(auto)cascades and safety

[Unknown_road]

First off all I don't like it that lots of people here build cascades without high pressure cut off's. Now I see autocascades becoming more popular and I'm afraid people won't use high pressure cut offs on them as well while the need for it on an autocascade is larger by far.

Suppose you get an autocascade working well, what will happen when you put a load on the evap bigger then what you tuned it for? The HX also gets more load and might not be able to handle this. What will happen is the temperature will go up and the high pressure gas isn't able to condens anymore and pressures will rise very very quickly. This is a very dangerous but likely scenario. When an autocascade doesn't work fully this change is even greater.

The same will happen when the low pressure gas expansion device (cappilair, TXV etc) gets clogged with debris or will freeze shut because of water remains in the system or when more stages are used oil that gets trough the oil sep. Also very possible to happen.

Offcourse these things can also happen with cascades but since the autocascades we build are less reliable in their workings, the chance of failure is higher so I wanted to point this out once more.

take this serious and always use at least high pressure cut off valves!!!!!

[n00b 0f l337]

Runmc has started stocking them at UTI for a reason people! Safety first!
This is very very true, also, expansion tanks are always a good idea.
AND NEVER CHARGE A CASCADE WITH THE SETUP ON!

[jinu117]

Stealing this for the safety thread

[runmc]

thank you Unknown_road for this information

You have always been a big contributor to the phase community and we appreciate you..

[Trouffman]

Thanks Unknown_road

Some of user don't know all the safety rules Thanks for your thread !

[Unknown_road]

thanks ron!


I think most people here think they only need a high pressure cut off in case something radical happens like compressor failure or something but there is a lot more that could go wrong!!!

[jinu117]

thanks ron!


I think most people here think they only need a high pressure cut off in case something radical happens like compressor failure or something but there is a lot more that could go wrong!!!

Nod. Now, some parts do have fusable plugs over 450psi or 400psi... some receivers do, some oil seps do, etc. Another reason it is sometimes cheaper to go comercial one than homemade in long run

[Xeon th MG Pony]

And while talking about electrical interlocks I will chime in by saying all ways pay strict attention to your wiring and all ways ensure a proper use of fuses or breakers on the system its self IE: A breaker on each compressor no higher then its LRA rating or fuses matched to the LRA(The slow blow kind as this will stop them from blowing on start up, breakers have this function in built).

All ways ensure the circuit you will be running your Cascade and bench rig is able to handle the power draw with at least (I mean absolute least) 10% over head, ideal is at least 20% (By over head I mean you should never load a circuit to a 100% you should all ways have 20% of its capacity un-used as a safety margin)

Power line size should all ways be properly matched to its consumption, or larger diameter, I personally all ways use the next gauge up from what it is expected to use to ensure I have a safety margin and this way it can pipe the start up surge no problem and has very low voltage drop. Under sized wire is a danger! It will heat up as the unit is running

(If you have been vacuuming your place for a bit feel the cord on the vacuum, you'll notice its warm they went with the minimum gauge they could to save money on manufacturing yet still be within safety margins. This is hard on the motor when starting as there is a large voltage drop (but since the motor at start up is mostly unloaded it isn't as bad for the vacuum as it will be for some thing that is moderately loaded on start up, it will have to struggle to start at the reduced voltage and lower current due to line loss) ).

With this example we can carry over to the cascade as it will suffer the exact same effect at start up of being starved of current with improperly sized wire. The best way to do it is find its running current add 20% to that then see what gauge of wire you'll need, then select the next size up on the list, this will give it tons of start up room and guarantee it will handle the current load with no issue with a safety margin

You should all so buy or make an insulated box for your circuit connections and to house the fuses and or breakers.

You all ways should take your time to understand the basics of AC wiring whether it is for a single stage or a behemoth of a Cascade as it will greatly influence the performance and life of the system. A current starved system doesn't live a longe life Nor does on that burns down the house due to a small electrical failure!

So all ways make good and proper use of fuses and breakers along with blow out valves and High pressure cut offs they all work to gether to keep the system running and you alive.

[Weee]

Stealing this for the safety thread

Ha, yes, tried to lead you to do that already! good information