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Questions in engineering

[Answered] Choose all options that apply. Which of the following uses of soldering are approved in the HVAC industry? a) Joining refrigerant lines b) Joining copper pipes used for water c) Joining combustible gas lines d) Joining electrical wiring

[Answered] What happens when you slide the rear trailer axle to the rear? A. Weight is shifted from the rear axle to the drive axle B. Weight is shifted from the drive axle to the rear axle C. Weight is shifted from the steer axle to the drive axle

[Answered] What must a technician do before connecting gauges to charge liquid refrigerant? a) Subtract the tare weight from the cylinder weight. b) Add the refrigerant. c) Find the tare weight of an empty cylinder. d) Weigh the cylinder. e) Close the service valve.

[Answered] Where can you add the vapor refrigerant in non-operating systems? A. The charging device B. The low-pressure side C. The refrigerant cylinder D. The high-pressure side

[Answered] (c) A separately excited d.c motor with a reactive feedback diode across it is fed from a [tex]$240 V, 50 Hz$[/tex] a.c supply through a single phase half-controlled bridge rectifier. The armature inductance and resistance are 0.06 H and [tex]$6 \Omega$[/tex] respectively. If the firing delay angle is [tex]$80^{\circ}$[/tex] and motor back e.m.f is 150 V , determine the mean input voltage of the d.c motor.

[Answered] An HVACR service technician has been called in to inspect a system with a line leak. She sees that the refrigerant line has been in direct contact with a concrete block wall. How might this have contributed to a leak? Vibration Lack of stability Corrosion Pressure on the joints

[Answered] The issue of overheating due to excessive compression ratios is prevalent in what type of refrigeration system? A. Remote piped systems B. Low-temperature systems C. High-temperature systems D. Medium-temperature systems

[Answered] A mat foundation has dimensions of 40 m x 20 m. The live load and dead load on the mat are 250 MN. The mat is placed over a layer of soft clay that has a unit weight of 19 kN/m³. Find Dr for a fully compensated foundation.

[Answered] Match the parts of an electronically controlled expansion valve to their functions. 1. Remotely controlled valve 2. Thermistor 3. Transformer * Placed in the refrigerant stream near the evaporator outlet to respond quickly to temperature changes * Transmits a voltage change to an electronic controller * Adjusts opening in metering devices

[Answered] What does mutual inductance depend on? A. Resistance between the coils B. Coupling coefficient and inductances C. Voltage across the coils D. Capacitance of the system