Financial planning, compressor

[formernuke]

Air intake is a given. I did consider building an enclosed shed outside that room. Major complication, I live in New England so winter temps are an issue.

Hence basement I have the space there without lugging heavy tanks up and down steep stairs.

 

[Cio]

You should let the idea of having a 4.5K in this setup go. It would serve no functional purpose whatsoever and just cost you money.

You are on the right track using a reg to fill, it reduces the amount of attention the process requires by quite a bit.

If you have big room in your basement, go for it, but heat will be an issue and these do throw some heat so keep that in mind.

You can start it with the block temp as low as 32. If you have a garage and can wheel it outside, the cold will do it well and you get more capacity out of it in the cold. The units for outdoor use have insanely small block heaters you could add one for $18 and put it in a shed.

https://www.homedepot.com/p/Frost-King-3-ft-Electric-Heat-Cable-HC3A/202526143

 

[rjack321]

How many tanks are you trying to refill at one time? And how much time do you want to sit there are fill them?

Are you planning on filling nitrox?

Are you actually diving in winter and needing fills then? Or potentially leaving it for a few of the coldest months?

Any neighbors to be concerned about (ie a duplex)? Compressors are noisy noisy

 

[formernuke]

I'm filling 2 tanks, maybe 3. I dive year around.

 

[RayfromTX]

I would not want my compressor in a completely different place than the tanks I'm filling. Both require my oversight. With my setup which is a rix continuous blending nitrox into a bank of 4 big bottles and filling tanks from there or filling both at the same time, I need to be watching the fills, the compressor and the O2 content while also draining condensate and being close to the shutoff switch and yanno, maybe a fire extinguisher.

I'm not seeing how to make this work on multiple levels of your house but I also would never try to talk you out of having your own setup. I don't trust people at dive shops to fill my tanks, I'm a long way from a dive shop and I am particular about how things get done so owning my own was just going to happen. It helps if you are handy at fixing things but study up on this because being a good mechanic and being talented in that way doesn't mean you understand the risks of high pressure and breathing gas chemistry.

Enjoy the journey. I seriously doubt you are spending the mortgage money on this so if you waste money and learn lessons that will be part of the deal. Those warning you off from the endeavor are just trying to save you some grief that you are quite willing to accept.

 

[formernuke]

I would not want my compressor in a completely different place than the tanks I'm filling. Both require my oversight. With my setup which is a rix continuous blending nitrox into a bank of 4 big bottles and filling tanks from there or filling both at the same time, I need to be watching the fills, the compressor and the O2 content while also draining condensate and being close to the shutoff switch and yanno, maybe a fire extinguisher.

I'm not seeing how to make this work on multiple levels of your house but I also would never try to talk you out of having your own setup. I don't trust people at dive shops to fill my tanks, I'm a long way from a dive shop and I am particular about how things get done so owning my own was just going to happen. It helps if you are handy at fixing things but study up on this because being a good mechanic and being talented in that way doesn't mean you understand the risks of high pressure and breathing gas chemistry.

Enjoy the journey. I seriously doubt you are spending the mortgage money on this so if you waste money and learn lessons that will be part of the deal. Those warning you off from the endeavor are just trying to save you some grief that you are quite willing to accept.

Maintenance on the high pressure air systems was part of my job in the military so I'm aware of the risk, that's why I swore I wouldn't have one in my house.

I'm trying to make it work with my house setup and a mini running around. Not ideal but what in life is.

 

[iain/hsm]

There is'nt a such thing as O2 safe air from a oiled compressor.

There is'nt such a thing so I fixed it for you.

 

[iain/hsm]

I want to set up a single large bottle bank at 4500 run through a reducer that I can set for the pressure depending on which tanks I'm filling.
I do dive nitrox sometimes

To kick off dont fall into the trap of thinking your a pretend fire station or dive shop if your just filling for private use at home.

These fire house guys are "sold" a 'BRAND" system from a salesmen on commision, hungry salesmen who's best interests are met by a big expensive compressor and with a continued expensive service agreement for parts and labour. Besides jacking the bank up to 4500psi each day every day adds additional wear and tear on your compressor that you dont need and guess what they are now at 6000psi which is why your getting ex fire house pumps cheap.

Your first consideration IMHO is do you really need 4500 psi in the storage tank/s.
Dependent on the storage tank volume V1 and the storage tank pressure P1 and the number of cylinders in the bank
You can simply use the bank as a bulk dump filler into your scuba cylinder V2 and
use the compressor to boost from the decanted residual dumped pressure up to the required final pressure P2.

Then the compressor can continue and fill back up the storage tank to this proposed lower pressure.

You tell us the size of your scuba cylinder/s V2 and the working pressure/s P2 and the number of cylinders in yur proposed bank and we can do the maths.

But for a standard 80 scuba cylinder at 3000psi (11 litres by volume water capacity at 207 barg pressure )
And assuming storage bank cylinder of 50 litres volume at 2500 psi (140 barg) pressure.
The choice you have with a single cylinder 2500 psi bank is either or:

But first off do you want to be jamming all day into the thing trying to get 4500 psi so you can make a fill in a 3 minues flat charging rate like a fire house does or would you be content to dump say from 2500 psi to 2000 psi into your scuba cylinder from the bank and then wait 4.75 minutes while the compressor tops it off to make the 3000psi both options make the same fill. Your call.

 

[formernuke]

I have hp 100's so 3500, lp50's doubles and AL 80 so 3000 likely I won't be filling the 80's though.

Plan on either 2 sets of 50's or 2 100's

 

[iain/hsm]

And to finish off the maths after your 4.75 minutes with the compressor running topping up your cylinder to 3000psi you now continue running it to refill the bank cylinder back up from 2000 psig (140 barg) back to its original stored pressure of 2500psi (172 barg)

That requires putting back 1600 litres of gas and using a Rix SA-6HP that will take you all of 10 minutes.32 seconds
Time to make a cup of tea sit back with a biscuit and read the first few pages of your newspaper of choice.