20-02-2011, 13:55
Science Fun Facts
January 5 2009 at 10:29 AM Kristin (Login kd006)
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Some interesting observations from the lab (kitchen):
I bought a used Brava system a while ago, haven’t used it much because of all the time it requires. LOL read the manual, not me. So today I dug out the manual and to my surprise they actually publish their vacuum settings! All this time I thought it was a big secret, but right there in black and white the manual it says 33 mm Hg and on another loose page listed the vacuum as 30 mm Hg, and a low restart at 15 mmHg. So what does all this mean?
I have been following along here with people using the Brava and other domes with airlocks and just sucking out the air, so I got to wondering just how much vacuum that was. Searched the internet for an hour trying to find anything about the human lung capacity for pressure and vacuum with little success. So what else is a mad scientist to do but conduct some experiments! First problem I had 2 foot of tubing, at 30mm Hg = 17.7” of water column I had already found out earlier that the Brava sports box sucked that much (yup sucked water out of the cup and spit it out the vents). So I searched and found some more tubing, added another 4 foot just to be sure. Ok so fill up the Pyrex measuring cup full of water, string the tube through a stainless steel funnel to keep it submerged and connect the sports box. Turned it on holding it at eye level and it ran a bit and it shut off. Tried a couple more times to get an accurate reading and came up with about 27 inches water column which equals 50.4 mm Hg. So apparently the calibration on these things is not what it’s cracked up to be especially at their several hundred dollar cost.
Next was the suck test, same 6 foot of tubing, I could almost draw the water up to my mouth (guessing 54 inches) taking a second harder suck I was able to get it all the way about 60 inches/112mm Hg. Now I have to laugh because in my searching I did come across an experiment for kids to use 50 foot of hose in a stair well and measure how far they could suck water and soda up the tube, since I live in a one floor house and it was dark and cold and I had no intention of climbing on the roof I am really not sure what is possible. I did however find a gauge from a blood pressure cuff I had about and blowing into that only managed about 130mm Hg/69.7 inches water column.
So on to breast pumps, again I had had a disappointing experience buying one used, although it came with two battery powered pump heads neither one seemed to be really working as far as sucking goes. My investigation today revealed that the really good ones have a vacuum of 50 to 275mm Hg vacuum that is adjustable and about 40-60 sucks per min seems standard. So I just scored an Ameda Egnell 50 SMB hospital grade pump off of eBay for $200 with free delivery! It should be a lot quieter than a bosom beauty and all the other cheap eBay pumps that cost twice as much. It actually looks and is a quality piece of lab equipment, cast aluminum base, quality motor and one heck of a big slow moving piston pump, all topped off with a Lexan cover.
I also ordered up a couple of stepper motor driven pumps with controller boards that can interface to a computer for experimentation, range in those is probably 50-150mm Hg. Might be interesting to see where that leads to some even slower pumping cycles and hold times if I can figure out the interface and write a control program.
Just for fun, let’s look at the real forces using a basic model in this case my Brava domes, they are about 4 inch across and 5 inch high just to round off for the curved edges, so each is 20 sq. inches or .14 sq. foot in area. Apply 100mm Hg to that and it equals 279 pounds per sq. foot or 39 pounds of pull on each breast; at 250mm Hg it would be 97.5 pounds of pull. No wonder with some of the smaller round domes it gets so uncomfortable, that is equal to pressing inward that hard.
Isn’t science wonderful?
Kristin
Author Reply
waxingmoon
(Login waxingmoon)
SENIOR MEMBER Re: Science Fun Facts January 5 2009, 3:26 PM
Hi Kristin,
Way to go you mad scientist you... lol. I know that the scientific studies on Brava were always touting low suction pressure. So if I get your right you are saying that the Brava was pulling 50mm Hg versus the maximum of 30mm Hg that is advised.
On the Noogleberry forum, one of the users has a pump that has a brass trigger vacuum pump with a gauge to control the pressure. He states that he uses 15 - 30mm Hg. He also uses enormous domes - what are the original XL Noogleberry cups (now called the XXL). I haven't seen them but supposedly they are like dinner plates at the base. His results are phenomenal and he says that suction is the only method he uses.
I await with interest any further results of your diabolical experiments... lol.
Best wishes,
waxingmoon
Edit Message Delete Message
molehills
(no login) Re: Science Fun Facts January 6 2009, 2:32 AM
hi Kristin, good work! I have an Ameda Elite hospital grade pump, and I want to try getting some bb domes and using it. But it occurs to me that there needs to be some kind of in-line filter to prevent moisture/oil etc getting into the pump. It's a closed system, not the kind of pump you could open up and clean inside as far as I know. Any ideas? Have looked around the web a little but don't see anything suitable. I guess it might be possible to use the milk collection unit (Hygienikit) which has a filter but then there's the further problem of how to attach tubing to it from the domes(maybe via the breast flange somehow). A disposable in-line filter that could take the required pressure seems simpler. If you have any ideas let me know!!
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Kristen
(Login Kristen10) RE: Science Fun Facts January 6 2009, 4:30 AM
Hi Kristin (great name, btw)
Have you tried this pump yet? Can you connect it with the standard Brava tubing/domes, and wear to bed?
Please keep us in the loop on your experiments...
Edit Message Delete Message
roakie
(Login roakie)
SENIOR MEMBER Re: Science Fun Facts January 6 2009, 6:01 AM
I am not a scientist by any means (nearly flunked biology and chemistry) so I am not totally sure what you are trying to say. I am currently using Brava with the smartbox, and alternatively, some nights with manual suction. Are you saying the Brava smartbox is very weak? Have your experiments found that we, as Brava users, should be able to create far more suction inside the domes manually?
The problem with me is that the Smartbox seems to give me more swelling than manual suction. I have alternated numerous times, and the smartbox retains the suction while the manual suction gets very tights (sticking so hard into my ribs I can barely stand it) and then it loses air very gradually (even with a check valve and two applications of no-sting wipe to create more stickiness to my chest.
I am confused.
Edit Message Delete Message
Kristin
(Login kd006) Re: Science Fun Facts January 6 2009, 8:34 PM
Molehills:
Lots of filters out there, off the top of my head you could get a airline filter and the right adaptors to fit the BB or Brava size tubeing, a small inline gasoline filter like used on lawn equipment or an inline fuel filter from the autoparts store. Probably need to get some tubeing adaptors from small to large to adapt it. When I get the pumps and search out what I need I will try and post some better suggestions or part numbers that will work.
Kristen:
See above, no havent received either of the pumps yet, probably not till next week as I haven't seen anything ship yet.
Roakie:
I can see where the Brava box would provide long term suction, and work better because as you mentioned the domes leak down after a while, I am hopeing the smaller vacuum pumps I ordered with controler board will be able to work like the brava box and cycle on when needed and maintain the vacuum, hopefully at a bit higher level.
Really was just spewing information, I was just overcome with curiosity as to what the vacuum levels were from the Brava box, manual sucking on the tube etc. Would love to hear what the BB box does if someone has a length of aquarium tubing and a stairwell to run a test, just to know what 6 o'clock, 12 o'clock and 9 o'clock pull in inches of water column for comparison.
roakie
(Login roakie)
SENIOR MEMBER Re: Science Fun Facts January 6 2009, 8:46 PM
Oh, well that sounds cool. If the newer pump works and you can get greater suction than the smartbox, please keep us informed. That sounds interesting and something I might want to try!
January 5 2009 at 10:29 AM Kristin (Login kd006)
--------------------------------------------------------------------------------
Some interesting observations from the lab (kitchen):
I bought a used Brava system a while ago, haven’t used it much because of all the time it requires. LOL read the manual, not me. So today I dug out the manual and to my surprise they actually publish their vacuum settings! All this time I thought it was a big secret, but right there in black and white the manual it says 33 mm Hg and on another loose page listed the vacuum as 30 mm Hg, and a low restart at 15 mmHg. So what does all this mean?
I have been following along here with people using the Brava and other domes with airlocks and just sucking out the air, so I got to wondering just how much vacuum that was. Searched the internet for an hour trying to find anything about the human lung capacity for pressure and vacuum with little success. So what else is a mad scientist to do but conduct some experiments! First problem I had 2 foot of tubing, at 30mm Hg = 17.7” of water column I had already found out earlier that the Brava sports box sucked that much (yup sucked water out of the cup and spit it out the vents). So I searched and found some more tubing, added another 4 foot just to be sure. Ok so fill up the Pyrex measuring cup full of water, string the tube through a stainless steel funnel to keep it submerged and connect the sports box. Turned it on holding it at eye level and it ran a bit and it shut off. Tried a couple more times to get an accurate reading and came up with about 27 inches water column which equals 50.4 mm Hg. So apparently the calibration on these things is not what it’s cracked up to be especially at their several hundred dollar cost.
Next was the suck test, same 6 foot of tubing, I could almost draw the water up to my mouth (guessing 54 inches) taking a second harder suck I was able to get it all the way about 60 inches/112mm Hg. Now I have to laugh because in my searching I did come across an experiment for kids to use 50 foot of hose in a stair well and measure how far they could suck water and soda up the tube, since I live in a one floor house and it was dark and cold and I had no intention of climbing on the roof I am really not sure what is possible. I did however find a gauge from a blood pressure cuff I had about and blowing into that only managed about 130mm Hg/69.7 inches water column.
So on to breast pumps, again I had had a disappointing experience buying one used, although it came with two battery powered pump heads neither one seemed to be really working as far as sucking goes. My investigation today revealed that the really good ones have a vacuum of 50 to 275mm Hg vacuum that is adjustable and about 40-60 sucks per min seems standard. So I just scored an Ameda Egnell 50 SMB hospital grade pump off of eBay for $200 with free delivery! It should be a lot quieter than a bosom beauty and all the other cheap eBay pumps that cost twice as much. It actually looks and is a quality piece of lab equipment, cast aluminum base, quality motor and one heck of a big slow moving piston pump, all topped off with a Lexan cover.
I also ordered up a couple of stepper motor driven pumps with controller boards that can interface to a computer for experimentation, range in those is probably 50-150mm Hg. Might be interesting to see where that leads to some even slower pumping cycles and hold times if I can figure out the interface and write a control program.
Just for fun, let’s look at the real forces using a basic model in this case my Brava domes, they are about 4 inch across and 5 inch high just to round off for the curved edges, so each is 20 sq. inches or .14 sq. foot in area. Apply 100mm Hg to that and it equals 279 pounds per sq. foot or 39 pounds of pull on each breast; at 250mm Hg it would be 97.5 pounds of pull. No wonder with some of the smaller round domes it gets so uncomfortable, that is equal to pressing inward that hard.
Isn’t science wonderful?
Kristin
Author Reply
waxingmoon
(Login waxingmoon)
SENIOR MEMBER Re: Science Fun Facts January 5 2009, 3:26 PM
Hi Kristin,
Way to go you mad scientist you... lol. I know that the scientific studies on Brava were always touting low suction pressure. So if I get your right you are saying that the Brava was pulling 50mm Hg versus the maximum of 30mm Hg that is advised.
On the Noogleberry forum, one of the users has a pump that has a brass trigger vacuum pump with a gauge to control the pressure. He states that he uses 15 - 30mm Hg. He also uses enormous domes - what are the original XL Noogleberry cups (now called the XXL). I haven't seen them but supposedly they are like dinner plates at the base. His results are phenomenal and he says that suction is the only method he uses.
I await with interest any further results of your diabolical experiments... lol.
Best wishes,
waxingmoon
Edit Message Delete Message
molehills
(no login) Re: Science Fun Facts January 6 2009, 2:32 AM
hi Kristin, good work! I have an Ameda Elite hospital grade pump, and I want to try getting some bb domes and using it. But it occurs to me that there needs to be some kind of in-line filter to prevent moisture/oil etc getting into the pump. It's a closed system, not the kind of pump you could open up and clean inside as far as I know. Any ideas? Have looked around the web a little but don't see anything suitable. I guess it might be possible to use the milk collection unit (Hygienikit) which has a filter but then there's the further problem of how to attach tubing to it from the domes(maybe via the breast flange somehow). A disposable in-line filter that could take the required pressure seems simpler. If you have any ideas let me know!!
Edit Message Delete Message
Kristen
(Login Kristen10) RE: Science Fun Facts January 6 2009, 4:30 AM
Hi Kristin (great name, btw)
Have you tried this pump yet? Can you connect it with the standard Brava tubing/domes, and wear to bed?
Please keep us in the loop on your experiments...
Edit Message Delete Message
roakie
(Login roakie)
SENIOR MEMBER Re: Science Fun Facts January 6 2009, 6:01 AM
I am not a scientist by any means (nearly flunked biology and chemistry) so I am not totally sure what you are trying to say. I am currently using Brava with the smartbox, and alternatively, some nights with manual suction. Are you saying the Brava smartbox is very weak? Have your experiments found that we, as Brava users, should be able to create far more suction inside the domes manually?
The problem with me is that the Smartbox seems to give me more swelling than manual suction. I have alternated numerous times, and the smartbox retains the suction while the manual suction gets very tights (sticking so hard into my ribs I can barely stand it) and then it loses air very gradually (even with a check valve and two applications of no-sting wipe to create more stickiness to my chest.
I am confused.
Edit Message Delete Message
Kristin
(Login kd006) Re: Science Fun Facts January 6 2009, 8:34 PM
Molehills:
Lots of filters out there, off the top of my head you could get a airline filter and the right adaptors to fit the BB or Brava size tubeing, a small inline gasoline filter like used on lawn equipment or an inline fuel filter from the autoparts store. Probably need to get some tubeing adaptors from small to large to adapt it. When I get the pumps and search out what I need I will try and post some better suggestions or part numbers that will work.
Kristen:
See above, no havent received either of the pumps yet, probably not till next week as I haven't seen anything ship yet.
Roakie:
I can see where the Brava box would provide long term suction, and work better because as you mentioned the domes leak down after a while, I am hopeing the smaller vacuum pumps I ordered with controler board will be able to work like the brava box and cycle on when needed and maintain the vacuum, hopefully at a bit higher level.
Really was just spewing information, I was just overcome with curiosity as to what the vacuum levels were from the Brava box, manual sucking on the tube etc. Would love to hear what the BB box does if someone has a length of aquarium tubing and a stairwell to run a test, just to know what 6 o'clock, 12 o'clock and 9 o'clock pull in inches of water column for comparison.
roakie
(Login roakie)
SENIOR MEMBER Re: Science Fun Facts January 6 2009, 8:46 PM
Oh, well that sounds cool. If the newer pump works and you can get greater suction than the smartbox, please keep us informed. That sounds interesting and something I might want to try!