pcp leave fully charged or not

[pistolnut]

i have a Artemis pp700sa pistol, just wandering I normally pump it back up and leave it fully charged on 200 bar, is this wise or should i leave it on 100 bar after a shooting session.

[eyebull]

i have a Artemis pp700sa pistol, just wandering I normally pump it back up and leave it fully charged on 200 bar, is this wise or should i leave it on 100 bar after a shooting session.

As a rule of thumb you should always store PCPs with some pressure in the tank or tube as this is best for the seals. There's no advantage to leaving it under lower pressure. Same applies with bulk fill CO2, but not where 12g powerlet seals are under compression.

[Monster]

There is some advantage to storing PCPs at a lower than maximum pressure. The dew point of air (the temperature where liquid water condenses out of the air) is lower at lower pressures. This means that storing at a lower pressure means it is less likely that the gun will suffer internal corrosion, especially if you use a stirrup hand pump to charge your PCP.

For long term storage, I store my guns at about 100 bar.

[eyebull]

There is some advantage to storing PCPs at a lower than maximum pressure. The dew point of air (the temperature where liquid water condenses out of the air) is lower at lower pressures. This means that storing at a lower pressure means it is less likely that the gun will suffer internal corrosion, especially if you use a stirrup hand pump to charge your PCP.

For long term storage, I store my guns at about 100 bar.

Hmmm. I would disagree on the basis that if you're not using a drypac and letting moisture get into the gun, then you're already onto a loser because the moisture will accumulate regardless, and it's going to get pressurised up to 200bar+ - where it is more likely to condense - when it is in use. Best to address the moisture issue at source.

There may be some advantage if storing for years at a time (even then your best protection is not letting moisture in in the first place), but the OP is talking about between sessions.

[pistolnut]

thanks for your comments ill leave it at 200 bar as it will be used regular,

[Monster]

Hmmm. I would disagree on the basis that if you're not using a Drypac and letting moisture get into the gun, then you're already onto a loser because the moisture will accumulate regardless, and it's going to get pressurised up to 200bar+ - where it is more likely to condense - when it is in use. Best to address the moisture issue at source.

There may be some advantage if storing for years at a time (even then your best protection is not letting moisture in in the first place), but the OP is talking about between sessions.

I agree that, in principle, it is much better to deal with the moisture problem at source. But, having spoken, at some length, to a technical person at Hill, although with a Drypac the moisture content is very much lower than without, it is still pretty borderline and nowhere near as good as the standard required for diving breathing air.

According to Hill the air from a pump fitted with a Drypac has a dew point of around -40C at atmospheric pressure. If you throw that number into a dew point calculator you find that at 100 bar the dew point is nearly +11C. That is quite a bit colder than in my gun locker, so no condensation can form in the gun. However, at 200 bar the dew point is nearly +22C which is a bit warmer than in my house, so liquid water could start to condense inside the gun.

As far as the OP's question is concerned, if filling using a hand pump, or even a home compressor, I would store at ~100 bar and fill the gun to 200 bar just before use if at all possible. If using diving/breathing standard air from a cylinder, I really wouldn't worry about it and store at 200 bar if that is most convenient.

[eyebull]

I agree that, in principle, it is much better to deal with the moisture problem at source. But, having spoken, at some length, to a technical person at Hill, although with a Drypac the moisture content is very much lower than without, it is still pretty borderline and nowhere near as good as the standard required for diving breathing air.

According to Hill the air from a pump fitted with a Drypac has a dew point of around -40C at atmospheric pressure. If you throw that number into a dew point calculator you find that at 100 bar the dew point is nearly +11C. That is quite a bit colder than in my gun locker, so no condensation can form in the gun. However, at 200 bar the dew point is nearly +22C which is a bit warmer than in my house, so liquid water could start to condense inside the gun.

As far as the OP's question is concerned, if filling using a hand pump, or even a home compressor, I would store at ~100 bar and fill the gun to 200 bar just before use if at all possible. If using diving/breathing standard air from a cylinder, I really wouldn't worry about it and store at 200 bar if that is most convenient.

Very interesting. Might it then be a good idea to periodically, say a couple of times a year, vent all air from a cylinder and refill if primarily using a hand pump?

[ratbuster2240]

I've used an FX stage 3 stirrup pump with just an internal moisture trap for 10 years on my s410 TDR. I recently replaced the cylinder and I inspected the cylinder internally and it looked the same as the brand new one. Sometimes I stored it for months fully charged and others at half capacity, it made no difference.

[Monster]

I've used an FX stage 3 stirrup pump with just an internal moisture trap for 10 years on my s410 TDR. I recently replaced the cylinder and I inspected the cylinder internally and it looked the same as the brand new one. Sometimes I stored it for months fully charged and others at half capacity, it made no difference.

And I've seen that this is a lot of people's experience in practice. I can only speculate why this may be the case.

The first thing that springs to mind is that PCP air gun internals may not be particularly prone to corrosion, even in damp conditions. The second is that perhaps people store their guns somewhere warm enough that condensation does not occur.

All I can say is that I was given a Webley Axsor where the previous owner had used a hand pump for a number of years and when I dismantled it, to repair a leak, there was plenty of that lovely green corrosion product on all the brass internal components. Fortunately, they all cleaned up fine with some wire wool and the gun is now good as new.

My background is in engineering, and there is a saying " If it works in the numbers it definitely works. If it doesn't work in the numbers it still might work". The numbers say that the moisture levels that hand pumps deliver are definitely borderline.

[Monster]

Very interesting. Might it then be a good idea to periodically, say a couple of times a year, vent all air from a cylinder and refill if primarily using a hand pump?

Personally, I think that the only real solution is what you said in the beginning, you have to tackle the problem at source.

During the first Covid lockdown I could not get my air cylinder filled so I bought a Hill pump with Drypac. I used that all through lockdown and a bit beyond, filling before use and storing at around 100 bar. I am sure that my guns have come to no harm. However, I have now gone back to filling my guns with breathing standard air from a cylinder filled at my local diving shop. I would still use the Hill pump, but only when I have to, and I would store the gun at 100 bar.

Just to add, I don't think emptying and refilling a gun, using a hand pump, would actually make any difference.

[rapidresponse1]

always stored mine full over the years never had a issue

[harvey_s]

Altaros reckon their regulators are best kept longer term at their minimum pressure.