Homefill pressure cut off switch?

**Icarus** · 01-09-2012, 08:04 AM

To maximize the life of my homefill, I'd like to manifold three tanks together, and only run them up to 1000 psi. I modified my whip with a high pressure T and added an up to 4000 psi pressure gauge to see where I'm currently sitting, and then just manually turn them off at around 1000 psi.

So here is what I would like to do. I would like to either alter the pressure cutoff switch in the unit to have it shut off at a lower pressure, or I would like to install a pressure cutoff switch as part of either my manifold or whip, so that when it reaches 1000 PSI, it just kills the power. The problem with that second one would be that the machines alarm goes off anytime it loses power other than having the face switch turned off, but I could deal with that part, as I guess it would serve as an audible note that I'm done filling for the day.

I've done some searching online and on here, but am unable to find anyone else whose done this, and most of the pressure cut off switches I can find are not rated up to the pressure I need. Does anyone have any experience with this, or could point me in the right direction for where to look for switches that are rated for oxygen, and are either set to shut off at 1000 psi, or has a variable setting to I can dial in the pressure I want?

Thoughts?

**Swampy** · 01-09-2012, 08:22 AM

Same here, been thinking of a similar setup over the past few days mate. Considering a digital pressure sensor, linked to some kind of controller (ardunio?) that would switch the pump on and off.

Reason being I didn't want the homefill to be starved of available O2 and suck past the seals...

so thought of a low pressure holding tank from the O2 generator, pressure switch on that to cut in the homefill, pressure switch on the high side to override and cut it off at specified pressure.

Maybe I was overthinking it though, it's still in a gel state but amazing how we were considering something similar eh. Good one.

**brettodie** · 01-09-2012, 08:29 AM

get a timer and just have the power cut off to the machines.

**elad65** · 01-09-2012, 09:08 AM

Go to McMaster-Carr. Search for part number "3427K15" its a 600psi pressure switch for Oxygen Service. Lists for about $100. You might have to consider more volume of tanks and less pressure.

http://www.mcmaster.com

Elad

**Snurf** · 01-09-2012, 07:23 PM

I don't think its needed. My system fills slower wilth three tanks, so when it rarely gets over 1000psi I turn it off for a bit. If your in the shop 5days a week its not hard to keep track . Enjoy that home fillin!!

**Icarus** · 01-10-2012, 08:49 AM

Originally Posted by brettodie

get a timer and just have the power cut off to the machines.

If I fully drained the tanks, that would work out, but I it's doubtful that I'll be fully draining them each time. Still, that's a great solution to the problem.

I don't think its needed. My system fills slower wilth three tanks, so when it rarely gets over 1000psi I turn it off for a bit. If your in the shop 5days a week its not hard to keep track .

Unfortunately I'm not. I work in IT full time, so I'm in my shop in fits and starts. Some weeks I drain more tanks than I do in some months.

Go to McMaster-Carr. Search for part number "3427K15" its a 600psi pressure switch for Oxygen Service. Lists for about $100. You might have to consider more volume of tanks and less pressure.

http://www.mcmaster.com

That is damned close to what I'm looking for. Wish that they had the model that would go from 400 to 4700 with the fluoroelastomer diaphragm, but perhaps it jsut can't withstand pressures higher than that or can't give a reliable reading beyond that point.

I just found this calculator that will tell you the available cubic feet of air based on PSI and holding capacity of a tank (http://www.csgnetwork.com/volumeprestankcalc.html)

and it looks like if I manifolded 3 k (249 cu ft) tanks together and ran them up to 600 psi, I would end up with 203 cu ft of oxy (80 % of one full tank). If I added an additional K tank to the mix, I would end up with 273 cu ft of oxy if I brought it up to 600 PSI.

Ideally I would bring it up to 1000, but I can live with 4 tanks manifolded together instead of 3, and probably making my homefill work much less harder than it would have to even hit 1000 psi.

Thanks everyone for your help. You've all been repped.

Also, that calculator I linked to, that can be used by anyone to figure out how much oxy they currently have available to them in their tank. That's pretty cool in and of itself.

**Swampy** · 02-10-2012, 09:59 PM

^ Thanks for the link to calculate pressure:volume.

**Emmett's Glass** · 02-11-2012, 12:13 AM

So you're saying that if you have 4 tanks at 1/4 pressure it's equal to 1 tank at full pressure?
E

**STROKER** · 02-11-2012, 07:32 AM

^^^in theory i say yes.

i run two homefills on a loop in a 3 k-tank setup.

i have taken one bottle that was filled to 1500 psi while the other two were empty and opened up the 3 valves at the same time.

after a minute to redistribute the gas in the 3 tanks , i had 500 psi across the board.

i keep all my tanks between 1200-1500 psi which gives me more than enough to rage the delta all day long.
with both homefills running it takes about 20 hours to get the 3 tanks to 1000 psi and around 28-30 to get 1500 in the system.

when i go to the glass shop i fire up the homefills and let them run while i work. then i usually let them run during lunch, dinner, and a few hours at the end of the day then i shut down manually.

with just me, i have not come close to running out of o2 with the multi tank setup. just one tank and i would have been on the ragged edge many times over. delta loves the o2.

i open all 3 tanks to work from and even after doing big vac stacks for the day i still had plenty of o2 to play for the night. the lowest i have run the system down to after a long day was about 600 psi across the board of 3 tanks. in theory i still had an almost full single k tank.

if i go that low, then i will let the homefills run overnight to catch the system back up.

i like the homefills but unless you are set up with a multi fill system, it can be a bit of a balancing act to make sure you got the o2 when you need it.

good thing for me is i can fire up the pro8 and be at full capacity in 20 minutes and ready to go for the day instead of 20-24 hours of lead time.

i plan to use the homefills for my bench burners and the pro 8 for the lathe.

**Emmett's Glass** · 02-11-2012, 07:53 AM

Originally Posted by GWS

^^^in theory i say yes.

i run two homefills on a loop in a 3 k-tank setup.

i have taken one bottle that was filled to 1500 psi while the other two were empty and opened up the 3 valves at the same time.

after a minute to redistribute the gas in the 3 tanks , i had 500 psi across the board.

i keep all my tanks between 1200-1500 psi which gives me more than enough to rage the delta all day long.
with both homefills running it takes about 20 hours to get the 3 tanks to 1000 psi and around 28-30 to get 1500 in the system.

when i go to the glass shop i fire up the homefills and let them run while i work. then i usually let them run during lunch, dinner, and a few hours at the end of the day then i shut down manually.

with just me, i have not come close to running out of o2 with the multi tank setup. just one tank and i would have been on the ragged edge many times over. delta loves the o2.

i open all 3 tanks to work from and even after doing big vac stacks for the day i still had plenty of o2 to play for the night. the lowest i have run the system down to after a long day was about 600 psi across the board of 3 tanks. in theory i still had an almost full single k tank.

if i go that low, then i will let the homefills run overnight to catch the system back up.

i like the homefills but unless you are set up with a multi fill system, it can be a bit of a balancing act to make sure you got the o2 when you need it.

good thing for me is i can fire up the pro8 and be at full capacity in 20 minutes and ready to go for the day instead of 20-24 hours of lead time.

i plan to use the homefills for my bench burners and the pro 8 for the lathe.

Why not have the homefill running from your pro 8 when that's on?

Also I heard of a guy who set up a manifold system for a homefill and forgot to open the tanks while filling and left for a while. His manifold got to pressure in no time but the system didn't shut off and his homefill was burnt up when he got back.
E
E.

**STROKER** · 02-11-2012, 08:08 AM

e, the pro8 could act as a feed source but the pressures would have to be seriously readjusted.
the down side to that scenario is that i only run the pro 8 when its needed since it makes and fills my 80 gallon reserve tank in a few minutes.
no need to let the pro8 run anymore than i need to since it can do it job so quick on demand. plus it has no problems keeping up with the needs of a delta at full throttle.

since i dont want to babysit and deal with the on off cycles of the pro8 , i just leave it as is. a completely seperate entity.
im afraid that i too may burn out the homefill from not having my feed source set up to run all the time.
it wouldnt take long to burn out the tiny homefills if they were run with no feed o2.

i do actually have an extra homefill that i am keeping as a spare and i have thought about this scenario several times and who knows maybe one day ill give it a go.

**STROKER** · 02-11-2012, 08:13 AM

side note:
i wanted to see if these things would actually shut down at 2000 psi and in my little experiment it will not go into standby on either of my machines.

i actually filled the 3 tanks set up to 2200 by just letting the system run and run and run.

took forever to get the last 500 psi in the tanks. never went into standby.

since it never shut down i am wonderng if there is some kind of volume control issue while using the big tanks as opposed to the tiny tanks they are designed to fill. just a theory.

one thing is for sure, homefills are very nice. but made to last under these conditions? i think not...

hell my seive beds on the pro 8 are 5 foot tall and 10 inches wide.

probably enough seive material in one tank to fill evey homefill that is being used on here by blowers.

industrial vs. home

**drew1492** · 02-15-2012, 01:49 PM

Originally Posted by GWS

side note:
i wanted to see if these things would actually shut down at 2000 psi and in my little experiment it will not go into standby on either of my machines.

i actually filled the 3 tanks set up to 2200 by just letting the system run and run and run.

took forever to get the last 500 psi in the tanks. never went into standby.

since it never shut down i am wonderng if there is some kind of volume control issue while using the big tanks as opposed to the tiny tanks they are designed to fill. just a theory.

one thing is for sure, homefills are very nice. but made to last under these conditions? i think not...

hell my seive beds on the pro 8 are 5 foot tall and 10 inches wide.

probably enough seive material in one tank to fill evey homefill that is being used on here by blowers.

industrial vs. home

If I was going to run that test personally I would set it up only on one tank so it would take less time and less high end wear on the homefills.

Sometimes thoes gauges are slightly off so there is a possiblity the pressure was right below 2000psi but probably not. I have two gauges on my setup one on each reg and they each read a little different. I doubt it would be caused by the volume but most people use enough oxygen to never have full tanks.

Luckily the systems usually pay for themselves pretty quickly as far as industrial vs medical goes. But I cant wait to get my industrial compressor and fill a K in under 12 hours to 2000psi.

I would love to have a pro 8 setup like you have and just use the homefills a bit. Are they that much more expensive than the new oxygen step up compressor and tank ABR sells?

**elad65** · 02-15-2012, 06:58 PM

I think "volume" is not the correct concept here, everything I have ever read or dealt with was always "pressure".

Elad

**STROKER** · 02-16-2012, 10:54 PM

pretty sure you are incorrect^^^. volume is the correct concept since we are talking about a tank or bank of tanks that is exponentially larger than the tanks the homefills are designed to fill.

the homefills shut off at dead on 2000 psi with the small tanks that come with them and with my k's they went over that mark. by quite a bit. i doubt my gauge is off by 200 psi.

i do think volume has something to do with this equation on the pump. maybe at the top end pressure with those volumes, the tanks begin to apply to much backpressure to the homefill/s pump to adequately shut them down.

the weird part is that my sytem is on a loop with a homefill on each end and neither of them shutdown at 2000. yet when i put a little tank on each one individually, they filled almost exactly the same rate and both shut down right at 2000 psi.
my theory.

**drew1492** · 02-17-2012, 01:01 AM

Originally Posted by GWS

i do think volume has something to do with this equation on the pump. maybe at the top end pressure with those volumes, the tanks begin to apply to much backpressure to the homefill/s pump to adequately shut them down.

the weird part is that my sytem is on a loop with a homefill on each end and neither of them shutdown at 2000. yet when i put a little tank on each one individually, they filled almost exactly the same rate and both shut down right at 2000 psi.
my theory.

I think that volume could have an effect on the homefill, but i do not see how the volume would apply to much backpressure for the pump to shut down? How would volume increase the pressure?

I think this is the part of the homefill that shuts off the homefill electronically.

I am not sure about this but from looking at the inside I think it controlls it, atleast in the newer versions.

Anyways I will leave it at I think people should shut them down at 1500psi. I know you are one smart guy and a talented artist. I think the only one who could really answer this is an invacare engineer.