Tuning Benjamin Marauder Gen2 gauge is not showing right pressure

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airgun14

airgun14

Member
Mar 21, 2020
134
1
dalarna, Sweden
Hi, degased my Marauder today, just wanted to check how the tube was looking inside after 6 years, it looked really good and shiny, so I put the front cap on, then filled some air slowly, and noticed for the first time that the gauge on the gun when reached 3000psi, it was only 160 bar on my scuba tank gauge wich i know for sure is exactly spot on since I fill in in my nearby diver store, and they told my my gauge is showing 100% correct, Yeah I know its strange Ive never noticed this before, but Ive always looked at the guns gauge when filling and to be honest I have not been shooting this gun so much either.



So now to my question: would you stay @3000psi on the guns gauge, or go to 200 bar looking at the scuba gauge?

It just feels strange filling the gauge on the gun to 3700psi even knowing it is only like 200bar, Ive never done it, thats why Im asking how you would approach this? 😨




 
Before you get too worried, be aware of the ideal gas laws that are coming into play. As you fill the empty tank on your gun the pressure increases and thus the temperature assuming the volume stays the same...and it does, unless you rupture your tank, and that is a whole different issue.

So after you fill the gun its temp is higher, thus raising its indicated pressure.



So, what to do....

Fill the tank slowly...now let it sit for awhile...hour should be fine. Now go back and hook your tank up and add just a little more air, so that the line between the two is now equalized with out too much air pressure change to cause a temp change.

Check the two guages and see if they are now a little closer.



Keep in mind if your gun guage is reading high...you could be overfilling. Google ideal gas law for the PV = nRT relationship you are experiencing. 

Hope this helps.
 
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Yes I know about the heat adding like 5 bar, then it settles down, and Ive tried 2 different guns also, my Artemis shows 205 bar when my tank shoes 200 bar, and my BT65 shows 187 bars when my tank shows 200 bar, and this is right as I remember my BT 65 showing low.



Tried 2 times fill the Marauder, same thing, I dont worry Im just a little bit supriced as almost 40 bars wrong is pretty much. If I where to fill to 200 bars then the gauge on my Marauder would not have enough scale as it would be over 3500psi on that gauge.



I will keep it to 3000psi on the Marauder Gauge as I always have
 
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I agree fwiw. I did just go get my .25 marauder that has been sitting at 1500 psi for over 10 months! Topped it off slowly to 1700 psi...best guess on that small guage. Comparing to the tank pressure, there was about 125 to 150psi variance between the two.

The marauder does not have a very precise guage installed, probably to allow more $ to be spent on making the gun more accurate. I can live with that personally 😁.

You can always hook up your tank after everything cools off and get a better feel for what the true pressure really is, or invest in a better guage?

Hope this helped. Stay safe.
 
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ok, so i did disamble all again, wanted to remove the valve and gauge part to put in new orings, this time when assambly I did tighten the gauge as loos as possible, still the same...... also noticed when there is no pressure the gauge shows 250 psi, so maybee something is not quite right with this gauge.... well i will let it be for now, and fill to 3000 psi, 
 
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