Why is....

[n00b 0f l337]

I was just wondering, why must an expansion tank be across a capillary line? Why not something small like 3/16" tube or something.

[GuGaCoSa]

Because it should feed the suction line slowly,and not all the gas at same time

[Xeon th MG Pony]

ya it is to smooth out the action curve, it is like using thermal mass to smooth out temp fluxes, or using a capacitor to dampen out electrical ripple. In this case we are using a cap tube to smooth out gas influx to a shalower curve rather a sudden ingress of gas volume this allows the system to pull a vacuum as it condenses it to liquid which allowes it to draw more out.

In a way the restriction makes the expansion tank transperant to the system as a whole, and allows it to quickly pull a vacuum as it starts to function.

[n00b 0f l337]

Ah didnt think of that . ;)
Thanks for the info.

[Jort]

and to smooth the high pressure too.

We started the cascade for my schoolproject friday.

R22 first stage and R23 second stage.
Started the first stage till -30 and then the second stage kicks in.
At the second stage there is a huge expansion-tank with a volume of about 30-40 liter.
Second stage kicks in with a static pressure of 9bar on both side's. Within 10 sec high pressure gets 22bar.
Closing the suctionport on the compressor lowers it till a point we can screw it back fully open.

Both stage's uses a TXV valve, thats why the high pressure is getting that high. i'll show some pics of this small baby tomorrow :D

expansion valve is connected with an 1/2" tube :p

teacher said next year the other guys need to add a low pressure regulator.