First Compressor! GX CS4 Initial Impressions

12/4/23 UPDATE: now have over an hour of time on this, many fills later with zero issues so far. Filling my crown to 250bar every time and stopping with the auto stop perfectly. Hopefully this continues!

I recently got back into PCP's and decided its time to ditch the hand pump and get a compressor. I did a ton of research before choosing but ended up going with the GX CS4 mainly due to the liquid cooling while still being portable.

This is my FIRST compressor and I am aware there are far more expensive and better options for some, this was my choice. I am posting this so those looking into THIS compressor can get an idea about it. So any positive/negative feedback is welcomed but please be sure it pertains to THIS UNIT ONLY.

Yesterday I finally got the CS4 in and here are my initial impressions:
  • Design Quality- Seems very well built overall, I didn't expect it to have a premium feel but it seems (initially) to be built respectably. I really like how the inverter is exterior and separate of the unit. I saw a lot of complaints about this but to me this makes more sense. If I want to go portable, why would I want to lug around the inverter inside the unit? Its added weight, plus its harder to get to in the event I need to maintenance/replace. The 12v cords for using it in portable mode seem to be quality lines, although not thick like jumper cables would be. The switches/buttons/gauges all make sense and I really like how you can switch the pump on, and or leave it run after you are done filling to help circulate and cool the unit. The gauges have both Bar/PSI so it makes it easy to reference, some units I was looking at did not have that feature so that's a nice touch. It has rubber feet on the bottom and on the side as I imagine you can lay it over but I am not sure how that would affect (if at all) the water pump. NOTE: This unit DOES have a burst disc by the grease pot which I read some smaller compressors do not have. Definitely wouldn't operate one that doesn't have one, but maybe that's just me.
  • Initial start up- Obviously read the manual prior to doing anything with a high pressure unit like this, but also double check all the screws and fittings and such just to be sure its going to be a safe start up. I am not a safety Nazi by any means but high pressure and loose objects usually tend to become projectiles. At any rate, I started by dumping the fluid that was in the water revivor as I received it. I read a few blog posts on this unit before receiving it and that seemed to be the standard as these are all QC'd for function before leaving the factory. There looked to be some sediment floating around so I just flushed it by pouring in distilled water, swishing it around and then dumping it out. Repeated this like 2-3 times and called it good. I refilled it will just distilled water at this point, however I do have the antifreeze on standby now that I have confirmed the unit operates correctly. I double checked the inverter was set to 120v (Do not forget that step) and then filled the water reservoir until full, next you need to start JUST the pump and the continue to till until the water reaches the outlet flow up top. Now I knew I was ready to test the unit.
    • Did the whole start up process with the plug in the supplied air line and filled to 250 bar, achieved by setting the needles in the desired location. Then once filled I let it sit in the line to check for leaks...I had leaks. HOWEVER I checked the fittings and discovered it was the plug itself which was letting air escape and not the hose (confirmed by trying a spare hose I had on my hand pump). Decided its time to test it on a rifle and see what it can do!
    • First gun fill: Xisico Sentry OG model- The gun was sitting at around 1200psi and I needed to fill it to 2200 psi for my current tune. I have no idea what size the air cylinder is but one of these airgun nerds will surely chime in :). Once again did the whole start up procedure (too lazy to write it out) and started filling the gun, it filled it to the desired pressure and stopped dead on the money in under 2mins. This to me was fairly impressive however I have never even seen an HPA compressor in action so maybe its just me. What was super surprising was the noise level of the this compressor, it was super quiet and very smooth sounding. It sounded as if it was barely doing anything and maybe thats due to such low pressures on a unit capable of much higher. Anyways it worked great and the sound was quiet enough you can run this inside no problem.
  • Today and in the days to come I will be recording a video of it filling my Crown with a bottle on it to 250bar and see how it does. Overall I am really impressed and happy with the purchase however time will tell. My absolute main concern was not noise level, or time to fill, it was simply life expectancy. These things aren't cheap (at least to me) and I need/want it to work. I posted a couple pics of the unit (not the greatest lighting in my basement) and like I stated above, will have a video link shortly (not a youtuber so don't expect much) but it will show case the start up process and how it fills a larger bottle gun.
NOTE: The hose on the unit is NOT the one that came with it, so don't expect to get the larger dessicant tube on there, this is the hose from my pump. The one that comes with the pump does NOT have a desiccant tube.

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Here's hoping yours lasts a good long time. If cared for properly it should. Just be sure to never start the motor without the purge valve open. You can strip the gears if you do.

Because it is a 4 stage compressor it can move more air at lower RPM / SPM, which is probably the main reason why it is so quiet. I haven't had mine very long but I like it a lot better than my Yong Heng, though I or one of my kids still use the YH as well to fill guns and tanks. If you hook it up to a silent 12v power supply that has enough amps, it is even more quiet. The power supply makes quite a bit of noise.

The water trap in the CS4 is very effective. I would recommend purging it while running with a short blast of air then close it quickly, every 5 to 10 minutes in fairly low RH areas. Sooner in high humidity locations. You can test it with some color changing beads in that little blue filter you have. Just don't leave them in there for a long time unless they are in a plastic tube to prevent contact with the aluminum. If you purge it frequently, not much moisture will get past it. If I don't purge for 30 minutes or more with moderate RH (30%?), sometimes it will fill up and start pushing water into my big water trap.

I hooked up an "Orange" coalescing water trap first in line after my CS4, followed by a large gold Tuxing molecular sieve for topping off my SCBA tanks from 3000 to 4500 PSI from time to time. As long as I don't run it too long, not a single drop of water has come out of the known to be very well designed "Orange" traps. I installed a one way valve right after the compressor, a shutoff valve and bleed screw on the gun side of the water trap and sieve. See more info here.
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Because it is a 4 stage compressor it can move more air at lower RPM / SPM, which is probably the main reason why it is so quiet. I haven't had mine very long but I like it a lot better than my Yong Heng or my CS3 though I or one of my kids still use those as well. If you hook it up to a silent 12v power supply that has enough amps, it is even more quiet. The power supply makes quite a bit of noise.
That’s a good point! I never thought of that. I’m hoping it holds up because it seems great.
 
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That’s a good point! I never thought of that. I’m hoping it holds up because it seems great.

I also have high hopes for several years of use. I will be happy if I get 3 years out of it. With more friends and family members getting into airguns, I will probably soon buy a shared ownership high dollar machine that will fill large tanks easily and save the CS4 for just filling guns directly and to take on trips as a backup for when my tank runs dry.
 
Congrats on your purchase. I’ve had mine for a few months now and has about 8 hrs on it. It’s great away from home, my Omega Aircharger is the main stay with about 30 hrs on it. This little compressor tops my 45min bottles with no problem. Nice to have unlimited air!! Enjoy! May you shoot straight and never have any wind! Grassguy
 
Here's hoping yours lasts a good long time. If cared for properly it should. Just be sure to never start the motor without the purge valve open. You can strip the gears if you do.

Because it is a 4 stage compressor it can move more air at lower RPM / SPM, which is probably the main reason why it is so quiet. I haven't had mine very long but I like it a lot better than my Yong Heng, though I or one of my kids still use the YH as well to fill guns and tanks. If you hook it up to a silent 12v power supply that has enough amps, it is even more quiet. The power supply makes quite a bit of noise.

The water trap in the CS4 is very effective. I would recommend purging it while running with a short blast of air then close it quickly, every 5 to 10 minutes in fairly low RH areas. Sooner in high humidity locations. You can test it with some color changing beads in that little blue filter you have. Just don't leave them in there for a long time unless they are in a plastic tube to prevent contact with the aluminum. If you purge it frequently, not much moisture will get past it. If I don't purge for 30 minutes or more with moderate RH (30%?), sometimes it will fill up and start pushing water into my big water trap.

I hooked up an "Orange" coalescing water trap first in line after my CS4, followed by a large gold Tuxing molecular sieve for topping off my SCBA tanks from 3000 to 4500 PSI from time to time. As long as I don't run it too long, not a single drop of water has come out of the known to be very well designed "Orange" traps. I installed a one way valve right after the compressor, a shutoff valve and bleed screw on the gun side of the water trap and sieve. See more info here.
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I have that tuxing filter bleed valve unit. What's dangerous about the bleed valve? Looks lime same kind they have on their compressors. Curious. If you are right will replace in a hot minute.
 
I have that tuxing filter bleed valve unit. What's dangerous about the bleed valve? Looks lime same kind they have on their compressors. Curious. If you are right will replace in a hot minute.

See this post. The bleed screw is made of plated brass not steel and the threads stripped off, shooting the part into my hand with a lot of force, though the skin was not damaged. I replaced every one of them I had that were from Tuxing with that unit from ebay. An as yet undamaged one is on top in the photo below. Tuxing offered no solution other than to send a replacement of the same improper design.

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I actually ordered one as I liked that it could fill large bottles should I decide to get one down the road. This was the only one that was rated for that when comparing it to others in the same price range. I also figured that if it was built to withstand doing that, then it should be able to last longer when filling nothing but small bottles or rifles. Time will tell.

When you say it was 25 minutes total time, is that how long youve run your compressor so far or how long it took start to finish to fill your crown? Did you use an anti freeze in it or not? Did you see the need to do as geezerhood posted above to no lose pressure when refilling several rifles/bottles at a time?

When I was ordering my rifles from AoA, they did suggest an omega cleanair inline filter. As he said, if you are going to be spending alot on rifles you want to protect them. I dunno if it was marketing or not, but it did make sense too. Especially as I expect to buy another rifle or two or five lol. I do want every safari offering daystate/brk releases as I love the looks of them.
 
I actually ordered one as I liked that it could fill large bottles should I decide to get one down the road. This was the only one that was rated for that when comparing it to others in the same price range. I also figured that if it was built to withstand doing that, then it should be able to last longer when filling nothing but small bottles or rifles. Time will tell.

When you say it was 25 minutes total time, is that how long youve run your compressor so far or how long it took start to finish to fill your crown? Did you use an anti freeze in it or not? Did you see the need to do as geezerhood posted above to no lose pressure when refilling several rifles/bottles at a time?

When I was ordering my rifles from AoA, they did suggest an omega cleanair inline filter. As he said, if you are going to be spending alot on rifles you want to protect them. I dunno if it was marketing or not, but it did make sense too. Especially as I expect to buy another rifle or two or five lol. I do want every safari offering daystate/brk releases as I love the looks of them.
Yes I went with this so that I could potentially fill small bottles like a pony bottle or something and not blow it up!
25mins is how much time I have in it total. It takes about 2mins to fill my Xisico Sentry and 4mins to fill my FX Crown with a 480cc bottle.
I picked up some Preston’s antifreeze as it had the lowest PH level in its pure form and then did a 70/30 mix ratio with distilled water. It wasn’t exact as there was still quite a bit of water in the water pump and lines when flushing it out but it’s close enough. I filled my crown and then my dads gun back to back and the coolant was hardly Luke warm to the touch.
I’ve used it with my vehicle a few times and at home with no issues so far. I never start it under pressure (start with bleed screw open) and I always let the pump run for a few mins after refilling and the fan on the inverter (if using it) to run a few mins. Better safe than sorry I guess lol
 
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Yes I went with this so that I could potentially fill small bottles like a pony bottle or something and not blow it up!
25mins is how much time I have in it total. It takes about 2mins to fill my Xisico Sentry and 4mins to fill my FX Crown with a 480cc bottle.
I picked up some Preston’s antifreeze as it had the lowest PH level in its pure form and then did a 70/30 mix ratio with distilled water. It wasn’t exact as there was still quite a bit of water in the water pump and lines when flushing it out but it’s close enough. I filled my crown and then my dads gun back to back and the coolant was hardly Luke warm to the touch.
I’ve used it with my vehicle a few times and at home with no issues so far. I never start it under pressure (start with bleed screw open) and I always let the pump run for a few mins after refilling and the fan on the inverter (if using it) to run a few mins. Better safe than sorry I guess lol
Thanks for the info and its appreciated. I agree being gentle on it will pay off in the long run.

I ordered mine off amazon as I got an $80 off coupon so got it for $600. They sent me a mail detailing the care of it. They sent me a link to a zerex antifreeze but it was $26 for a gallon. I'm looking at alternatives.
 
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