3e151 B Set Vol 2

When inspecting gas-fired heaters, it is important to follow the manufacturers' instructions. These instructions are provided by the manufacturers who have the expertise and knowledge about their specific heaters. They outline the proper procedures and guidelines for inspecting and maintaining the heaters to ensure their safe and efficient operation. Following these instructions is crucial to ensure the safety of the inspector and to avoid any potential damage or malfunction of the heaters.

The most important inspection to perform on a gas-fired furnace is for a gas leak. This is crucial because a gas leak can be extremely dangerous, leading to potential explosions or carbon monoxide poisoning. Detecting and fixing a gas leak ensures the safety of the occupants and prevents any potential hazards.

The inside part of a heat exchanger in a forced-warm air furnace is known as the combustion chamber. This is where the fuel and air mix and ignite to produce heat. The combustion chamber is designed to efficiently burn the fuel and transfer the heat to the surrounding air. It is an essential component of the furnace as it is responsible for generating the heat that is then distributed throughout the building. The burner cone, draft chamber, and casing chamber are not the correct terms for the inside part of a heat exchanger in a forced-warm air furnace.

When inspecting a heat exchanger, the most serious defect to look for is cracks. Cracks in a heat exchanger can lead to leakage of fluids or gases, which can result in reduced efficiency or even complete failure of the system. Cracks can also pose safety hazards, such as the risk of fire or explosion. Therefore, identifying and addressing cracks in a heat exchanger is crucial to ensure its proper functioning and prevent any potential damage or accidents.

Water-gauge glasses are transparent tubes that are attached to a boiler to indicate the water level inside it. The water level in a boiler needs to be monitored to ensure safe and efficient operation. By observing the water-gauge glass, operators can determine if the water level is too low or too high, which can help prevent damage to the boiler and maintain proper steam production. Therefore, the correct answer is that water-gauge glasses are used to indicate the water level of the boiler.

Water hammer is the correct answer. Water hammer refers to the sudden increase in pressure that occurs when a slug of water traveling at high velocity in a steamline comes to a sudden stop. This can cause damage to the system, including pipe ruptures, valve failures, and equipment damage.

When starting up a boiler, it is necessary to close all blowdown valves. Blowdown valves are used to remove impurities and sediment from the boiler, ensuring its efficient operation. By closing these valves during startup, it prevents any unwanted discharge of water or steam from the boiler, allowing it to build up pressure and reach the desired operating conditions. Closing the blowdown valves also helps in maintaining the water level and preventing any loss of valuable water or steam during the startup process.

Wet storage is the other method of boiler layup besides dry storage. Wet storage involves filling the boiler with water and maintaining it at a specific water level to prevent corrosion and maintain the integrity of the boiler during periods of inactivity. This method is commonly used when the boiler will be out of service for an extended period of time. It helps to prevent the formation of rust and scale, ensuring that the boiler remains in good condition and ready for use when needed.

The correct answer is sleeve, thrust, and anti-friction. These are the three common types of bearings used on warm-air furnace assemblies. A sleeve bearing is a type of plain bearing that consists of a cylindrical sleeve that supports the rotating shaft. A thrust bearing is designed to handle axial loads and is used to prevent axial movement of the shaft. Anti-friction bearings, also known as rolling element bearings, reduce friction by using rolling elements such as balls or rollers between the stationary and rotating parts.

Gas burners primary controls operate in response to signals received from thermostats. Thermostats are devices that sense the temperature in the surrounding environment and send signals to the primary controls of the gas burner to adjust the flame accordingly. This allows the gas burner to maintain a desired temperature by turning on or off the gas supply based on the thermostat's signals. Switches and relays may be used in the overall control system, but the primary control and regulation of the gas burner is achieved through the use of thermostats.

A step-modulating space heater control valve has an infinite number of fuel firing rates between high fire and low fire. This means that it can adjust the fuel flow in small increments, allowing for precise control of the heating output. Unlike single-stage or two-stage valves, which have fixed firing rates, a step-modulating valve offers more flexibility and efficiency in regulating the heat output of the space heater. A manual valve, on the other hand, requires manual adjustment and does not provide the same level of control as a step-modulating valve.

The internal feedline is installed at the bottom of the drum. This location allows for efficient transfer of water from the drum to the downcomer tubes, which are located near the side of the drum. Placing the feedline at the bottom ensures that it is submerged in the water, allowing for a continuous flow of water to the downcomer tubes. Additionally, this location helps prevent any interference with the surface blowdown line, which is typically located at the top of the drum.

Cast iron is a suitable material for constructing water columns because it is known for its durability and strength. It can withstand high pressure and is resistant to corrosion, making it ideal for use in water systems. Cast iron also has good heat retention properties, which can be beneficial in regulating the temperature of the water. Additionally, cast iron is relatively inexpensive compared to other materials like stainless steel, making it a cost-effective choice for constructing water columns.

Gags are used to prevent safety valves from lifting during a hydrostatic test. Gags are mechanical devices that are inserted into the valve to hold it in a closed position. They are designed to provide a temporary blockage and prevent the valve from opening under the pressure of the test. This ensures that the valve remains closed and the test can be conducted safely without any leakage or release of pressure.

A pressure relief valve for a water boiler must be spring operated because it needs to automatically release excess pressure when it reaches a certain level. A spring-operated valve is designed to open when the pressure inside the boiler exceeds a predetermined limit, allowing the excess pressure to escape and preventing potential damage or explosion. This type of valve is reliable and does not require external power or control, making it suitable for ensuring the safety of the boiler system.

Ethylene glycol is the most common type of glycol used in hot-water heating systems. It is a colorless and odorless liquid that has excellent heat transfer properties. Ethylene glycol is used as an antifreeze agent in these systems to prevent freezing and to protect against corrosion. It has a high boiling point and low freezing point, making it suitable for use in hot-water heating systems.

If the boiler feed pump is unable to deliver the correct pressure for a hydrostatic test, using a hand pump can be an alternative solution. A hand pump is manually operated and does not rely on the functioning of the boiler feed pump. It can be used to generate the necessary pressure for the test, ensuring that it is conducted accurately and safely.

An upflow warm-air furnace is known as a high-boy furnace because it is designed to be installed in an upright position, with the air intake at the bottom and the warm air discharge at the top. This configuration allows for efficient heating as the warm air rises and circulates throughout the room. The term "high-boy" refers to the furnace's taller and more slender profile compared to other types of warm-air furnaces.

Infrared heaters are not used in areas with ignitable dust, gases, or vapors in hazardous concentrations because of their high surface temperature. This is because the high surface temperature of the heater can potentially ignite or cause explosions when it comes into contact with these hazardous substances. Therefore, it is safer to use other heating methods in such environments to prevent any potential accidents or hazards.

The flame burning in a long, yellow-tipped manner is indicative of insufficient primary combustion. This means that the fuel-air mixture is not being properly ignited, resulting in an incomplete combustion process. This could be caused by factors such as a clogged or dirty burner, inadequate air supply, or improper fuel delivery. Insufficient primary combustion can lead to reduced heating efficiency, increased fuel consumption, and potentially the release of harmful gases.

In an 8-hour shift, you should blow down a steam boiler only once. Blowing down a steam boiler refers to the process of removing sediment and impurities from the boiler water. This is done to maintain the efficiency and safety of the boiler. Blowing down the boiler once during an 8-hour shift ensures that any buildup of sediment or impurities is removed, preventing potential issues with the boiler's performance.

When two or more boilers are connected to a common steam line, having two steam-stop valves is necessary to prevent steam from entering an idle boiler. This is important because if steam were to enter an idle boiler, it could cause damage or lead to inefficiency in the system. By having two valves, one can be closed while the other remains open, ensuring that steam only flows into the active boilers and not into the idle ones.

A steam turbine is used when no electrical power is available. Steam turbines are driven by high-pressure steam generated by boilers, and they convert the thermal energy of the steam into mechanical energy to drive a fan or any other equipment. Since no electrical power is available, a steam turbine is a suitable option as it can operate independently without relying on external power sources.

A high solids concentration in a steaming boiler can cause a priming and foaming condition. When there is a high concentration of solids, such as dissolved minerals or impurities, in the boiler water, it can lead to the formation of foam or froth. This foam can interfere with the normal operation of the boiler, causing priming, which is the carryover of water droplets along with the steam. This can result in reduced efficiency, increased corrosion, and potential damage to the boiler and other equipment. Therefore, it is essential to maintain proper water treatment and control the solids concentration in the boiler to prevent this issue.

A continuous blowdown system is designed to maintain the concentration of the boiler water within the appropriate limits. One of its main functions is to remove foreign solids from the boiler water. These foreign solids can include impurities, such as dirt, rust, and other contaminants that may accumulate in the boiler system. By removing these foreign solids, the blowdown system helps to prevent potential blockages, corrosion, and other issues that can arise from the presence of these impurities in the boiler water.

Wire brushes are used to remove soot, dirt, and scale from flues and fireboxes of boilers because they have stiff bristles that can effectively scrub away the buildup. Chemicals may be used in conjunction with wire brushes, but they are not the primary tool for removing these substances. Putty knives are not suitable for this task as they may damage the surfaces of the flues and fireboxes. Soap and water alone are not sufficient for removing stubborn soot, dirt, and scale.

The correct answer is "stays." In a boiler, the flat surfaces are held in place by braces called stays. Stays are structural components that provide support and prevent movement or deformation of the flat surfaces. They help maintain the integrity and stability of the boiler structure, ensuring that the flat surfaces remain securely in place during operation.

A smoke detection system sensor is a cadmium sulfide photocell. This type of sensor is commonly used in smoke detectors to detect the presence of smoke particles in the air. When smoke enters the detector, it scatters light onto the photocell, causing a decrease in the photocell's resistance. This change in resistance is then detected by the smoke detection system, triggering an alarm to alert occupants of a potential fire.

The correct answer is mechanical and chemical. Mechanical cleaning involves physically removing deposits and debris from the waterside of boiler tubes using tools such as brushes, scrapers, or water jets. Chemical cleaning, on the other hand, involves using chemicals or cleaning agents to dissolve or loosen deposits and then flushing them out. Both methods are commonly used in combination to effectively clean the waterside of boiler tubes.

When scale deposits in a boiler interfere with heat transfer, it means that the heat produced by the boiler is not efficiently transferred to the water. This can lead to decreased efficiency and increased energy consumption. Additionally, when scale deposits impede water flow, it can result in reduced water circulation within the boiler, leading to uneven heating and potential overheating in certain areas. Therefore, excessive scale deposits can have a negative impact on the overall performance and functionality of the boiler.

After seasonal overhaul is completed, hot-water system layup is usually done. This means that the hot-water system is shut down and prepared for a period of inactivity, typically during the off-season or when it is not needed. Seasonal overhaul refers to the maintenance and inspection activities carried out on the system before it is put back into operation. By performing the layup after the seasonal overhaul, any necessary repairs or adjustments can be made, ensuring that the system is in optimal condition before it is shut down.

The limit control unit is responsible for stopping the burner in a gas-fired furnace when the temperature becomes excessive. This unit acts as a safety mechanism to prevent overheating and potential damage to the furnace or surrounding areas. It monitors the temperature and when it reaches a predetermined limit, it sends a signal to shut off the burner, ensuring that the temperature remains within a safe range.

Gas space heaters can be of different types based on the way they circulate air and whether they are vented or unvented. The options provided in the question, such as ceiling, floor, and wall, refer to the physical location of the heaters. However, the correct answer, "room," refers to the type of gas space heaters that can be both gravity or mechanical air-circulation type and vented or unvented. In other words, gas space heaters designed for rooms can have different air-circulation mechanisms and venting options.

An unvented space heater must be used only in well-ventilated rooms because it does not have an exhaust or vent to remove the combustion byproducts, such as carbon monoxide, outside. Without proper ventilation, these byproducts can accumulate in the room and pose a serious health risk to the occupants. Therefore, it is important to use an unvented space heater only in a well-ventilated area to ensure the safety and well-being of everyone in the room.

A compressed spring keeps a safety valve closed against the force developed by the steam pressure acting under the valve disc. When the steam pressure exceeds a certain level, the force exerted by the compressed spring is overcome, causing the safety valve to open and release the excess pressure. The compressed spring acts as a mechanical mechanism to maintain the valve in a closed position until the pressure reaches a critical point.

A balanced mechanical draft system is the most flexible because it combines the features of both induced and forced draft systems. It uses a combination of fans to create a balanced air pressure within the system, allowing for more control over the airflow. This flexibility is important in various industrial applications where the airflow needs to be adjusted based on different operating conditions.

A compound Bourdon gauge is a type of pressure gauge that is capable of measuring both pressure and vacuum. This is achieved by using two separate Bourdon tubes, one for measuring pressure and the other for measuring vacuum. The pressure tube is designed to expand under pressure, while the vacuum tube is designed to contract under vacuum. By combining the readings from both tubes, the gauge can accurately measure both positive and negative pressure values, making it suitable for applications where pressure and vacuum measurements are required.

If a complete failure of ignition occurs, the purge setting should be set for 5 minutes. This means that the system will purge the fuel-air mixture for 5 minutes before attempting to ignite it again. This is done to ensure that any accumulated fuel or gas is cleared from the system before another ignition attempt is made. A shorter purge setting may not be enough time to fully clear the system, while a longer purge setting may unnecessarily delay the ignition process. Therefore, a 5-minute purge setting strikes a balance between ensuring safety and efficiency.

Float-type cutoffs are used to accomplish low-water protection. These devices are designed to detect the water level in a system and automatically shut off the flow of water if it falls below a certain level. They work by utilizing a float mechanism that rises and falls with the water level. When the water level drops too low, the float triggers a switch that shuts off the water supply, preventing damage to the system. This mechanism is commonly used in boilers and other water-based systems to ensure that the water level remains at a safe and functional level.

The tubes of a water-tube boiler are surrounded by hot gases. In a water-tube boiler, the water flows through the tubes while the hot gases produced by burning fuel surround the tubes. This design allows for efficient heat transfer from the hot gases to the water, resulting in the generation of steam. Hot air, water, and steam are not the correct answers as they do not directly surround the tubes in a water-tube boiler.

When pressure is increased, the boiling point of water also increases. This is because an increase in pressure compresses the water molecules, making it harder for them to escape into the gas phase. As a result, more heat is required to break the intermolecular forces and convert water into vapor. Therefore, an increase in pressure raises the boiling point of water.

Boilers with 500 square feet or more of water heating surface must have at least two means of feeding water. This is necessary to ensure a reliable and continuous water supply to the boiler for efficient operation and to prevent any potential damage or failure. Having multiple means of feeding water also provides redundancy in case one system fails or requires maintenance, allowing the boiler to continue functioning without interruption.

The correct answer is float and probe. Float and probe are the two types of low-water cutoffs used on steam boilers. A float type low-water cutoff operates by using a float to detect the water level in the boiler and shut off the burner if the water level drops too low. A probe type low-water cutoff uses a probe to directly sense the water level in the boiler and shut off the burner if the water level falls below a certain point. These cutoffs are important safety devices to prevent damage to the boiler and ensure proper operation.

The adjustment that provides a choice of firing rate at burner startup is UNISON/SEQUENCE. This adjustment allows the user to select between the two options, allowing for flexibility in controlling the firing rate during startup.

Closing and tagging all valves and drains of a boiler before entering it for an inspection is done to prevent steam and water from entering the unit. This is important because entering a boiler while it is still pressurized or contains water can be extremely dangerous. By closing and tagging all valves and drains, it ensures that no steam or water can enter the unit while the inspection is being conducted, thereby ensuring the safety of the person entering the boiler.

A pressure-regulating valve is the device that automatically supplies water to a hot-water boiler. This valve is responsible for maintaining a consistent and safe pressure level within the boiler by regulating the flow of water. It ensures that the boiler is supplied with the appropriate amount of water to maintain optimal functioning and prevent any damage or accidents that may occur due to excessive pressure.

When floors or other objects reradiate heat to the air, the method of heat transfer being used is convection. Convection is the process by which heat is transferred through the movement of fluids, such as air or water. In this case, the heat from the floors or objects is transferred to the surrounding air through convection, as the air near the objects gets heated and rises, creating a convection current that spreads the heat throughout the room.

Water hammer in a piping system is a phenomenon that occurs when there is a sudden change in the flow velocity of water, resulting in pressure surges and vibrations. Flash tanks are used to prevent water hammer by providing a space for the sudden increase in pressure to be absorbed. When there is a surge in pressure, the flash tank allows the excess water and steam to be released, preventing the pressure from damaging the piping system. Open traps, saturated pressure, and pressure release valves do not specifically address the issue of water hammer prevention.

A steam-stop valve must be of the outside screw-and-yoke, rising-stem type whenever it is 2 inches or larger. This means that for steam-stop valves that are 2 inches or larger in size, they should have an outside screw-and-yoke mechanism with a rising stem. This type of valve design allows for better control and regulation of steam flow in larger systems.

The boiler low-water cutoff unit is responsible for protecting the equipment from damage caused by low water levels. It does this by stopping the operation of the burner, activating the feedwater system, and activating a low-water bell to alert the operator. However, it does not bypass the feedwater heater. By not bypassing the feedwater heater, the unit ensures that the water is properly heated before entering the boiler, which helps maintain the efficiency and performance of the equipment.