filling multiple tanks (air) with minimal compressor stress

[dsp]

Hi all!
I have a paramina typhoon compressor with 3 filling hoses.
The way that i have been filling until now was to let the tanks fill up to the compressor limit,
then the compressor stops, the tanks cool, the compressor then tops them up a bit etc etc.
The other day my instructor informed me that this is a really bad practice for the compressor and that it's vastly better to keep it running when it starts filling and not start/stop it.
so the question is, how to do it ?
my current procedure is:
1) connect all the tanks, open them
2) slowly open the tank valves until they all equalize very very slowly and gently (no more than 18bar/min)
3) start the compressor/reaches limit turns off/starts again/turns off
4) close tanks, change tanks, repeat.
how can i properly change tanks while it's running in order to keep it running and not stress any tanks?
thanks so much!

 

[rx7diver]

dsp,

My intuition suggests that the more expensive air (to your compressor) is the higher pressure air. So, equalizing your three tanks right at the beginning (as you describe) is probably not the better solution.

Maybe a better approach is to note the current pressure of all of the tanks you need to fill. Then attach the three tanks having the lowest pressure to the three fill whips. Then start the compressor with the whip to the tank with the lowest pressure turned on (but the other two whips turned off).

As the pressure of the first tank reaches the pressure of the tank having the second lowest pressure (which is attached to one of the closed whips), then open the whip to that second tank. Now you're filling two tanks simultaneously which have the same pressure, though this pressure is less than the pressure of the third lowest pressure tank (which is attached to your third whip, which is still turned off).

See the pattern?

At some point you will be filling these three tanks simultaneously.

Now you're operating your compressor as if you are filling a cascade system.

Safe Diving,

rx7diver

 

[guruboy]

Does the air come straight from the compressor or do you have a bank?

If no bank, maybe you could fill three up to almost full. Then take one or two off and replace with new tanks. Turn on the new tanks and quickly turn off the last almost filled tank so that it doesn't lose too much air to equalization.

Once they are cooled, top them off by staggering them so that the compressor keeps running.


However, if what you are currently doing is -
1) fill tanks (start)
2) wait for tanks to cool (stop)
3) top off (start)

I wouldn't worry about stress to the compressor. It's frequent start/stop in a short time that would really be an issue. (same reason why you dont want to let your AC keep turning on/off during intermittent blackouts).

 

[dsp]

dsp,

My intuition suggests that the more expensive air (to your compressor) is the higher pressure air. So, equalizing your three tanks right at the beginning (as you describe) is probably not the better solution.

Maybe a better approach is to note the current pressure of all of the tanks you need to fill. Then attach the three tanks having the lowest pressure to the three fill whips. Then start the compressor with the whip to the tank with the lowest pressure turned on (but the other two whips turned off).

As the pressure of the first tank reaches the pressure of the tank having the second lowest pressure (which is attached to one of the closed whips), then open the whip to that second tank. Now you're filling two tanks simultaneously which have the same pressure, though this pressure is less than the pressure of the third lowest pressure tank (which is attached to your third whip, which is still turned off).

See the pattern?

At some point you will be filling these three tanks simultaneously.

Now you're operating your compressor as if you are filling a cascade system.

Safe Diving,

rx7diver

rx7diver thanks for replying. What you suggest is a really good idea for saving time from having to wait until they all equalize to start the compressor. i think i'll start doing it since this is the most time consuming aspect of starting the fill and indeed it makes sense. all it takes is 3 measurements.

Does the air come straight from the compressor or do you have a bank?

If no bank, maybe you could fill three up to almost full. Then take one or two off and replace with new tanks. Turn on the new tanks and quickly turn off the last almost filled tank so that it doesn't lose too much air to equalization.

Once they are cooled, top them off by staggering them so that the compressor keeps running.


However, if what you are currently doing is -
1) fill tanks (start)
2) wait for tanks to cool (stop)
3) top off (start)

I wouldn't worry about stress to the compressor. It's frequent start/stop in a short time that would really be an issue. (same reason why you dont want to let your AC keep turning on/off during intermittent blackouts).

guruboy again thanks! i don't have a bank. your idea indeed solves the problem completely. it will be a bit of a juggle but it's the only solution that would keep the compressor running.
what i'm currently doing is what you described so maybe it's not so bad. in a few days i hope to have a chat with the paramina rep so if anything interesting arises i'll post it here.

thanks guys!