situation: 1. i have 2 pipes. the source is pipe A and i will connect it to pipe B. the diameter of Pipe varies and has a range, lets say around 1 in. pipe A can be larger than pipe B. what mechanism shall i i use in order to avoid leakage during the process? the fluid is a refrigirant and pressurized like in most air conditioners (window-type) 2. i have this evaporator and i want to test its capacity. do i need to have the complete aircon parts (condenser, compressor, expansion device, etc) or just a refrigirant tank, pump and an air source.? 3. if the test is done, what design shall i use to be sure that there is no refrigirant left in the evaporator and it goes back to the tank?