Air pressure

Dave25494

Dave25494

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When I fill my hw100 it says 200 on my air cylinder gauge but it’s roughly sitting at 220-250 on my air bottle gauge is there a problem with air cylinder reading or my bottle gauge or is it including the air in the air hose aswell ?
 
There's clearly a problem with at least one of them!

I'd be very, very careful if one gauge is reading as high as stated as you're potentially overfilling the gun by a very significant amount.

The Wika gauges on the 100 are good quality and generally pretty accurate IME; obviously no idea about your bottle gauge but as a rule these tend to be pretty decent too.

For the time being I'd be reducing the pressure in the gun so that it reads sub-200 on both gauges, and looking for another gauge / gauges to use to verify the readings your getting on your current ones. Do you have access to other filling gear and / or guns with gauges?
 
cloverleaf said:
There's clearly a problem with at least one of them!

I'd be very, very careful if one gauge is reading as high as stated as you're potentially overfilling the gun by a very significant amount.

The Wika gauges on the 100 are good quality and generally pretty accurate IME; obviously no idea about your bottle gauge but as a rule these tend to be pretty decent too.

For the time being I'd be reducing the pressure in the gun so that it reads sub-200 on both gauges, and looking for another gauge / gauges to use to verify the readings your getting on your current ones. Do you have access to other filling gear and / or guns with gauges?
Click to expand...
My mate has an air bottle so I could start with that . I’ll fill to 200 on his gauge then see what my gun says he has the same gun aswell so I can fill his then and see what his reads . If there is a problem with my gauge will it be the gun or just the gauge itself
 
Dave25494 said:
My mate has an air bottle so I could start with that . I’ll fill to 200 on his gauge then see what my gun says he has the same gun aswell so I can fill his then and see what his reads . If there is a problem with my gauge will it be the gun or just the gauge itself
Click to expand...
Good plan, but fill to 150 on both first to give yourself some wiggle room. If they’re both reading 150 then try the next mark on the bottle gauge, then the next, until you hit 200
 
Personally I go by the gauge on the bottle ... I have found cylinder gauges can read maybe +/- 10 bar depending on the rifle. But then I only ever fill my rifles to 170/180 bar, except for early Daystates and suchlike that like about 150 bar.
Cheers, Phil :)
 
Phil Russell said:
Personally I go by the gauge on the bottle ... I have found cylinder gauges can read maybe +/- 10 bar depending on the rifle. But then I only ever fill my rifles to 170/180 bar, except for early Daystates and suchlike that like about 150 bar.
Cheers, Phil :)
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I always thought 200 bar was the go to point do you find your guns run better at that level or do you do it for safer pressure reasons ?
 
Duff Beer said:
Good plan, but fill to 150 on both first to give yourself some wiggle room. If they’re both reading 150 then try the next mark on the bottle gauge, then the next, until you hit 200
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If it goes out of reading over 150 for example and the gauges then start to not be the same what’s my best solution to find the fix ? To be honest my gun hasn’t ever had a problem after each fill but I don’t know if Iam causing slow damage
 
Dave25494 said:
If it goes out of reading over 150 for example and the gauges then start to not be the same what’s my best solution to find the fix ? To be honest my gun hasn’t ever had a problem after each fill but I don’t know if Iam causing slow damage
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If you fill on your gun to 140bar (or nearest marker) on your bottle, then drop some air and fill to the same pressure on your friends bottle you’ll see which of the three is out. I’d expect the bottles to be very close and it’s the gun that’s out

As far as long term damage goes, I have a feeling the HW100 cylinders would have a seal failure on over pressurisation which will probably be quite exciting but not catastrophic. However, as with all things HPA the aim is to not find those limits, have any drama, or have any injury!

You can also do a ‘back if an envelope’ calculation for how much air is in the gun if it’s showing at 200bar by shooting until it gets to 100bar. If the amount of shots you get is drastically different to what Weihrauch expect then you’ve probably overfilled. As an example, they reckon my .177 full length is good for 126 shots, but I get 134 after it’s been tuned and running around 10.6fpe. If I was getting significantly more than that I’d be concerned something’s not right
 
Dave25494 said:
My mate has an air bottle so I could start with that . I’ll fill to 200 on his gauge then see what my gun says he has the same gun aswell so I can fill his then and see what his reads . If there is a problem with my gauge will it be the gun or just the gauge itself
Click to expand...
Sounds like a plan. If the gauge on the gun is faulty it can be replaced, however the process isn't a whole lot of fun..
 
Dave25494 said:
I always thought 200 bar was the go to point do you find your guns run better at that level or do you do it for safer pressure reasons ?
Click to expand...
For unregulated guns the maximum fill pressure can be above the ideal pressure for shooting, as your HW100 is regulated you will be fine filling to 200 bar.
 
Worry not. Using a friends bottle, you can check bottle gauge against his gun and yours, and also your filling device against his gun and yours.. The problem will move with the wrong gauge and 3 out of 4 should closely agree. Having found the error, you will also know how far out that gauge is, and can compensate. Just do it again after a month or so and check for the same results.
I just had 3 thermostats delivered. 2 have set point 1 degree low, and one is 4 degrees high compared to 2 external thermometers that agree. Once you know an error, it's no real problem. Better than taking guns apart.
 
colinb said:
Worry not. Using a friends bottle, you can check bottle gauge against his gun and yours, and also your filling device against his gun and yours.. The problem will move with the wrong gauge and 3 out of 4 should closely agree. Having found the error, you will also know how far out that gauge is, and can compensate. Just do it again after a month or so and check for the same results.
I just had 3 thermostats delivered. 2 have set point 1 degree low, and one is 4 degrees high compared to 2 external thermometers that agree. Once you know an error, it's no real problem. Better than taking guns apart.
Click to expand...
Would you change the gauge on the faulty one or just know that when the correct one hits required pressure it’s correct and leave the other gauge just reading whatever it reads ?
 
Totally agree with the idea of checking using other bottles, until then don't assume the fault is with the gun gauge. I have seen as many duff bottle gauges as faulty gun gauges. When in any doubt always go with the highest reading.

Once you know which is correct, or which is less incorrect you don't need to replace anything if you don't want to, just make allowances - it's up to you.
 
Dave25494 said:
Would you change the gauge on the faulty one or just know that when the correct one hits required pressure it’s correct and leave the other gauge just reading whatever it reads ?
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I'd leave things alone and trust the one you have cross checked as accurate. You also know what the faulty gauge should be reading so you have another cross check. While filling, it's also not unusual for the receiver gauge to be a couple of bar below the sending gauge because of the pressure needed to open the valve. If the valve is "sticky" that could be a little more. In any case, it's sometimes hard to read some gauges to within 5 bar. You have to be careful to be looking directly at the gauge, not at an angle.
Many "calibrations" are done so as to establish an error. You then live with it and allow for it. An adjustment is not required.
 
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