Mechanical Quiz Set A

The correct answer is 2 Safety Valve. Boilers with a generating capacity exceeding 907 kg/hr require multiple safety valves to ensure proper pressure relief and prevent overpressure situations. These safety valves are crucial in maintaining the safety and integrity of the boiler system by releasing excess pressure and preventing potential explosions or damage. Having multiple safety valves also provides redundancy, ensuring that there is always a backup valve available in case one fails or requires maintenance.

The correct answer is "Governor." A governor is a safety device in a passenger elevator that activates if the car travels faster than its rated speed. It works by grasping the guide rail to stop the car safely. The governor is designed to prevent the elevator from exceeding its maximum speed and ensure the safety of passengers.

According to the NBC (National Building Code), the clearance between the underside of the car and the bottom of the pit should not be less than 600 mm. This means that there should be a minimum distance of 600 mm between the car and the bottom of the pit to ensure safety and proper functioning of the car.

The maximum width of the steps is 330 mm. This means that the steps cannot be wider than 330 mm.

The term "Ton of Refrigeration" is used to measure the cooling capacity of a refrigeration system. It refers to the amount of heat that needs to be removed in order to freeze or melt one ton (2,000 pounds) of ice in 24 hours. In this case, the cooling effect obtained when 1 ton of ice melts to water at the same temperature in 24 hours is equivalent to 12,000 Btu/hr, which is the definition of one ton of refrigeration.

The given options provide different values for the minimum diameter of hoisting and counterweight rope under NBC. However, the correct answer is 30 mm, which implies that according to NBC regulations, the minimum diameter of the hoisting and counterweight rope should be 30 mm.

The spacing provided for the elevator with a single bank in a non-residential building should be 1.5 times more than the elevator car depth. This extra spacing is necessary to ensure that there is enough room for the elevator car to move in and out of the elevator shaft smoothly, without any obstructions or potential safety hazards.

The correct answer is Truss. A truss is a framework made of welded steel that supports the moving stairway component. It is a three-section built-up structure that provides stability and strength to the staircase.

R-22 is the recommended refrigerant for residential, commercial, and industrial applications using split type air conditioning systems. R-22, also known as chlorodifluoromethane, is commonly used in older air conditioning units. It has good cooling properties and is effective in cooling large spaces. However, R-22 is being phased out due to its harmful effects on the ozone layer. As a result, newer air conditioning systems are being designed to use alternative refrigerants such as R-410A, which is more environmentally friendly.

An air motor is an air-operated device that is commonly used to open or close dampers or valves. It utilizes compressed air to generate rotational motion, which can be used to control the position of the damper or valve. This makes it a suitable choice for applications where precise control and quick response are required. The air motor's ability to operate in various environmental conditions and its compact design also make it a popular choice in industrial settings.

The correct answer is Disconnect Switch. In escalators, the disconnect switch is located at the bottom truss and is used to stop or prevent the escalator from starting during maintenance service. It has on and off positions, allowing for easy control and isolation of power to the escalator. This ensures the safety of maintenance workers and prevents any accidental operation of the escalator while maintenance is being carried out.

The handrail guard switch is the correct answer because it is specifically designed to stop the escalator if a foreign object becomes wedged at the guard. This switch serves as a safety mechanism to prevent accidents or injuries caused by objects getting stuck in the handrail guard. By activating this switch, the escalator can be immediately stopped, ensuring the safety of the passengers and preventing any further damage to the escalator.

The minimum face to face distance between elevators in three and four car grouping is 2.0 meters. This distance is necessary to ensure safe and efficient movement of people and equipment between the elevators. It allows for enough space for individuals to comfortably pass each other and for any necessary maintenance or repair work to be carried out. A smaller distance could potentially lead to congestion and hinder the overall functioning of the elevator system.

A truss is a structural framework that is used to support and distribute loads. In the context of installing an escalator, a truss configuration with multiple sections is necessary to provide sufficient strength and stability. The use of a 3 section truss allows for the distribution of the load evenly and ensures that the escalator is securely supported. This configuration is likely the most suitable choice for the installation of an escalator.

An alternator is a device that converts electrical energy into mechanical energy, by electromagnetic means. It does this by using a rotating magnetic field to induce an alternating current in the stator windings. This alternating current can then be used to power electrical loads or charge a battery. Unlike a generator, which typically uses brushes and slip rings to transfer the electrical energy, an alternator uses a rectifier to convert the alternating current into direct current. Therefore, an alternator is the correct answer in this case.

A hydraulic elevator consists of several components that work together to facilitate its operation. The safety shoe is an essential component that prevents the elevator from falling in case of a hydraulic failure. The weighing device ensures that the elevator does not exceed its maximum weight capacity. The sheave is responsible for guiding and supporting the elevator cables. However, the counterweight is not a component of a hydraulic elevator. Counterweights are typically used in traction elevators to balance the weight of the elevator car and reduce the amount of energy required for operation.

A corporation stop is a type of stop valve that is placed in the service pipe close to the connection at the water main. It is used to control the flow of water and is typically installed by the water utility company. The corporation stop allows for easy access and maintenance of the water supply, as it can be shut off quickly if needed.

The door lock switch is the correct answer because it is responsible for preventing the door from opening while the elevator car is in motion. It ensures that the door will only open when the car has stopped at a floor. The other options, such as the fascia plate, magnetic break, and outside door latch, do not have this specific function of controlling the door's opening during elevator car run.

The correct answer is "Down Collective Control." This means that the car's system is set to answer incoming calls in a descending order, starting from the highest priority and moving down. This implies that if multiple calls come in at the same time, the system will prioritize the call with the highest importance and answer it first, followed by the next important call, and so on.

A humidistat is a device used to measure and control humidity levels in the air. It is often used in conjunction with a dehumidifier or humidifier to maintain a desired level of humidity. The term "hygrostat" is another name for a humidistat, as both words refer to the same device. Therefore, the correct answer is "Hygrostat."

An air conditioner is an apparatus that can heat, cool, clean, and circulate air. It is a device used to regulate the temperature, humidity, and air quality in a specific space. It works by extracting heat from the indoor air and transferring it outside, thereby cooling the room. Additionally, it can also provide heating during colder months by reversing the cooling process. The air conditioner also filters and cleans the air, removing dust, allergens, and pollutants. Overall, an air conditioner is a versatile appliance that can provide comfort and improve indoor air quality.

A bumper is a device designed to stop an elevator car or counterweight from descending beyond its normal limit of travel. It acts as a cushioning mechanism that absorbs the impact and prevents any further downward movement. When the elevator reaches its maximum allowed travel distance, the bumper comes into contact with a stopping mechanism, which helps to ensure the safety of the elevator and its passengers.

The correct answer is 5 meters. This means that the distance of the smokestacks above the building within a 50-meter radius is 5 meters. This implies that the smokestacks are elevated 5 meters above the building.

The minimum height required for refrigerant piping above the floor when crossing a passageway in any building is 2.30 meters. This height ensures that there is enough clearance for people to walk underneath the piping without any risk of collision or obstruction. It also allows for proper maintenance and accessibility to the piping system.

Hydronics is the correct answer because it refers to the art and practice of heating and cooling with water. This term specifically relates to the use of water as a medium for transferring heat in heating, ventilation, and air conditioning (HVAC) systems. It involves the circulation of water through pipes, radiators, and other components to regulate temperature. Hydraulics, hyphonics, and hygrostat are unrelated terms and do not involve the use of water for heating and cooling purposes.

The current overload safety switch is designed to stop the escalator automatically if an abnormal current is supplied to the motor. This switch acts as a protective measure to prevent damage to the motor and ensure the safety of the escalator system. When the current exceeds a certain threshold, the switch detects this abnormality and immediately cuts off the power supply to the motor, stopping the escalator. This helps to prevent overheating, electrical malfunctions, and potential accidents caused by excessive current flow.

The minimum height requirement for a window type AC installed on ground floors is 2.13 meters. This height is necessary to ensure proper ventilation and to prevent any obstruction to the airflow. Installing the AC unit at this height allows for efficient cooling and avoids any potential damage or interference with the unit's functionality.

The correct answer is "Up Collective Control". This answer is based on the information given in the question, which states that the system answers calls starting from the lowest and continues in ascending order. Therefore, the "Up Collective Control" option best fits this description.

Dampers are valves or plates that control the flow of air inside ducts, chimneys, air handlers, or other air handling equipment. They can either stop or regulate the airflow, allowing for better control of ventilation and temperature. Dampers are commonly used in HVAC systems to adjust the amount of air entering or leaving a space, ensuring optimal air circulation and comfort.

Air-conditioning refers to the process of controlling and regulating the temperature, humidity, and air quality of a confined space to create a comfortable environment. It involves the use of various equipment such as air conditioners and air handling units to achieve a temperature lower than that of the immediate surroundings. Therefore, the achievement of a temperature below that of the immediate surroundings is a characteristic of air-conditioning.

The correct answer is 1 meter. This means that no part of the boiler should be closer than 1 meter to the wall. This distance is important to ensure proper ventilation and prevent any potential fire hazards. Keeping the boiler at a safe distance from the wall allows for better airflow and reduces the risk of overheating.

The minimum distance required if the building is not made of fire resistive materials is 3.00 mts. from the outside wall. This means that any structure or object must be at least 3.00 meters away from the outer wall of the building to minimize the risk of fire spreading. This distance allows for better fire prevention and safety measures to be implemented.

The minimum angle of inclination for an escalator is typically 30 degrees. This angle ensures a safe and comfortable incline for passengers while allowing for efficient vertical transportation. Escalators with steeper inclines can be more difficult to navigate, especially for individuals with mobility challenges.

The correct answer is 50 GALS. This suggests that on average, each person consumes 50 gallons of water. This could be interpreted as the average amount of water used by individuals for various purposes such as drinking, cooking, bathing, and other household activities.

The correct answer is 558 mm. Under NBC (National Building Code), the minimum width between balusters in an escalator is 558 mm. This measurement ensures that there is enough space for individuals to pass through safely without any obstruction or risk of injury. It is important to adhere to these regulations to maintain the safety standards of escalators in public spaces.

Ammonia is commonly used as a gas refrigerant with water due to its favorable thermodynamic properties. It has a low boiling point and high heat transfer coefficient, making it efficient in absorbing heat from the surroundings. Ammonia is also non-toxic, non-flammable, and has low global warming potential, making it a safer and more environmentally friendly option compared to other refrigerants like Freon.

A rectifier is a device that converts alternating current (AC) to direct current (DC). It does this by allowing current to flow in only one direction, effectively "rectifying" the current. This is typically achieved using diodes, which act as one-way valves for electric current. By converting AC to DC, a rectifier enables the use of DC-powered devices or the charging of DC batteries. In contrast, compressors, alternators, and generators are devices that are involved in the production or conversion of AC power, rather than the conversion of AC to DC.

A governor is a device that consists of a flyball or flyweight mechanism designed to stop an elevator. It is responsible for controlling the speed of the elevator and preventing it from exceeding a safe limit. When the elevator moves too fast, the flyballs or flyweights in the governor mechanism extend outwards, activating a braking system that brings the elevator to a stop. This ensures the safety of passengers by preventing the elevator from accelerating uncontrollably or free-falling.

A knife switch is a type of switch that is manually operated and is used to interrupt the flow of electric current. It is often used in situations where the current supply needs to be completely cut off, such as during inspection, maintenance, or repairs. By flipping the knife switch, all current supply to the escalator can be disconnected, allowing for safe and efficient work to be carried out.

The provision of a safety valve is necessary in every boiler to prevent excessive pressure build-up. A safety valve is designed to release steam or other gases when the pressure inside the boiler exceeds a certain limit. This helps to protect the boiler and its surrounding equipment from potential damage caused by overpressure. By having a safety valve, the boiler operator can ensure the safe operation of the boiler system and prevent any potential accidents or explosions.

When two or more boilers are connected in parallel, it is important to have a "No Return or Shut Off Valve" in the system. This valve is designed to prevent the backflow of water from one boiler to another. It ensures that each boiler operates independently and prevents any potential damage or malfunction caused by the mixing of water from different boilers. Additionally, this valve allows for easy isolation and shut off of individual boilers for maintenance or repairs without affecting the operation of the other boilers in the system.

The correct answer is 135-197 F because this range falls within the specified temperature range for the heat detector. The heat detector is designed to activate when the temperature reaches a certain threshold, and this range encompasses that threshold.

The correct answer is main drive chain, step chain, handrail, drive chain, bottom sprocket. This is because an escalator consists of several important components that work together to transport people between different levels of a building. The main drive chain is responsible for powering the escalator, while the step chain moves the individual steps. The handrail provides support and safety for passengers. The drive chain is another component involved in the movement of the escalator. Finally, the bottom sprocket helps to guide and control the movement of the chains and steps.

The seasonal energy efficiency ratio (SEER) is a measure of the cooling efficiency of an air conditioner over an entire cooling season. It is calculated by dividing the total cooling output of the air conditioner in BTU/hr by the energy input in watt-hours during the same period. SEER is a useful metric for comparing the energy efficiency of different air conditioners and determining their overall performance in terms of cooling output relative to energy consumption.

In order to ensure safety and prevent accidents, it is necessary to install certain safety features in the pit of elevators. One such requirement is that if the pit extends more than 660 mm below the sill of the pit access door, certain installations should be made. This ensures that there is adequate protection and safety measures in place to prevent any mishaps or injuries that may occur in the pit area.

A fan coil unit is a mechanical equipment that is part of a central air conditioning system. It is used to dehumidify and cool the airstream that is injected into the conditioned space. This unit contains a fan, a heating or cooling coil, and a filter. The fan helps to circulate the air, while the coil removes moisture and heat from the air, making it cooler and less humid. This process helps to create a comfortable indoor environment.

A pressure relief valve is a safety device that is designed to protect a system from excessive pressure. In this case, the insufficient water flow on the heater during a brown out can cause a buildup of pressure. The pressure relief valve is responsible for releasing this excess pressure, preventing any potential damage or hazards.

The correct answer is "Stop Valves". Stop valves are necessary for the installation of a refrigerant system containing more than 9 kgs. These valves are used to control the flow of the refrigerant and allow for maintenance and repairs to be carried out on the system. They are an essential component of the system and ensure its safe and efficient operation.

Air-conditioning is the correct answer because it is a device that maintains control of the indoor environment by regulating the temperature, humidity, air circulation, and air purity. It is commonly used in homes, offices, and other buildings to provide a comfortable and healthy indoor environment for the occupants. Air-conditioning systems can also be used for industrial purposes to control the temperature and humidity levels for materials that are handled or stored in a specific space.

The device that opens and closes the electric current in an elevator when it has reached the designated end of the travel course is called an emergency switch. This switch is specifically designed to cut off the power supply to the elevator in case of an emergency or when the elevator has reached its intended destination. It ensures the safety of the passengers by preventing any further movement of the elevator and shutting down the electrical system.