Stirrup pumps - Moisture traps?

[Antoni]

I'll take the bate here and bight.

Air outside the house has a mostly slowly varying quantity of water vapour in it. It can take only so much water vapour before the vapour condenses into microscopic droplets of water - fog to you and me.

The amount of water vapour that air can hold as a vapour (that is to say as a gas) increases with increasing temperature of the air.

The air inside a house is very similar to the air outside a house because the ventilation deliberately built into the house lets it in, along with the gas-boiler pulling the air that it needs to operate. The amount of water vapour in the air inside the house is not far off the amount outside (unless you use a dehumidifier as I sometimes do).

In the UK it is usually warmer inside the house than outside. If you opened the doors and let fog in would it stay as fog? No, because as the air warms up it is able to cary more water as gas, and the droplets eVAPORate back into gas.

But there's still the same amount of water in the air in the house, if not more because of your breathing.

A digital humitity meter will read out in relative humidity, not the actual degree of water content in the air surrounding it. That's the difference between the amount of water vapour it could hold as against the amount it does hold.

So, for the same air, having come in through open doors and widows or just ordinary ventilation will read a lower relative humidity on the instrument in the house although it contains the same amount of water because .... the air has been warmed up by the time it arrives at the instrument.

With all the violence that the ususpecting air experiences as it is pumped into an airgun, all that ends up mattering is the amount of water in the air, not the 'relative humidity' of the air when it it was at peace and tranquility before it was abducted.

IMHO, best place to use a pump is a cold frosty high pressure day outdoors - or manage the vapour with dryers.

Here endeth this morning's lesson and I hope I haven't f....d it up.

[Monster]

I'll take the bate here and bight.

Air outside the house has a mostly slowly varying quantity of water vapour in it. It can take only so much water vapour before the vapour condenses into microscopic droplets of water - fog to you and me.

The amount of water vapour that air can hold as a vapour (that is to say as a gas) increases with increasing temperature of the air.

The air inside a house is very similar to the air outside a house because the ventilation deliberately built into the house lets it in, along with the gas-boiler pulling the air that it needs to operate. The amount of water vapour in the air inside the house is not far off the amount outside (unless you use a dehumidifier as I sometimes do).

In the UK it is usually warmer inside the house than outside. If you opened the doors and let fog in would it stay as fog? No, because as the air warms up it is able to cary more water as gas, and the droplets eVAPORate back into gas.

But there's still the same amount of water in the air in the house, if not more because of your breathing.

A digital humitity meter will read out in relative humidity, not the actual degree of water content in the air surrounding it. That's the difference between the amount of water vapour it could hold as against the amount it does hold.

So, for the same air, having come in through open doors and widows or just ordinary ventilation will read a lower relative humidity on the instrument in the house although it contains the same amount of water because .... the air has been warmed up by the time it arrives at the instrument.

With all the violence that the ususpecting air experiences as it is pumped into an airgun, all that ends up mattering is the amount of water in the air, not the 'relative humidity' of the air when it it was at peace and tranquility before it was abducted.

IMHO, best place to use a pump is a cold frosty high pressure day outdoors - or manage the vapour with dryers.

Here endeth this morning's lesson and I hope I haven't f....d it up.

I completely agree with your analysis.

In our houses we tend to add moisture to the air in many ways over and above what comes in from outside. We do this by cooking, cleaning, washing and drying clothes . In older houses, without damp proof courses, moisture is also drawn up into the walls where it evaporates to further add moisture to the indoor air.

IMHO, best place to use a pump is a cold frosty high pressure day outdoors - or manage the vapour with dryers.

Yes, I totally agree with this.

[Monster]

In which case I don't understand your exception.

You are saying the same as I did:

"same amount of water in the air in the house, if not more because of your breathing"

I gave only one example there for brevity.

Yes I agree. I must have missed that bit. Apologies.

I will edit my post.

[Steyr]

You can buy a compressor for 200 ??? Probably inc. an enhanced filter too.? That water trap will be MUCH better than any pump can offer and if your sensible, you can top up you tank as well as the guns reservoi.

[harvey_s]

You can buy a compressor for 200 ??? Probably inc. an enhanced filter too.? That water trap will be MUCH better than any pump can offer and if your sensible, you can top up you tank as well as the guns reservoi.

How can it be MUCH better than something that shows no sign of passing any moisture even after years of use?

Answers on a postcard please...

[Antoni]

Please, can anyone explain how the pump dryers actually work?

I don't understand how a large surface area of glass (beads) dries the air but I'm not saying it doesn't (where does the water go?)

I do know from my use of refrigeration-based de-humidifiers that there's a lot of water in air. So much so that sometimes I add the de-humidifier's tank contents to my washing machine runs to soften the water for the sake of the soap function. My point - a lot of water can be pulled out of the air.

In chemistry experiments at school air involved in the experiment was pulled through a U-Tube containing Sodium Hydroxide powder so that it was completely dry, but that method would invite a disaster in an airgunning situation involving aluminium.

How do the airgun and dive bottle dryers work?

[Monster]

Please, can anyone explain how the pump dryers actually work?

I don't understand how a large surface area of glass (beads) dries the air but I'm not saying it doesn't (where does the water go?)

I do know from my use of refrigeration-based de-humidifiers that there's a lot of water in air. So much so that sometimes I add the de-humidifier's tank contents to my washing machine runs to soften the water for the sake of the soap function. My point - a lot of water can be pulled out of the air.

In chemistry experiments at school air involved in the experiment was pulled through a U-Tube containing Sodium Hydroxide powder so that it was completely dry, but that method would invite a disaster in an airgunning situation involving aluminium.

How do the airgun and dive bottle dryers work?

A previous poster did mention a filter comprising glass beads, but it is not clear to me how that would work either.

The Hill Dry-Pac system uses a desiccant material which has to be changed periodically.

[bill57]

I've been using a cheap Chinese pump on two guns for a couple of years and wouldn't be without it. The pump itself is very well madeand I have had no issues with the guns.

[bighit]

Please, can anyone explain how the pump dryers actually work?

I don't understand how a large surface area of glass (beads) dries the air but I'm not saying it doesn't (where does the water go?)

I do know from my use of refrigeration-based de-humidifiers that there's a lot of water in air. So much so that sometimes I add the de-humidifier's tank contents to my washing machine runs to soften the water for the sake of the soap function. My point - a lot of water can be pulled out of the air.

In chemistry experiments at school air involved in the experiment was pulled through a U-Tube containing Sodium Hydroxide powder so that it was completely dry, but that method would invite a disaster in an airgunning situation involving aluminium.

How do the airgun and dive bottle dryers work?

They will use dessicant to dry the air .

I used to service industrial air dryers like this

http://www.atrgroup.co.uk/product/air-drier

They would go down to -40 dew point

They used desiccant to absorb the water that made it past the water trap . One water trap and two oil filters.

The compressor would pass oil and water so the filters caught that .

The grey tubes were full of desiccant to catch the water produced by the heat of the air.

There was two banks and one would dry the air for 6 mins while the other was getting air forced through it to blow the water from the dessicant . After the 6 mins the bank's would change function so the now dried one was then absorbing the water and the other was drying the dessicant .

I don't think that type of dessicant will dry air unless it's being forced through the dessicant .

It may work in a stirrup pump though .


I have a bag of it here that I got in 2013.


More here . We used the activated alumina in the above driers .


http://theworkshopcompressor.com/lea...sed-air-dryer/

[Steyr]

How can it be MUCH better than something that shows no sign of passing any moisture even after years of use?

Answers on a postcard please...

Because its a much smaller filter on a stirrup pump and not everyone want to eat spinach and have a gf called olive and a villian called Bluto.

I have never been a fan of bicycle pumps to fill air cylinfers... I am still not.... and dont intend to be at any poi t in the future.

[harvey_s]

Someone once told me the glass balls present a massive surface area for any remaining water vapour not caught by the in-pump to condense on...

The same person also claimed the dry-packs fitted by Hills were really just a gimmick and that the flow rate of the incoming air meant that the residency time within the desicant was insufficient to make any other than a token reduction in water content...

All of that could be right of wrong...all I know is what works in a practical application.

[harvey_s]

Because its a much smaller filter on a stirrup pump and not everyone want to eat spinach and have a gf called olive and a villian called Bluto.

I have never been a fan of bicycle pumps to fill air cylinfers... I am still not.... and dont intend to be at any poi t in the future.

It's really not hard unless you suffer from dwarfism in which case the handle height might make it a challenge .

[Steyr]

It's really not hard unless you suffer from dwarfism in which case the handle height might make it a challenge .

Or buy a compressor..... which is..... another option and 160 quid is what you need to spend. Plus, if you want to, you can top the dive tank to.

[Antoni]

Thanks to bighit and Monster for the links above on professional and amateur air dryers. Answered a few questions for me. Glass bead dryers still a mystery however.

[Aardvark55]

I'd just like to say thank you for this. I'm just getting back into air gunning and this will help me make some sensible decisions. I would like to add tho .. as I'm new and definitely PCP and intending to get a tank at some point, a pump in covid short term and backups makes only sense at moment. Can I ask what pump with a moisture trap value for money v common sense would be a good starter ? I was considering a Webley but this thread mentioning moisture trap is making me ask rather than jump. Many thanks. Marc