@sidco @future @cyclopath @Soxhlet @Killa12345
@tokesandtinkery has requested that his GC adventure get split off into another thread, any chance we can do that for him?
I think it might also be time for an “analytical equipment” category. We’re starting to get a lot of these threads and given all the d8 concerns I suspect there’s about to be a bunch more. Seems like everyone and their grandmothers are buying a chromatograph
Speaking of…
Nearly shit myself getting these injectors in, I hope I don’t have to touch these for a while; what a giant pain in the ass. Killed 2 during this install… I’ll blame it on old parts… yeah, old parts
Injectors installed, have not tried to place the auto injectors yet… for fear from last time…
Everything is wired in, next i need to install the columns and I guess start for leak checks and setting up the split ratios flow rates? Maybe @Chaboes or @OBXtracts (and the many others following) has some guidance around that to share? 
Last update for today. Ended up tearing apart and removing the leaky coalescing filter from the zero air generator. I already have a refrigerated air dryer and a 3 stage air dryer before it, I think I’ll be fine and get rid of the leak at the same time.
This is what came out, thing has no gaskets and everything I’ve tried to rig one up for it to be air tight has not lasted. I’m unable to find the original o-rings or spec for them to replace.
Quick connect to make my life easier
Put the cover back on and leak check. Everything looks good. On to the nitrogen generator, just gonna make sure it’s working properly before running it through the columns and…
Because, of course. I was able to get it down to 6% with some cycling, but I’m not confident this is working correctly. Currently it’s pumping the air into a 10 gallon air tank. I’ll check it in the morning and see if we have pure nitrogen or not…
Not entirely sure why this is inconsistently working (I’m entirely sure it’s my fault)
Back at it this morning and not at all surprised to find, the air in the tank was a small amount of nitrogen (dropped from 20% to 17.5%) but no further.
Trying again, and certainly at this point would welcome anyone with experience with these Chinese nitrogen generators.
The manual essentially says to start it with the n2 outlet closed off, wait 10 minutes and verify the flow meter indicates “000” or close to it (was 10-20 last night). That’s supposed to be ‘normal’ operation; supposed to uncap, then tie into the gas lines and its supposed to generate n2 after 10 minutes.
At the moment, I turned it off, and am letting it sit for a bit. Input pressure is around 70-80 psi.
I’m thinking i may need to change the electrolyte solution next. I’m also wondering, i think the water was contaminated (discharge not filtered, whoops) and am wondering if that may be impacting the device as well.
Well, in the spirit of broken things just working - I attribute it to bitching about it.
After coming back to check on it, >20 minutes later, reading is 10. At this point i turned the unit off, discharged the built up gas, hooked it into my 10 gallon air tank and turn the generator back on. Notably. I do not close off the air tank and instead allow it to flow into and out of the tank.
Check back another 20 minutes or so later, checking the output from the air tank; its hard to get a good picture, however i did get readings to 1.1%; i largely attribute this to the inaccuracy of the meter, holding it, and all the mess in between. At this moment I’m satisfied it’s working properly. Machine reads 180ml/minute.
I closed off the 10 gallon tank to begin letting it fill up. My back of the napkin math suggests 3.5 hours to fill up the 10 gallon tank to 1 atmo, the generator will push to 60 psi and if my poor understanding of psi is moderately correct, thats 4 atmo’s and should take apx 14 hours to reach the generators maximum psi output before it turns off.
So, I’m gonna let it do that; take my small compressor, feed the input line into the nitrogen tank, and compress it down. 135 psi compressor, again back of the napkin math suggests the 1 gallon tank should hold about 9 gallons of compressed nitrogen.
Perfect, just in time to fill up my tires 
Possible future problem, find out why the 500ml/min generator isn’t running at its capacity. I’m not complaining, but I do have a glove box I’d like to fill up.
Oh shit, i have another 10 gallon tank i can chain to the first. Mmmm yummy n2
Thinking about this, because I can’t not; this may all be entirely unnecessary.
I had a thought to use a RO membrane housing to act as a kind of seperatory funnel, idea being, connect the n2 input to the second lowest port on the housing, mounted vertically, the top port going to the tank, the bottom most port left open; idea being, oxygen being heavier will fall down and out.
Could further run it into a desiccator and or an activated carbon filter, which, in theory would further remove contaminates including oxygen.
It’s probably unnecessary…
In todays episode of, fucking with the nitrogen generator…
When the day started, my setup was like this:
Frank the tank loud MOFO air compressor → refrigerated air dryer → 3 stage air filter/dryer + regulator → zero air generator → nitrogen generator → storage tanks
I end up removing the regulator from my 3 stage fixture entirely, primarily because I did not have the appropriate 1/2” NPT to push connect fittings (somehow i have 6mm and not 1/4 OD - thanks amazon?).
So, with that being the case, the theory i wanted to this this morning was regulating the output of the generator on the n2 output side; my thought was, the manual specified running it at less than full capacity and i thought i could do it this way.
Well, 500ml/min is apparently just too low for a regular air compressor regulator, with that discovery i removed it all from the setup and ended up now with this:
Harbor freight ultra quiet air compressor → refrigerated air dryer → zero air generator → nitrogen generator → storage tanks.
Using the PSI control at the air compressor i am semi-able to control the output, maybe?
This appears to be an example of a “working condition” start up. After more than 10 minutes, though I did not time it unfortunately, the generator went from reading 0 psi and 080 on the display, to building up to 60 psi, display cycled up to around 400 something and began going down to eventually read 000
After opening the n2 outlet to exhaust the gas and allow flow from the generator, i tested with my o2 meter. I was able to get it below 1% o2 by holding the output line from the generator to the sensor of the meter. Unfortunately it’s too cumbersome at the moment to get a good picture.
Not entirely trusting the generators flow meter, i hooked up my new Agilent flow meter and to my surprise, a 20ml/min variance which I can attribute to sampling rates and level of accuracy of the sensors between the two devices. I’m reasonably confident.
Flow rate is looking good…
Not entirely trusting the high output of the generator just yet, i closed off the storage tank, allowed air to build (knowing there is going to be a mixture of oxygen in the tanks that need purging.
Waited a few minutes then released the built up air and tested it, as I expected the o2 meter shot down from 21% or so to about 17 before climbing a bit before eventually beginning to fall again. At this point I’m pretty satisfied the nitrogen generator is pumping out highly pure n2.
For some dumbass reason the steel air tank (originally got the aluminium, should have gotten 2 of those instead…) has no drain port; so, i have inverted it best I can to better allow oxygen to be purged next time, sparing as much n2 as possible.
Currently I am going to allow this to run. The rate is anywhere from 400-600ml/minute (having no fine controls just yet), the 20 gallons of air for the tanks to move from 0 to 15 psi should take about 2.5 hours by my math.
I will aim to, every 3 hours or so, put my o2 meter in a ziplock bag, and purge the output from each tank into the bag. Once the o2 meter beings to reliably indicate all likely o2 has been purged I will begin to fill up the tanks to their capacity (60 psi, apx 40 gallons n2 each, compressed) and should take something like 10 hours to do.
Next, I need to setup a pressure relief valve inline somewhere so that when the tanks reach 60psi of pressure, or probably less, it will begin discharging into a line which i will direct into my glove box.
I suspect I will need to get a series of heavy duty inline desiccators to further dry out the air prior to the zero air generator
You can always just build a big CRC style tube filled with zeolites. Just curious, how much did you pay for that N2 generator?
For this one, i think it was around $1600 I can get a firm number if you’d like.
That said. I misunderstood the flow requirements and read them as 450 ml/minute makeup gas - thinking it meant n2; there is a 300ml/min model that is quite a bit less around $1000 i believe.
Only reason I mention the 3 stage filter is I ended up removing the coalescing filters from the zero air generator, as they were leaking. At this moment, there are no coalescing filters in the path.
So coalescing filters (by definition) only remove liquid phase contaminates through impingement (demisting) but they don’t actually lower the water vapor content of the air. Using a drying agent achieves both things and is preferable.
Ideally, you’d set up two driers with 3-way solenoids on each side and a heater wrapped around each. Then use a timer to switch which unit is open to atmosphere and being heated (regen) and which is in use. Probably could work something up for $3-400
If I’m not mistaken, you’re referring to a kind of, back bleed heated desiccator.
I bet we could do it cheaply as follows:
One way valve → (maybe a solenoid instead, run opposite [NC vs NO] to the next and on the same timer.) → 1/4 npt TEE with 120v 1/4 npt solenoid WOG → desiccator wrapped in 120v heat tape → dry storage tanks → one way valve → n2 and system + n2 storage tanks.
Probably two timers; one to turn on the heated desiccator first, then the second to open the solenoids to discharge the exhaust
Maybe a 2 inch steel tube with KF25 connectors to npt or otherwise for the desiccator. Probably with a sight glass somewhere to get a visual on its condition.
Perhaps an arduino with 4 relays. First to close off air coming into the system. Second to close off air from the dry storage tank back into the desiccator. Third to activate the heating unit for a period of time sufficient to begin evaporating moisture from the beads. After such period, the fourth relay and the second relay will become open, allowing dry air from the dry air storage tank to purge the moisture from the desiccator through the purge valve opened by the fourth relay.
Could get fancy with it, put a moisture sensor inline.
Was kind of thinking about something like this, with some sensors to make an idiot proof n2 generator startup sequence. Me being the primary idiot of concern.
Fun little addition, no idea what kind of condition it’s in…
Now to figure out if I just bought junk or not…
Wooohooo! Congratulations. Looks like you’ve got CI on there too so that’s neat
Is that the column fitting you’re referring to?
Any idea how I can tell if this thing is alive?
Nope CI is chemical ionization, check it out in the manual. Apparently it allows you to get an approximate exact mass on the eluting compounds which is sweet.
Nothing to do but fire up the MS and see if you can get it to talk to MS Workstation. Get a backing pump hooked up and see if it’ll pump down
Edit: here’s where I found that copy of MS workstation since the zip doesn’t want to upload:
Varian MS Workstation and Win 7 - Page 3 - Chromatography Forum 1
Have you gotten this far?
I installed the workstation software and test database (none of which installed easily on XP for some reason), plugged the mass spec into the usb-gpib and nada. I cant tell if this thing has a built in GPIB address or what
Lol that’s my next step. I need to rewire the MS for 120v first
Oh I forgot to update lol. I finally put the GC back together, mass spec not withstanding, with the auto sampler and tried to run some tests to see if it would do anything.
As best as I can tell the auto sampler injector does appear to be working correctly. Yay for that. However the tray does not move, i get 4 or 5 (hard to tell) flashes on the controller which I believe indicates the radial arm (probably why it doesnt move). Software reports a generic error
So… I’ve ordered a replacement, hopefully it works!
I wanted to get back to this thing, I think it’s a lot more simple than that:
Two spools filled with adsorbant and capped with 1/4 compression adapters (honestly this could be built with plain stainless pipe parts welded up after being cleaned very thoroughly). Let’s call this $25 each for 2x12" which should be plenty.
Connect the inlets to a 3/2 solenoid. Connect the outlets to a 5/3 solenoid (meaning the coil switches which inlet goes to vent and which goes to equipment). Then use a single relay timer with a SPDT contact. When not energized, the solenoids are not energized and the heater on one spool is on. When energized, the solenoids switch and the other heater is energized. Two solenoids at $50 each, relay timer probably $60 for a nice one. Everything 120v so no power supply needed. For heaters, heat tape should suffice, let’s say another $50 to be safe. $40 for fittings into the solenoids makes a total of $350 for the project, plus a little welding.
Fun fact, if we use slightly different media and run the correct pressure, this is very similar to how PSA oxygen/N2 generators work
You know I love me some tinkery!
Been a bit since there was an update, nitrogen problems. Got a new nitrogen generator, plugged it in and tested it:
At the moment I’m waiting for some electrical to get done, hopefully by end of week and then we should be in business
Oh to be so young and optimistic…
Let’s see, gas lines threaded out, had to be replaced. Did that today, hooked up my Restek flow meter to measure how much gas is going to the columns. And? ZERO nitrogen.
Tore the GC apart, again, to trace down the gas lines, see if any were restricting. Nope, can get sufficient flow. Next, started taking apart the injector manifold and inspecting the valves, see how much gas can flow out of them. Can’t quite tell if the issue is there. Ended up hooking the GC up to my tank of compressed nitrogen, currently looks like there are leaks in the FID manifold block. Not sure.
I’m fucking exhausted with this thing.
I was having a flow issue with mine and I think the EFC didn’t like not having a column hooked up so you may look at that. You should also check to see if the original filters can get any flow through them. Does your unit have all mechanical flow valves/regulators or is there some sort of EFC?
