Homefill math

[Greymatter Glass]

So I am looking at putting together a Homefill system for a customer of mine, and have found a few things that concern me based on what I've been told by the salesman I'm dealing with.


The torch this would be running is a GTT Mirage which I am informed has a maximum flow demand of 26 lpm.

The homefill system on an Invacare platinum concentrator only supplies 2 lpm to the compressor. A 5 or a 10lpm unit has the same 2lpm high pressure bypass on the back.

This would give a user about 1.8 hours a day of torch use assuming a maximum flame (marbles, large sculpture).

Even if the larger flame is only on 50% of the time he's working, that's less than 4 hours work per day.

He wants to get 12-14 hours a day on the torch 4-5 days a week. He's a production marble maker, so the bulk of his torch time is spent working on the biggest flame he can tease out of the torch....


I've seen some people here set up the homefills for larger torches, so what's the deal? how do I pull ~15-18k liters of oxygen out a system that only supplies 2880 liters per day?

Can the compressor handle higher throughput than 2lpm? If so, how much?

[Emmett's Glass]

Either he needs several homefill systems or take time off or only use it to supplement his oxy needs.
E

[Mac Maestro]

As far as Invacare units go: The least he could get away with would be a large concentrator (platinum XL, 10 lpm, or larger) with the modification done to it. (turn up the inner regulator). There is a thread on this forum to DIY.

Then run one homefill from the front port, and another homefill from the back. (only invacare has the back port) Then obviously those run into a large holding tank or inline tanks. I've got no math for you, too lazy.

[Emmett's Glass]

You can't hook the front port to the homefill system. The concentrater freaks out.
E

[Greymatter Glass]

yeah the compressor needs 15-20psi input, the front only offers 3-5psi.

I'm curious as to the maximum input flow of the compressor...

[jr23]

So how many homefills/cons do you need to push a mirage full time 6-12 hrs a day.

I don't like going to town and thought about these systems and always wanted a person that uses a a lot of gas would go about making it work.

[Swampy]

OT but might be useful later...

Doug when you come to calculating the current volume of your storage tank, someone posted a jazzy java script somewhere but using a nuts and bolts formula, it goes like this;

Current tank pressure (800 psi) divided by Tank rating (2000 psi) multiplied by Tank volume (220 cu ft) equals current volume available (184 cu ft)

[kq9ak]

Is he making little marbles or 2in and larger

[Greymatter Glass]

Is he making little marbles or 2in and larger Probably 1.5" average, some bigger some smaller.

I'm just gonna have to tell him a homefill isn't going to work.

By the time he gets enough units to do the work he wants he may as well buy a Pro8 or something.

[jr23]

Darn I was looking forward to hearing a guy could rage with these systems. I thought people where out there making a k tanks worth a day with a homfill a oxycon and two tanks bundled. The guys hog wild about these systems threads make it seem like they work every day rage and love it.

[STROKER]

doug,
i have two complete homefill systems that are filling 3 ks at a time.
this is plenty of o2 for me to put in a long day at either the bench or the lathe. delta or mirage depending on where i am working.

if they are all filled to approx 12-1500 psi before i start and i let the machines run the entire time im working : i have yet to maxx out my system. i have run it very low and it that is when it can be a drag. the systems take soo long to refill from nothing so that is why i use a bank of tanks and try to keep it up to at least 800 psi all the time.

i have to let my homefills run practically 22 hours a day to keep up on a solid work week but i have never had to stop and fuck off because i ran out of o2. not that that would happen since i also own a pro8 which can make full supply in just 20 minutes and i can actually torch in about 10 from the time i turn it on.

if you are using alot of outter flame for extended periods then i guess it could certainly eat it up but most of us dont need that much heat for too long even when doing mibs.

i love my pro8 system but it requires a very high end compressor (mine is a rotary screw) and the initial $ to set it up is a fraction of that with a homefill system.

caveat: the homefill while it works well at getting my the higher pressures i want and can not get from the pro8. they are pieces of shit that are gonna break.
compare the o2 making parts of that machine to the ones inside of my pro8 and you would understand my comment.

liquid isnt an option at my shop(they will not deliver) and i go through more than a k a day in the shop so i aint going and exchanging 5-7 tanks a week if i dont have to.

i see the homefills as a great temporary working item and when they break, throw it away and replace accordingly.

mine are all very low hours units to start(under100) and one of them is making a clunking noise in the piston area. still works though soooo.

p.s. doug i am gonna call you back this afternoon. i lost my phone about a week ago and just found it last night with a ton of missed calls.

[Hollister]

Mine broke and I had it repaired. It cost 250. It has never run better. Homecare Technical Services Inc. These people were easy to deal with. They sent back my homefill and I had to call them to remind them to bill me. In some situations it might be worth fixing, rebuilt homefills go for over 2k.

[Aussie]

^ yeah,. what Jay said

I've got a mirage and my gf has a phantom, we run them both off the same bottle and generally the fill stops while we still have some oxy in the one we're using. We can run into a bit of trouble if we're both running large flames a lot. Our G tanks are a bit larger than your K tanks. I have a little E size handy just in case we're pounding through the oxy. I can highly recommend an emergency bottle, but he's going to have to be using the outer flame a hell of a lot to be eating this much oxy.
I seem to have lucked out with the homefill pump I'm currently using for my fills. It has brass components inside as opposed to all aluminium and I've been running it pretty much 24/7 since August last year.

[Aussie]

oh, afaik my concentrator is an m15 millennium. When I start the system, I turn the concentrator to 2lpm until the homefil starts, then turn it right down to 0lpm (zero lpm) to keep it going and it works. If I keep it up on 2lpm, the compressor will stop, say there's not enough oxygen and then restart once the reservoir bottle in the homefill is back up to pressure, but at 0lpm it runs constantly.

[Aussie]

could even be an m10, but I'm not sure. I removed the aftermarket UO labels so I could see the factory labels, but UO painted over them. I can just make out the "millennium" bit

[elad65]

Maybe customer needs the bigger style system Like the RIX compressor coupled to large storage (K tanks on manifold) and large (maybe 2) 15 lpm concentrators supplying them. Could be home fill is just not big enough, some times you just can't get past certain mechanical design limitations.

Elad

[Greymatter Glass]

I'm encouraged that I know how some of you work and are doing this on Homefills. I think he said he has 5 tanks, so if he were to manifold 4 and keep one spare he might do ok.

Aussie, what do you mean you turn down your concntrator to 0lpm? I was told the Invacare Homefill system needs 2lpm at ~15-20psi to function.

[Mac Maestro]

You can't hook the front port to the homefill system. The concentrater freaks out.
E

You CAN plug into the front, and should - if you do the concentrator modification. Your lpm meter will no longer give good measure, (and the meter will "freak out") but if you've done the mod correctly you know what pressure is coming out. Check the DIY concentrator mod thread.

[Aussie]

I'm encouraged that I know how some of you work and are doing this on Homefills. I think he said he has 5 tanks, so if he were to manifold 4 and keep one spare he might do ok.

Aussie, what do you mean you turn down your concntrator to 0lpm? I was told the Invacare Homefill system needs 2lpm at ~15-20psi to function.

I'm not even going to pretend that I know how this works, Doug, but that is how it works. Just following the instructions from UO for the original system. Maybe the pressure lessens at higher flow output? .... all I can tell you is 0lpm works and 2lpm stops and starts. I can take a vid for you but all you would see is the system working really well at 0lpm ... spooky, right?

[Aussie]

I had a think about this under the shower
perhaps increasing the flow rate also decreases the pressure and pressure is the more important factor in the equation that triggers the Homefill. When the flow is at 2lmp it fills up the reservoir in the homefill, the homefill starts and the concentrator can't keep up the pressure in the reservoir as fast, or faster as it's being drained. Thus it stops and only starts again once enough pressure has filled the tank. While the flow rate at 0lpm is lower (but not actually 0) the pressure may be higher, thus keeping the res tank filled to optimum pressure.
I don't have testing equipment so I can't tell you if my theory holds water or not, but considering that flow rate is volume/minute, it's not so far fetched to think you can have a high flow rate at low pressure or a low fill rate at higher pressure ....

[Swampy]

...Check the DIY concentrator mod thread.

Here's the thread (http://www.talkglass.com/forum/showthread.php?t=40974&highlight=concentrator+mod) my learned friend Maestro is referring to.

[drew1492]

I think it sounds like two homefills could work good for them. Linking bottles and incresing the input pressure are going to give you better rates. One may do the job I would try one first and see if it holds up.

[metalbone]

I think the 2 lpm number is wrong. I am filling an equivalent of a K in 19 hours using 2 HFs and 2 platinums (it doesn't matter if is the platinum 5 or 10) filling 2 Ks. Dividing by 2, that is 1100 cf of O2 in 38 hours, which is way more than 2 lpm. Also, the Platinum doesn't put out anywhere near 15 psi and it is made for the HF. I upped the PSI on my Platinums, but no way they put out 15 psi...maybe 10 if I am lucky.

FWIW, I was runnung a mirage off the 2 HF system, no problems runnnung uit for 6 hours , still had plenty of oxy let over. I also did the math on the rix microboost a number of years back and it wasn't that much better than the HF, but it was a whole lot more expensive.

[Aussie]

Please disregard everything I said earlier, I opened my concentrator today and everything is not as it appears from the outside ...
The flow adjuster on the front of the unit is connected only to the outlet from a second flow adjuster on the inside of the unit via a Y connector. Opening the flow adjuster on the front to 2lpm in effect bleeds oxygen from the unit. Where does it go? Just to the inside of the casing ... no hose attached ... the output of the exterior flow adjuster just ... opens. In effect, setting the exterior adjuster to 2lpm lowers the pressure until the Homefill unit kicks in, then setting the lpm to 0 increases the pressure to the homefill to maximum ... hmmm.
The interior flow adjuster is set to 2lpm, which I increased a little bit and my setup seems to function better. I also found out that the sieve bed was last serviced in 2001 according to the service label ... I bought the unit in 2010 from UO. Whether UO serviced the sieve bed before selling it to me or not, I have no idea, but it's probably time for me to rejuvenate the sieve bed.

[STROKER]

mr. australia, i was told by the pro8 peeps that the sieve bed material is infinately good if its used in the right way.
moisture is its biggest enemy but under normal use it should have a very long shelf life.

i have seen a guy on the bay that offers seive bed repours for 80$ but i also understand that to be effective the zeolite must be tamped and packed to serious tight tolerence. if you just pour it in, it will work but not for long.

[Aussie]

Good, info, thank you mr. USA! While I know about the homefill backwards, now, I had no idea what the inside of my concentrator looked like until I had a look today.