Sawyer Mini Backflushing

[William F]

I've never had to test it out, but wouldn't the size of the syringe be beneficial in terms of using for irrigation of open wounds? Add some iodine product to sterilize the water and then the syringe's size can create some serious force. I thought I read somewhere (maybe here maybe not) that one of the most important factors of preventing infection in open wounds is to irrigate the wound with high force/pressure. Can anyone with more first aid experience/knowledge chime in here as to the effectiveness of this idea? If I'm correct in my claim then I would argue the weight/bulk is worth it.

[Sam Farrington]

Was going to wait till posting on MYOG about a mini pump filter using the Sawyer mini before bringing this up, but the time seems ripe.

Since I still cling to using bottles, Nalgene makes a soft-sided version of its standard wide-mouth quart bottle for cyclists (and it is lighter than the hard sided version). The top that comes with it can be stripped down to just a screw cap with a nipple projecting from the center of the top of the cap. After the bottle is filled with clean water pumped thru the Mini, the nippled cap can be used to connect the bottle via a short length of tube to the Mini outlet in order to backflush by squeezing the bottle. That creates a lot of pressure and a pint or so of water for backflushing, quite a bit more than from a small syringe. So no need to carry a syringe, just the nippled cap and the short length of tube. Regular Nalgene caps remain connected to the bottle for ordinary use. They don't thread perfectly, but well enough.

Haven't tried this yet on the trail, but the parts work and the concept seems OK.
Please share any flaws you see in the design.

Am wedded to the wide mouth bottles because I can carry tea or slurp in them and scrub them out easily when they start to get moldy. Nothing like a good chug of iced tea on a summit.

[Ryan Rourke]

Flushing a wound with iodine to prevent infection would absolutely be better than not doing it. I don't usually carry a bottle of iodine on me though. Personally I don't think the syringe is needed in the field. I am curious; what is everyone's method of filtering with the mini?

[Ryan Rourke]

Samuel, the system you are thinking of using is what I do but with a smart water bottle (see my previous post). It works great for me. The straw that comes with the mini fits so well that it's hard to remove. I don't see any problems with it.

[Sam Farrington]

Ryan,
Thanks for the feedback.

Dale,
Am going back to Colorado this summer. Who's Dave?

[cody yochum]

That's the setup I was picturing in my head.

[Dean F.]

Just FYI-

I keep seeing people saying that larger syringes generate more pressure. This is incorrect. The smaller syringes generate more pressure, but the tradeoff of course is less volume. One thumbpower over a large area is less pressure than one thumbpower over a smaller area.

When I'm unclogging a feeding tube I reach for the tiny tuberculin syringes.

[/pedantic rant]

[William F]

I'm no physicist but doesn't Force = Mass x Acceleration? In that case a bigger syringe most certainly produces more "force". Please correct me if I'm wrong.

I should clarify: the bigger syringe would have to have a bigger nozzle/opening of course.

[John S.]

Pressure is the ratio of force to the area over which that force is distributed.

Does tuberculin and larger volume syringes have same size exit hole? Maybe they do. In first aid I hear to use an 18 gauge needle to get a certain force for cleaning wounds.

[William F]

But are we not confusing pressure and force here?

[Dale Wambaugh]

Pure physics vs practical use here I think.

You need to fill any void with water before you can produce any pressure.

Other than that, you need to be able to get your hands on the thing and push it up against the nipple on the filter to get a good seal. As annoying as it is, 1.2oz isn't going to break the bank. What does that come to in water weight? A mouthful?

I do like the Smartwater idea and out the cap in my kit.

[Jeremy and Angela]

But are we not confusing pressure and force here?

Per Blaise Pascal: "If a vessel full of water, and closed on all sides, has two openings, one a hundred times as large as each other, and if each is supplied with a piston that fits exactly, then a man pushing the small piston will exert a force that will equal that of one hundred men pushing the large piston and will overcome that of ninety-nine men."

Pressure is, as John said, force acting over an area. Thus, PSI (pounds per square inch) represents a pressure value with "pounds" as the force component.

Addendum: for wound irrigation you want the area of the exit nozzle as small as possible in order to generate sufficient force to wash away debris.

[Dean F.]

>>>Pure physics vs practical use here I think.

Yes, but in fact we ARE talking about pressure, for back flushing the filter. Not force.

FORCE is what you are applying to the plunger of the syringe. This is transmitted to the water via the plug at the end of the plunger. A smaller plug means more force per unit area, thus higher PRESSURE.

Ergo, smaller syringes generate higher pressures for a given force applied to the plunger. Likewise, there is a reason that bicycle pumps are long and skinny.

18g needles are used to irrigate because they will give high volumes of flow than e.g. a 27g needle. It has nothing to do with pressure.

Attach the tubing to a pressure transducer on one end and a syringe on the other. Place a standardized weight on the syringe plunger. Try this with both a 10cc and a 60cc syringe. Yes, the 10cc syringe will produce more pressure than the 60cc syringe. I'm not making this up, I swear.

Granted, yes, for practical matters you would want a certain minimal volume of water to back flush with, so there's a sweet spot there somewhere. A 0.5cc tuberculin syringe is not going to be practical for back flushing, no matter how high a pressure it generates.

[William F]

Thanks for the clarification Jeremy and Dean. I was mistaken. I think I'll skip the experiment and take your word for it ;)

[Jeremy and Angela]

18g needles are used to irrigate because they will give high volumes of flow than e.g. a 27g needle. It has nothing to do with pressure.

Isn't this really a trade-off though? E.g. 18g compared to 27g gives you sufficient volume, but go larger (e.g. the Sawyer syringe w/out a tip) and you don't get sufficient force? (At least, that was my limited experience.)

[zorobabel frankenstein]

For those backflushing at home with hard tap water, do you mix the water with vinegar?

[Gary Dunckel]

Yes. Sawyer recommends doing vinegar back-flushes if you have mineral water deposits.

[zorobabel frankenstein]

Thanks Gary!

[Gary Dunckel]

Zoro,I am on well water here at home, and there are lots of minerals in it. So when I do my post-trip backflushing, I use distilled water and vinegar. I don't want to add any more minerals to my filter than necessary. A gallon of distilled water just costs $1.

[Greg Mihalik]

If you have dissolved iron in the water (rust stains in the sinks and toilets), vinegar won't help. Gotta be distilled.

[Tony Wong]

Finally got a mini to replace my 1st generation "black" sawyer inline filter.

Anyone know of what size tubing to use that would connect the syringe to the filter?

Looks like if I just press the tip of the syringe to the output nipple of the filter that it is not a water tight seal.

The gray straw that comes with ut is too smll a diameter to connect to syringe, but fits the output nipple.

I think that I read on Mountain Laurel's website that he was recommending cutting a small section of the straw and softening it up in boiling water then fitting it to the syringe???

Anyone try this or have a recommendation for tubing?

Tony

[Dale Wambaugh]

You can stretch the straw with a smooth object (I used the tip of a small paintbrush handle) enough to get it started on the syringe tip.

If you are going to get other syringes, craft and art supply stores may have ones with tapered tips that could be trimmed to suit and give a better purchase on the tubing:

As it is, the supplied syringe isn't impossible, just a bit clumsy. You have to grip the filter with a couple fingers and the syringe with thumb and forefingers while pushing the plunger with the other hand. Doing that without dribbling down your side is a bit of a dance.

[Jerry Adams]

"Looks like if I just press the tip of the syringe to the output nipple of the filter that it is not a water tight seal"

Are you sure?

I have Squeeze. Syringe doesn't make a real good seal, but if I press syringe against nipple and push, it works just fine.

[Tony Wong]

@ Dale Thanks for the suggestion…stretching out the supplied tubing sounds like a good idea. Will see if I have something like a cone to insert in the tube to do it.

@Jerry I am not sure, as I have not tried to backflush my filter yet- it is new out of the package. Just looking at it, does not seem like it is water tight between the syringe and the output nipple of the filter.

Tony

[Ryan Rourke]

Please correct me if I'm understanding this wrong. An airtight seal is better than not; and a tube that creates an airtight seal from the syringe to the output nipple is better than the syringe strait to the filter(which is not airtight, or very hard to continuously keep an airtight seal); and a syringes output pressure is caused by the forcing of water volume through a smaller hole?? If this holds true than connecting the in-line adapter to a water bottle and forcing water trough the tube to the output nipple would yield the same results no? The amount of water pressure you can force through the airtight tube, and ultimately to back flush, is a finite psi at this point and easily can be achieved with the syringe or by use of squeezing water through the adapter from the bottle (see blue adapter in pic). This can be done on the trail easily, if you use a water bottle in your system, and you can leave the syringe at home.

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