2 more questions about compressor usage and filters

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glr59

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Sep 23, 2019
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Midlothian, VA USA
You all have been very helpful with my new GX pump purchase. Please entertain 2 more questions.
Is it my understanding that people open the bleed valve on the compressor for a fraction of a second while the pump is filling a large tank?( I have a 9L great white) I assume to release water while pumping? One of my concerns with this is it puts strain on the compressor depressurizing the line and repressurizing it? Am I overthinking this?

Second question, I really need a specific recommendation as to whether I need to add a moisture filter between my compressor and tank and what exactly I should buy.
My understanding as of this moment is it really isn't necessary if I am filling a gun because of the short run time but filling a tank it may be recommended.
Believe me I've spent a lot of time reading threads and I'm just as confused before I started. I believe a molecular seize is the preferred product but I don't want to spend the money right now on one of Joe's alpha filters. I need an economical alternative.

Thanks
Jerry L

P.S I received notice that a new gauge is being shipped from China to replace my defective gauge.
 
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In answer to your two groups of questions:

A) Yes, you are overthinking it . . . you are simply pulsing the pressure to vent the line of liquid water. The pressure will drop a little bit and then recover, as it is flowing back from the tank - it does not drop as much as you think. Your compressor will be fine. If you insist on thinking it is a big issue, then you could put a one way check valve in line before the tank (or preferably the desiccant filter) and then when you open the vent the pressure will drop more (as there will be no "backflow' from the tank) but recover slower and thus put less of a transient load on the compressor (and the check valve will reopen when the line pressure gets back up to the level before the vent action).

B) Yes, you need an air drier when filling tanks. And they are a good idea with guns too, but are a little less critical since the air charge does not get as hot in the shorter runs - but I would definitely use a smaller one for gun fills myself.

If you have not read these two posts (reply numbers 34 and 35) I would do so as it will properly convey the amount of water vapor that you are dealing with in filling a large tank: https://www.airgunnation.com/threads/moisture-in-pcp-airguns.1321274/page-2#post-1839752

Personally, while I like Joe's products in general, I would not buy his Alpha filter - I just don't like his "sales information tactics" on this one, as I feel that they are misleading. If I wanted a known reputable one I would buy this one: https://nuvair.com/personal-filter-din.html

I would have no issue using one of the cheaper Chinese units available on Amazon or AliExpress. And I would likely make my own filter elements with separate media - one can make a cylinder for the beads out of thin plastic film, (like old "transparency" sheets) and use the cotton filter elements as stoppers to keep the beads in the cylinder (likely cutting one into 2 or 3 sections) - and I would get one of the smaller filter housings and do this for filling guns directly.

That said, I don't do any of the above myself as I use an older Shoebox compressor, and do all my drying with multiple desiccant filters on the air after it comes out of the shop compressor, before going into the Shoebox. But if my Shoebox compressors ever die, I'd get a GX-CS4 (or 5) and do what I wrote in the paragraph above here.
 
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glr59 said:
You all have been very helpful with my new GX pump purchase. Please entertain 2 more questions.
Is it my understanding that people open the bleed valve on the compressor for a fraction of a second while the pump is filling a large tank?( I have a 9L great white) I assume to release water while pumping? One of my concerns with this is it puts strain on the compressor depressurizing the line and repressurizing it? Am I overthinking this?

Second question, I really need a specific recommendation as to whether I need to add a moisture filter between my compressor and tank and what exactly I should buy.
My understanding as of this moment is it really isn't necessary if I am filling a gun because of the short run time but filling a tank it may be recommended.
Believe me I've spent a lot of time reading threads and I'm just as confused before I started. I believe a molecular seize is the preferred product but I don't want to spend the money right now on one of Joe's alpha filters. I need an economical alternative.

Thanks
Jerry L

P.S I received notice that a new gauge is being shipped from China to replace my defective gauge.
Click to expand...
The amount of air being bled out is just a cc or 2 to purge the water. I don't think it's a huge loading ordeal with the energy stored in the moisture collector and lines. Just my opinion tho.

As for a dryer. The more filtered and dried your air is, the better. Keep in mind this is even more volume for you to fill with air each time too. It can get to the point where if direct filling a gun you may be doing more work to fill everything before the gun than the gun itself.


Best of luck on your journey.
 
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Check Air Velocity Sport's recent YouTube video on the GX-CS4. He notes use of vertically-placed molecular sieve, on occasion. Appears to be M50, about $60 on eBay. WM
IMG_20221022_234748.jpg
 
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AlanMcD said:
In answer to your two groups of questions:

A) Yes, you are overthinking it . . . you are simply pulsing the pressure to vent the line of liquid water. The pressure will drop a little bit and then recover, as it is flowing back from the tank - it does not drop as much as you think. Your compressor will be fine. If you insist on thinking it is a big issue, then you could put a one way check valve in line before the tank (or preferably the desiccant filter) and then when you open the vent the pressure will drop more (as there will be no "backflow' from the tank) but recover slower and thus put less of a transient load on the compressor (and the check valve will reopen when the line pressure gets back up to the level before the vent action).

B) Yes, you need an air drier when filling tanks. And they are a good idea with guns too, but are a little less critical since the air charge does not get as hot in the shorter runs - but I would definitely use a smaller one for gun fills myself.

If you have not read these two posts (reply numbers 34 and 35) I would do so as it will properly convey the amount of water vapor that you are dealing with in filling a large tank: https://www.airgunnation.com/threads/moisture-in-pcp-airguns.1321274/page-2#post-1839752

Personally, while I like Joe's products in general, I would not buy his Alpha filter - I just don't like his "sales information tactics" on this one, as I feel that they are misleading. If I wanted a known reputable one I would buy this one: https://nuvair.com/personal-filter-din.html

I would have no issue using one of the cheaper Chinese units available on Amazon or AliExpress. And I would likely make my own filter elements with separate media - one can make a cylinder for the beads out of thin plastic film, (like old "transparency" sheets) and use the cotton filter elements as stoppers to keep the beads in the cylinder (likely cutting one into 2 or 3 sections) - and I would get one of the smaller filter housings and do this for filling guns directly.

That said, I don't do any of the above myself as I use an older Shoebox compressor, and do all my drying with multiple desiccant filters on the air after it comes out of the shop compressor, before going into the Shoebox. But if my Shoebox compressors ever die, I'd get a GX-CS4 (or 5) and do what I wrote in the paragraph above here.
Click to expand...
 
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