaining combustion products and prevent backdrafting to ensure a safe and clean combustion cycle.

B. Recommended Set Point: Between 10 and 30 seconds to allow enough time clear out any residual gases in the combustion chamber before ignition and after shutdown, while not unnecessarily extending the cycle time.

C. Potential Hazards Due to Failure: Explosions due to flammable gas buildup in the combustion chamber before ignition (pre-purge failure), or the release of unburned combustible gases into the flue system after shutdown (post-purge failure), both of which can pose significant safety risks to personnel and equipment.

13. Igniter Timer and Main Flame Ignition Timer

A. Purpose: The ignitor timer controls the duration that the ignitor spark is active to initiate combustion, while the main flame ignition timer sets a specific time window for the main burner to establish a stable flame after the initial ignition spark.

B. Recommended Set Point: For an ignitor timer, it falls within the range of 10 to 20 seconds. The main flame ignition timer should be set between 10 and 15 seconds; however, the exact settings will depend on the specific boiler model and fuel type.

C. Potential Hazards Due to Failure: A failure of the igniter timer and main flame ignition timer on a boiler can lead to potential hazards like gas leaks, delayed ignition causing a small explosion, unburned fuel accumulation, carbon monoxide poisoning, and potential fire risk due to the possibility of gas building up in the combustion chamber without proper ignition when the timers malfunction.

D. Quantity: 1

14. Automatic Fuel Shutoff Valve Closure Time After Main Flame Failure

A. Purpose: To quickly cut off the fuel supply to the burner in case of a flame loss, preventing the potential buildup of flammable gas within the combustion chamber and ensuring safety by minimizing the risk of explosion or fire.

B. Recommended Set Point: between 1 and 5 seconds; however, for high BTU burners exceeding 2,500,000 BTU/hr, the closure time should be set to a maximum of 1 second to ensure rapid safety shut-off.

C. Potential Hazards Due to Failure: Continued fuel flow, leading to potential gas leaks, excessive fuel accumulation in the combustion chamber, potential ignition of the gas mixture upon reignition, and increased risk of fire or explosion; additionally, incomplete combustion due to excess fuel could result in the production of harmful pollutants like carbon monoxide.

D. Quantity: 1

15. Automatic Fuel Shutoff Valve Closure Time After Pilot

A. Purpose: to ensure safety by preventing the buildup of unignited fuel in the combustion chamber if the main burner fails to light properly; this delay allows enough time for the pilot flame to establish itself before the main fuel flow is fully turned on, minimizing the risk of a fuel explosion.

B. Recommended Set Point: between 5 to 10 seconds; however, this can vary depending on the boiler size, fuel type, and manufacturer specifications, with larger boilers potentially requiring slightly longer closure times.

C. Potential Hazards Due to Failure: potential fuel buildup in the combustion chamber, which could lead to a combustion explosion due to the ignition of a large amount of unburned fuel when the main burner ignites; this is particularly dangerous in high-pressure boiler systems D. Quantity: 1 (for the entire boiler plant)

16. Minimum Pilot Flame Test

A. Purpose: to ensure that the pilot flame, a small continuously burning flame, is strong enough to reliably ignite the main burner when needed, while still operating at a low fuel consumption level; essentially checking if the pilot flame is sufficiently stable and present to safely initiate combustion in the boiler without excessive fuel usage.

B. Recommended Set Point: falls within the range of 1.5 to 2 inches in flame height; however, the exact setting will depend on the specific boiler model and manufacturer's instructions.

C. Potential Hazards Due to Failure: A potential buildup of flammable gas within the combustion chamber, which could lead to an explosion if ignition occurs due to a spark or other source, as the safety mechanism designed to shut off gas flow in the absence of a flame is not functioning properly; this can result in serious injury, property damage, and carbon monoxide poisoning.

D. Quantity: 1 (for the entire boiler plant)

17. Control Air Pressure Alarms

A. Purpose: to alert operators when the air pressure used to operate various control functions within the boiler system falls outside of a safe operating range, potentially indicating a problem with the air supply and potentially affecting the boiler's ability to function properly or even posing a safety risk if left unaddressed.

B. Recommended Set Point: slightly below the normal operating pressure of the boiler system, with a differential setting to ensure the alarm triggers before the system experiences significant pressure issues; this can vary depending on the specific boiler design and manufacturer guidelines, but a common practice is to set the alarm at around 5-10% below the normal operating pressure.

C. Potential Hazards Due to Failure: Uncontrolled boiler operation leading to excessive pressure buildup, potential boiler explosions, steam leaks, scalding burns from high-pressure steam, and damage to boiler components due to the inability to monitor and respond to critical pressure changes within the system.

D. Quantity: 1

18. Low Instrument Air Pressure

A. Purpose: to activate safety interlocks or alarms when the pressure drops below a set point, essentially acting as a warning signal that the boiler system might not be operating properly and could require attention to maintain safe and efficient operation; it is primarily used for monitoring and control functions within the boiler system, not as a primary power source for the boiler itself.

B. Recommended Set Point: Boilers that service larger buildings may need more than 12 psi. Those that service two or three-floor homes may need 15 or 18 psi when cold. They may go up to 30 psi when warm. A reading over 30 psi on a boiler is a cause for concern.

C. Potential Hazards Due to Failure: Inaccurate readings on critical gauges, inability to operate safety devices like the low water level cutouts, improper control of combustion air, and ultimately, potential for overheating or damage to the boiler system due to the lack of reliable monitoring and control mechanisms.

D. Quantity: 1 (for the entire boiler plant)

19. Low Oil Pressure

A. Purpose: acts as a safety mechanism to prevent the burner from operating if the oil pressure is too low, which could lead to improper fuel atomization, poor combustion, and potential damage to the boiler by causing oil to pool instead of burning efficiently; essentially, it ensures that the oil is being delivered at a sufficient pressure for optimal burning.

B. Recommended Set Point: Low pressure will cause a boiler to have trouble reaching the right temperature. Ideally, the system will refill itself to 12 psi, but you can do it manually if the pump is down. That will keep the boiler operating until a technician arrives.

C. Potential Hazards Due to Failure: Harm to the heating system. This could include reducing the efficiency of your boiler, making it louder and impacting the amount of hot water you get.

D. Quantity: 1 (for the entire boiler plant)

20. High Oil Pressure

A. Purpose: High oil pressure in a boiler is not the intended purpose, but rather a potential issue; a boiler needs sufficient water pressure to effectively circulate hot water throughout the heating system, and excessively high pressure can be dangerous, potentially causing damage to the boiler or system components due to excessive strain on seals and pipes.

B. Recommended Set Point: A boiler's pressure gauge will usually sit between 1 and 2 bars when it is turned on. The exact recommended pressure level will vary depending on the boiler manufacturer.

C. Potential Hazards Due to Failure: Explosions causing property damage, severe injuries or fatalities, strain on the boiler’s components, leaks, ruptures or mechanical failures.

D. Quantity: 1 (for the entire Boiler Plant)

21. Gas Safety Shutoff Valve Proof of Closure

A. Purpose: A mechanism that provides a verifiable signal indicating the valve is fully closed, ensuring that no gas can leak out when the valve is supposed to be shut off, thus acting as a critical safety feature to prevent gas leaks and potential hazards; it essentially confirms the valve is properly sealed and not partially open.

B. Recommended Set Point: Typically, "fully closed" with a minimal leakage rate, often verified by a dedicated “proof of closure switch” that activates only when the valve is completely shut; specific requirements may vary depending on the boiler size, local codes, and manufacturer specifications, but the key is to ensure the valve is completely closed to prevent gas leaks.

C. Potential Hazards Due to Failure: A gas leak, which could lead to fire, explosion, or carbon monoxide poisoning due to the uncontrolled release of flammable gas into the surrounding area; this is particularly dangerous if the leak goes undetected due to the odorless nature of natural gas.

D. Quantity: 1

22. Oil Safety Shutoff Valve Proof of Closure

A. Purpose: A mechanism that provides a verifiable signal indicating the valve is fully closed, ensuring that no gas can leak out when the valve is supposed to be shut off, thus acting as a critical safety feature to prevent gas leaks and potential hazards; it essentially confirms the valve is properly sealed and not partially open.

B. Recommended Set Point: Typically, "fully closed" with a minimal leakage rate, often verified by a dedicated "proof of closure switch" that activates only when the valve is completely shut; specific requirements may vary depending on the boiler size, local codes, and manufacturer specifications, but the key is to ensure the valve is completely closed to prevent gas leaks.

C. Potential Hazards Due to Failure: A gas leak, which could lead to fire, explosion, or carbon monoxide poisoning due to the uncontrolled release of flammable gas into the surrounding area; this is particularly dangerous if the leak goes undetected due to the odorless nature of natural gas.

D. Quantity: 1

23. Oil Safety Shutoff Valve Proof of Closure

A. Purpose: A mechanism that verifies the valve is completely closed, providing assurance that no oil can flow to the burner, thus acting as a critical safety feature to prevent potential hazards like fuel leaks or uncontrolled combustion in case of a malfunction or emergency shutdown; essentially, it confirms the valve is securely shut before the boiler can be restarted or operated.

B. Recommended Set Point: Within 10% of the boiler’s maximum allowable working pressure. (MAWP), ensuring the valve shuts off effectively at a pressure slightly above the normal operating pressure, providing a safety margin.

C. Potential Hazards Due to Failure: Uncontrolled fuel oil leakage, potential fire risk due to fuel oil spills, potential for boiler overheating due to excessive fuel supply, and potential damage to the boiler itself from over-pressurization; all of which could lead to serious injury, property damage, and environmental contamination.

D. Quantity: 1

24. Low Fire Switch-FD Damper

A. Purpose: A safety feature that ensures the boiler starts up at a low firing rate, preventing thermal shock by gradually warming up the system before reaching full power, thus protecting the boiler from damage by sudden temperature changes; the "FD" refers to the forced draft damper which controls the amount of air supplied to the burner, allowing for precise low-fire operation.

B. Recommended Set Point: Typically, around 140°F (or slightly below the desired operating temperature), which allows the boiler to initially fire at a low rate until it reaches a safe operating temperature before ramping up to full capacity.

C. Potential Hazard Due to Failure: Accumulation of unburned fuel in the firebox which can lead to an explosion, Loss of combustion air from a FD fan causing an accumulation of unburned fuel in the firebox which can lead to an explosion.

D. Quantity: 1

Additional Equipment and Devices

1. Loop Controllers for Combustion Control and Feedwater Systems

A. Purpose: used to automatically maintain desired operating parameters like steam pressure and water level within the boiler drum by adjusting fuel flow, combustion air, and feedwater flow based on real-time sensor readings, ensuring efficient and safe operation of the boiler by constantly monitoring and correcting deviations from set points through feedback loops.

B. Recommended Set Point: It should be set near the desired steam pressure operating point, while the feedwater system setpoint should be set at a slightly lower water level within the steam drum, typically aiming for the mid-range of the level transmitter span, to ensure adequate water supply without excessive carryover; always consult the boiler manufacturer's specific guidelines for optimal settings.

C. Potential Hazards Due to Failure: Overheating of the boiler due to improper fuel-air ratio or low water levels, potential explosions from excessive pressure buildup, damage to boiler components from thermal stress, steam carryover into the steam line, and reduced system efficiency due to inefficient combustion; all of which can result in safety risks and operational disruptions.

D. Quantity: 1 (for the entire boiler plant)

2. Flame Safety Equipment Including Scanners, Amplifiers, Controllers and Displays

A. Purpose: Used to continuously monitor the presence of a flame within the combustion chamber, ensuring safe operation by triggering a shutdown sequence if the flame is lost or unstable, preventing potential hazards like fuel leaks or explosions; essentially, it acts as a safety mechanism to verify proper combustion is occurring at all times.

B. Recommended Set Point: to ensure prompt detection of flame loss and immediate fuel shut-off, typically with a low flame signal level on the scanner and a corresponding high alarm level on the amplifier, while considering the specific burner design and fuel type, with additional monitoring features like burner cycle displays and diagnostic annunciation for troubleshooting; always follow manufacturer guidelines and local safety regulations.

C. Potential Hazards Due to Failure: TBD D. Quantity: 1 (for the entire boiler plant)

3. Control Panel Recording, Annunciation and Indicating Equipment

A. Purpose: The control system is responsible for maintaining the proper water level, pressure, and temperature inside the boiler, as well as controlling the firing rate of the burner to match the demand for steam or hot water.

4. Misc. Control Panel Equipment Including Relays, Timers, I/P’s and Power Supplies

A. Purpose: A modern boiler room requires numerous control systems to ensure a reliable and trouble free operation, some of them governed by Regulations. Diverse regulations prevail in some countries although there is a increase trend to homogenize them into International Regulations.

5. Differential Pressure (DP) and Gauge Pressure Transmitters

A. Purpose: In a boiler, Differential Pressure (DP) transmitters are primarily used to monitor the flow rate of water or steam by measuring the pressure difference between two points in the system, typically before and after a flow restriction, while Gauge Pressure Transmitters measure the absolute pressure within the boiler, providing crucial information for safe and efficient operation by indicating potential issues like low water level, clogged pipes, or excessive pressure build-up.

B. Recommended Set Point: Typically falls within a range of 10-20 inches of water column (wc), depending on the specific boiler design and operating conditions, while the gauge pressure transmitter should be set to the nominal operating pressure of the boiler, usually around 100-150 psi depending on the system.

C. Potential Hazards Due to Failure: Inaccurate fuel/air ratio control, potential for boiler overheating or flame instability, unsafe operating conditions due to lack of critical pressure monitoring, potential for boiler damage due to uncontrolled pressure fluctuations, and in extreme cases, potential for explosions if the failure goes undetected and leads to extreme pressure conditions; all stemming from the inability to accurately monitor and regulate crucial boiler pressures, potentially impacting safety and operational efficiency.

D. Quantity: 1 (for the entire boiler plant)

6. Flow Meters

A. Purpose: Used to measure the rate at which water or steam is flowing through the system, providing crucial information for monitoring boiler efficiency, identifying potential issues like leaks, and ensuring optimal combustion by accurately regulating the fuel-to-air ratio, ultimately helping to minimize energy waste and emissions.

B. Recommended Set Point: It depends on the specific system and climate, but generally falls within the range of 120-160 degrees Fahrenheit for low-temperature settings and 180-200 degrees Fahrenheit for high-temperature settings; aiming for a lower flow rate can improve energy efficiency, but be sure to maintain enough flow to adequately heat your home.

C. Potential Hazards Due to Failure: Inaccurate readings of fluid flow, impacting production processes, causing potential waste of materials, incorrect billing due to inaccurate measurements, inefficient system operation, and in some cases, safety concerns depending on the application, all due to the system not receiving the correct information about the fluid flow rate.

D. Quantity: 1

7. Oxygen Analyzers

A. Purpose: To continuously monitor the amount of oxygen in the flue gas, allowing operators to optimize combustion efficiency by adjusting the air-fuel ratio and ensuring complete combustion, which minimizes fuel waste and harmful emissions while maintaining safe operating conditions; essentially, it helps to achieve the best possible fuel burn by monitoring the level of excess air in the combustion process.

B. Recommended Set Point: 3% O2” is required as a benchmark for the oxygen content in the flue gas. This is because the boiler will operate at various O2 levels, and the air district needs to normalize the measurements. Sometimes, emission limits are referenced with different O2 levels for equipment in the same plant.

C. Potential Hazards Due to Failure: An excess of oxygen in the combustion process can result in incomplete combustion and increased emissions, while a lack of oxygen can cause carbon monoxide (CO) emissions and other safety hazards.

8. Control Valves and Actuators

A. Purpose: A control valve regulates the flow of a fluid or gas by partially opening or closing, while an actuator is the device that physically moves the valve to the desired position based on a signal from a control system, essentially allowing precise control over the flow rate by adjusting the valve's opening degree; together, they enable precise control of fluid flow in industrial processes.

B. Recommended Set Point: For most control valves and actuators is typically around the mid-range of their operating signal, usually represented as a 50% open position when using a standard 3-15 PSI pneumatic signal, meaning the set point would be around 9 PSI; this allows for optimal control in both opening and closing directions, providing flexibility to adjust flow as needed.

C. Potential Hazards Due to Failure: The failure of a valve can lead to a sudden release of pressure or fluid, resulting in accidents, injuries, and damages to equipment. Conduct regular maintenance and inspections to prevent valve failure by detecting and addressing potential issues before they escalate.

D. Quantity: 1 (for the entire boiler plant)

9. Low Water Cutout and Alarm Systems

A. Purpose: A safety device designed to automatically shut off the boiler's fuel supply and trigger an alarm when the water level drops below a safe minimum, preventing potential damage to the boiler from overheating caused by a lack of water.

B. Recommended Set Point: Low water cutoff switches are generally 2-6 inches below the NOWL.

C. Potential Hazards Due to Failure: Overheating of boiler components, warping or cracking of metal walls and tubes, potential boiler explosions due to "dry firing" where the heating elements are exposed without water cooling, and catastrophic damage to the boiler system; essentially, if the water level drops too low without the system shutting off the heat source, the exposed metal parts can become extremely hot and potentially fail due to stress and catastrophic damage to the boiler system.

D. Quantity: 1 (for the entire boiler plant)

10. Blow Down Water Filled Sensing Lines for DP and Pressure Transmitters

A. Purpose: To periodically purge the sensing lines of any accumulated solids or condensate, ensuring accurate pressure measurements by maintaining a clear flow of water through the lines; this helps prevent inaccurate readings caused by buildup that could obstruct the pressure sensing mechanism B. Recommended Set Point: The recommended set point for blow down water filled sensing lines on a boiler's DP and pressure transmitters typically falls within the range of 10-20 psi (pounds per square inch), though this can vary depending on the specific boiler design, operating pressure, and water quality, with higher pressures potentially requiring a slightly higher set point for effective cleaning.

C. Potential Hazards Due to Failure: Inaccurate water level readings, leading to potential low water level conditions, which could result in boiler damage due to overheating, steam generation issues, or even a boiler explosion in extreme cases; additionally, incorrect pressure readings could disrupt control systems and impact overall boiler efficiency, potentially causing safety concerns and operational disruptions.

D. Quantity: 1 (for the entire boiler plant)

11. Calibrate Oxygen Analyzers

A. Purpose: To ensure accurate measurement of the oxygen level in the flue gas, which is crucial for optimizing combustion efficiency, reducing emissions, and maintaining safe operating conditions by allowing operators to precisely adjust the air-to-fuel ratio based on real-time data about the oxygen content in the exhaust gases.

B. Quantity: 1

12. Calibrate DP and Pressure Transmitters

A. Purpose: To ensure accurate measurement of critical parameters like water level within the boiler drum, which is vital for safe and efficient operation; by calibrating these transmitters, you verify that the readings are correct and can rely on them to maintain the proper water level, preventing potential damage from either too low or too high levels.

B. Recommended Set Point: The transmitter should be calibrated 0 to 1100 mmWC to measure liquid levels of 0 mm to 1000 mm. A somewhat more complex application is illustrated in Figure 2. In this application, for process reasons, we need to take the measurement from 200 mm to 1000 mm above the nozzle.

C. Potential Hazards Due to Failure: Inaccurate water level monitoring, which could result in low water level causing boiler damage, high water level leading to water carryover and potential steam line damage, inefficient boiler operation, safety concerns due to potential for boiler explosions if extreme water level deviations are not detected, and non-compliance with safety regulations; all stemming from unreliable pressure readings that can impact critical boiler control systems