Have a question on fill procedure from compressor to tank

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Bigragu

Bigragu

Member
Jul 8, 2018
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CA, United States
Hi, everyone. I have a question regarding the procedure of opening a tanks valve when topping off a tank that has a sizable amount of pressure still inside. In my case 3000 to 3400 psi. It is an Airhog 88 cu foot tank. The procedures I’ve read and watched on YouTube all pretty much say when the compressors psi is equal in pressure to the tanks psi, then at that point slowly crack open the tanks valve for the top off procedure. What I’m not understanding, is when I start the compressor up, and it has built up about 800 psi, I see the gage needle on my Airhog tank start to build up pressure, with the valve tightly closed. Not going to lie, this has worried me to the point of opening up the tanks valve way sooner than the equalization of pressure between the tank and the compressor, for fear of backpressure. I do not understand why the tanks gage is in motion when I have the valve closed. My tank is brand new, and it doesn’t leak. 

Is there something I need to be concerned about? Both times I have topped off my tank with my lightning compressor has been successful. Just worried about this needle moving, and no where can I find wordage on that the tanks gage moving prior to pressure equalization is to be expected. Thoughts?
 
Hi. I may not be getting this right so bear with me. Before you fill your tank do you use a deadhead plug to double check your tank pressure? Say its at 3000psi. You connect it to compressor and turn on compressor and try to wait til compressor pressure reaches 3000psi and then open your tank valve to equalize and starts filling your tank? Which is correct for sure. But you say your tank gauge pressure is building before you open the tank valve? This may seem dumb but some tank pressure gauges measure line pressure and not tank pressure so what you are seeing may be correct and working correctly. You would then just open the tank valve at 3000psi and continue pumping til 4500
 
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I usually connect my air tank to compressor, open the tank valve allowing air to flow into the Compressor’s tank. Once equalized I turn the compressor on. Been doing so for 2 years with no problems that I’m noticing, my way seems opposite of what recommended. I believe I read my procedure from the user’s manual that came with my compressor (Omega Super Charger). Based on what I’m reading here I may be in danger or damage. Could someone enlighten me as to the danger or damage that could occur with my procedure?

Thanks

Beach-gunner

Dennis
 
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Beachgunner. From everything i read that doesnt seem correct to me. Im not saying 100 pct. But from what i understand if you do that your compressor has a harder start because it is under so much back pressure and doesnt get to build up slowly. Maybe to be sure you should call where you bought it and doublecheck the procedure. I may be wrong but it would be worth knowing for sure.

I think it may have something to do with the compressor working its pressure up so it can switch to the second stage and not start there.
 
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Beach gunner, for my Hatsan compressor, say I filled the compressor up to 3000 psi, then turn it off, it won’t kick back on till I release the back pressure. And even if it did kick on, that is not good for these things, and can shorten their lifespan. So, in essence, it goes hand in hand with what Crittahitta is saying. Just think of it as the compressor needs to always overpower the tank, not the other way around.



im guessing the reason you haven’t had problems yet, is because your topping off a tank, which could have been below 3000 psi this whole time. If say your tank was at 4200 and you were going to top it off doing it your method, man, that is darn hard on a compressor.
 
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Just read the section on my compressors manual on filling. It doesn’t specify anything about making sure the pressures are equal between compressor and fill tank. All it says is that once the digital gage on the compressor reads 20 BAR, or 290 psi, slowly open up the valve to the fill tank. 

Then below it it say in big bold letters- Caution! the system must be depressurized before turning on the compressors switch.
 
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Hi. I may not be getting this right so bear with me. Before you fill your tank do you use a deadhead plug to double check your tank pressure? Say its at 3000psi. You connect it to compressor and turn on compressor and try to wait til compressor pressure reaches 3000psi and then open your tank valve to equalize and starts filling your tank? Which is correct for sure. But you say your tank gauge pressure is building before you open the tank valve? This may seem dumb but some tank pressure gauges measure line pressure and not tank pressure so what you are seeing may be correct and working correctly. You would then just open the tank valve at 3000psi and continue pumping til 4500
Click to expand...

This is how I do my AV tank with AV compressor, dead head tank to see tank pressure,shut tank valve bleed tank line, hook tank hose to compressor hose then start compressor and let it run untill compressor gauge is the same as my tank pressure then slowly open the tank valve and fill to 4400psi, when compressor shuts down I close my tank valve, turn compressor switch off, bleed air line at compressor, then let compressor run in cool down mode, disconnect the two air lines and then shut the cooling cycle switch off when below 40*, tank is full and compressor is cooled down and then it’s time to go shooting.
 
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