View Full Version : Thoughts on pump technology...

David S.
05-28-2003, 00:18
I was reading through some of the water filter threads and mulling over the various concerns dealing with pumping vs. gravity, vs. siphon. I personaly own a Pure Hiker and have enjoyed it very much. It does seem like the same thing could be accomplished with less weight....or if not less weight then with less effort.

I started thinking about how my self inflating sleeping pad basicly pumps itself full of air in a single "stroke". Is it concievable that you could have an accordian shaped Nalgene (like the bending part of a drinking straw) that wants to stay expanded but could...with a bit of force, be pushed down and as it expands, suck water into itself through a filtering mechanism. Ideally you would be able to walk away while it expanded and sucked itself full of water. Then of course the "accordian or whatever" pump would double as a water container. Some sort of purge valve would probably have to be incorporated to purge any air pockets in order to top it off. As I think about it there would be some potiental problems with air pressure and stuff.

This is just a brain storm. Anyone care to join in? David S.

05-28-2003, 00:42
Sounds like a good idea to me!! It would have to have something inside of it that would expand the bladder. The foam inside of the self inflating mattresses is what causes them to inflate. As the foam expands it forces the outer material to expand also causing the air to be sucked in through the open valve. I would imagine that it would have to expand pretty forcefully to draw water through a filter element! Im not sure what you could use but a manual one could be made possibly by putting a handle on the end of the bladder so you could pull on it to expand the bladder and draw in the water.Not as conveinent as the self inflating idea but you could prolly draw alot of water with less effort than a regular pump.It would also require a valve with a gasket in order to release air without releasing water to compress and expand it more than once to fill it. Well thats my 2 Pesos (sp?) Streamweaver

05-28-2003, 09:21
To set it up for non-attended operation you'd need to do 1 of two things, weight the end of the accordion bladder to cause it to open. This could be done with a rock in a sack or some other piece of kit. Or you would need a spring inside the bottle/bladder with sufficient force. Both ideas assume a container that is of rigid but compactible construction. This will increase the mass of the container somewhat. A spring to force the container open will also require additional mass both for the spring and material to contain the spring, fix it in place and protect it from corrosion. So your container is going to gain some weight.

The big question is whether the mass required for a container of such construction will be the same or more than the mass required for the pump.

Another secondary concern is that such a container will, by necessity be of a corrugated or spiralling construction providing lots of nooks and crannies for bacterial and algal and fungal growth in the bottle. This creates a cleaning concern not present in smooth bodied containers.

So do the benefits outweigh the complications?