Final answer:
Long hoses between the unit and the recovery machine lead to excessive pressure drop, increased recovery time, and increased emissions, hence the correct answer is D) all of the above.
Step-by-step explanation:
The question relates to the effects of using long hoses between the unit and the recovery machine. When long hoses are utilized, they indeed create several negative effects due to the physical principles of fluid dynamics. One such effect is A) excessive pressure drop, which occurs as the refrigerant travels over a longer distance, losing energy due to friction and other resistive forces. As a result, the pressure at the end of the hose is significantly lower than at the beginning.
Another impact is B) increased recovery time. The longer the hose, the more volume it has, and the longer it will take to move the same amount of refrigerant compared to a shorter hose. Time is lost filling the hose volume, and the recovery machine has to work harder to move refrigerant through the increased length.
The third implication is C) increased emissions. Any leaks or permeation in the hose are magnified due to the greater surface area of a long hose, resulting in a higher potential for refrigerant to escape into the atmosphere, thus raising environmental and safety concerns.
Therefore, the correct answer to the question is D) all of the above; long hoses between the unit and the recovery machine should not be used because they cause excessive pressure drop, increased recovery time, and increased emissions.