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01-20-2019, 08:00 AM
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Join Date: Dec 2013
Location: Louisville, KY
Posts: 45
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Air compressor won't stay at configured level
I don't understand my air compressor's regulator ? When I set the output pressure to something lower, like 40, it will initially shoot out at 40, but within seconds the output pressure will fall to close to zero. If I modify the output pressure while continuously using it then when I stop using the air it will creep up to something like 100. Then when I use it again it will initially start out at 100 and then quickly drop down to the 40 which I initially wanted.
What's going on here? Is this how it's supposed to work?
I can make it work with my rivet gun if I'm careful, but it's certainly not ideal. Are there ways around this? I also have a brass inline regulator on my rivet gun but I don't understand it yet. Too many variables. Ugh.
__________________
Guido Bartolucci - Louisville, KY - Bowman Field (KLOU)
RV-8 (N883G): Empennage Finished, Working on Wings
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01-20-2019, 08:08 AM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Assuming the regulator is working correctly, it sounds like there is a restriction to the airflow------small diameter hose, too long of a hose, kink, or flap of the interior liner of hose blocking flow.
I would check the above, if all good then it could be a bad regulator.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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01-20-2019, 08:15 AM
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Join Date: Dec 2013
Location: Louisville, KY
Posts: 45
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Thanks Mike. I just checked and no kink and nothing that looks abnormal from the outside. I guess this is a good time to replace it one of those super lightweight hoses that I've seen and see how that works. Are there any inline regulators that work particularly well for riveting?
__________________
Guido Bartolucci - Louisville, KY - Bowman Field (KLOU)
RV-8 (N883G): Empennage Finished, Working on Wings
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01-20-2019, 08:29 AM
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Join Date: Jun 2010
Location: Sunman, IN
Posts: 2,189
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Regulator
I have several regulators from Harbor Freight. I use the small ones, and install a male fitting in one side and a female in the other. The regulator then plugs into the compressor and the hose.
https://www.harborfreight.com/14-in-...uge-68226.html
Each regulator is set for a specific tool, i.e. 3X gun, 2X gun, squeezer...once they are set, I never need to change the setting, only the regulator.
As for the pressures, the running pressure on the gauge will always be lower than the static pressure. Set the regulator for the running pressure...
__________________
Bob
Aerospace Engineer '88
RV-10
Structure - 90% Done
Cabin Top - Aaarrghhh...
EFII System 32 - Done
297 HP Barrett Hung
ShowPlanes Cowl with Skybolts Fitted - Beautiful
Wiring...
Dues+ Paid 2019,...Thanks DR+
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01-20-2019, 08:37 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Not sure it is a regulator problem . .
When reducing pressure from high to low with the regulator, it does not always bleed off the air in the hose/pipe. Try an air blower or tickling the trigger to discharge the air in the hose/pipe then turning the regulator up to the desired pressure.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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01-20-2019, 09:02 AM
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Join Date: Dec 2013
Location: Louisville, KY
Posts: 45
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Quote:
Originally Posted by BillL
When reducing pressure from high to low with the regulator, it does not always bleed off the air in the hose/pipe. Try an air blower or tickling the trigger to discharge the air in the hose/pipe then turning the regulator up to the desired pressure.
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Alright, I just tried this with an air blower and it still does the same thing - After I stop using the tool the output pressure creeps up to a much higher setting.
__________________
Guido Bartolucci - Louisville, KY - Bowman Field (KLOU)
RV-8 (N883G): Empennage Finished, Working on Wings
Last edited by guidoism : 01-20-2019 at 09:02 AM.
Reason: a to an
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01-20-2019, 09:12 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by guidoism
Alright, I just tried this with an air blower and it still does the same thing - After I stop using the tool the output pressure creeps up to a much higher setting.
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A true pressure regulator should not do that. It should recover to the higher setting nearly immediately. It is normal for a little pressure drop during flow, but it should be less than 10 psi. The drop will be flow dependent, so a fully open hose or blower will drop more than a squeezer for example.
There are many small regulators available with various input/output size connections. HF, Grainger, Lowes, HD etc. If there is not a restriction somewhere, then it sounds like a bad regulator.
Lets just review for clarity though . . the input to the regulator is from a receiver tank at say 100, 125, 150, 175 psi. The output of the regulator has the pressure gage. The hose is connected directly, or with a quick coupler, to the output of the regulator. If all these are correct, then back to a bad regulator.
One last possibility, is that some debris has fouled the regulator passages. Some can be dissembled and access the diaphragm and valve. You might check that if it is possible.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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01-20-2019, 09:33 AM
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Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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Details needed.
You say "compressor's regulator". Is that what you literally mean? If so, and the tank pressure is going tens, or even a hundred psi above the set pressure, the regulator's bad (likely dangerously bad).
I suspect you're talking about a secondary, in-line regulator. If that's the case, You need to be specific about whether it's a true regulator, or a variable restrictor orifice, which is common on rivet guns.
If it's a true regulator, what is the gauge monitoring (pre or post regulator)?
Your symptom description almost sounds like you have a restrictor orifice, followed by a gauge. A restrictor orifice will allow downstream static pressure equal to source (tank or upstream regulator), and downstream pressure will drop proportional to size of orifice and flow through the tool.
Charlie
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01-20-2019, 09:33 AM
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Join Date: Jun 2010
Location: Sunman, IN
Posts: 2,189
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regulator
ALL of my downstream regulators read a higher static pressure.
Set the RUNNING pressure appropriate for the tool you are using and don't worry about the static pressure.
As in a previous post, set a low pressure, activate the tool, increase regulator pressure to what is appropriate for the tool, leave it there.
When I get to the shop today, I will take a photo and post it...(or try to)
__________________
Bob
Aerospace Engineer '88
RV-10
Structure - 90% Done
Cabin Top - Aaarrghhh...
EFII System 32 - Done
297 HP Barrett Hung
ShowPlanes Cowl with Skybolts Fitted - Beautiful
Wiring...
Dues+ Paid 2019,...Thanks DR+
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01-20-2019, 10:02 AM
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Join Date: Dec 2013
Location: Louisville, KY
Posts: 45
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This is what I have
Here's a video of what it is doing with an air blower: https://youtu.be/IyVJu_UIbKk
and this is what it looks like:

__________________
Guido Bartolucci - Louisville, KY - Bowman Field (KLOU)
RV-8 (N883G): Empennage Finished, Working on Wings
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