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#21
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"torque wrench" pump/compressor
On Thu, 11 Oct 2018 09:27:02 -0700 (PDT), Frank Krygowski
wrote: On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote: On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg wrote: Just out of curiosity, is there a "torque wrench" pump or compressor? I.e., you would screw on the presta valve, set the gizmo to e.g. 35psi, engage it, and instead of watching the indicator, automagically at the right level it would stop? Most of the gas stations here use an air station that you can set for your desired pressure and then just plug the hose onto the tire valve - there is a little clamp to hold it there. When the tire is inflated to the specified pressure the inflation stops and a bell rings. Since they aren't manufactured here I had assumed that the rest of the world had them too. My experience from 50+ years ago says not to rely on those things, although I suppose they may be different now. Back then I blew a tire off the rim with one. I suspect the problem was the volume of each pumping stroke. In a large sized car tire, the volume surge with each big stroke would be absorbed and barely raise the pressure. In a low volume bike tire, it caused an explosion. That's my guess anyway. I usually inflate using a manual floor pump with a gage. It's easy enough to stop pumping when the dial reads the desired temperature. - Frank Krygowski When I was talking about the gas station automatic tie filler I wasn't thinking about bicycles. In fact I can't remember ever filling a bicycle tire at a gas station, just pump them up at home and ride :-) But you are right, in a bicycle tire a small volume pumped in raises the pressure substantially. -- Cheers, John B. |
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#22
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"torque wrench" pump/compressor
On Thu, 11 Oct 2018 17:53:05 +0000 (UTC), Theodore Heise
wrote: On Thu, 11 Oct 2018 09:27:02 -0700 (PDT), Frank Krygowski wrote: On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote: On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg wrote: Just out of curiosity, is there a "torque wrench" pump or compressor? I.e., you would screw on the presta valve, set the gizmo to e.g. 35psi, engage it, and instead of watching the indicator, automagically at the right level it would stop? Most of the gas stations here use an air station that you can set for your desired pressure and then just plug the hose onto the tire valve - there is a little clamp to hold it there. When the tire is inflated to the specified pressure the inflation stops and a bell rings. Since they aren't manufactured here I had assumed that the rest of the world had them too. My experience from 50+ years ago says not to rely on those things, although I suppose they may be different now. Back then I blew a tire off the rim with one. I suspect the problem was the volume of each pumping stroke. In a large sized car tire, the volume surge with each big stroke would be absorbed and barely raise the pressure. In a low volume bike tire, it caused an explosion. That's my guess anyway. I usually inflate using a manual floor pump with a gage. It's easy enough to stop pumping when the dial reads the desired temperature. Don't you mean, when the dial reads the desired foot-pounds? More likely pounds per square inch, i.e. psi :-) -- Cheers, John B. |
#23
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"torque wrench" pump/compressor
On Thu, 11 Oct 2018 19:03:06 -0400, Frank Krygowski
wrote: On 10/11/2018 3:30 PM, AMuzi wrote: On 10/11/2018 12:53 PM, Theodore Heise wrote: On Thu, 11 Oct 2018 09:27:02 -0700 (PDT), ** Frank Krygowski wrote: * On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote: On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg wrote: Just out of curiosity, is there a "torque wrench" pump or compressor? I.e., you would screw on the presta valve, set the gizmo to e.g. 35psi, engage it, and instead of watching the indicator, automagically at the right level it would stop? Most of the gas stations here use an air station that you can set for your desired pressure and then just plug the hose onto the tire valve - there is a little clamp to hold it there. When the tire is ** inflated to the specified pressure the inflation stops and a ** bell rings. Since they aren't manufactured here I had assumed that the rest of the world had them too. * My experience from 50+ years ago says not to rely on those * things, although I suppose they may be different now. * Back then I blew a tire off the rim with one. I suspect the * problem was the volume of each pumping stroke. In a large sized * car tire, the volume surge with each big stroke would be * absorbed and barely raise the pressure. In a low volume bike * tire, it caused an explosion. That's my guess anyway. * I usually inflate using a manual floor pump with a gage. It's * easy enough to stop pumping when the dial reads the desired * temperature. Don't you mean, when the dial reads the desired foot-pounds? funny. Pressure is mass/area usually. Except on RBT. No, sorry, it's FORCE per unit area. https://whatis.techtarget.com/definition/pressure https://en.wikipedia.org/wiki/Pressure Mass vs. weight vs. other forces is a big item of confusion for physics and engineering students. Teachers work hard to correct the confusion. But if you compress air it gets hotter so temperature should be taken into consideration :-) -- Cheers, John B. |
#24
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"torque wrench" pump/compressor
On Thu, 11 Oct 2018 15:36:04 -0400, Frank Krygowski
wrote: On 10/11/2018 1:53 PM, Theodore Heise wrote: On Thu, 11 Oct 2018 09:27:02 -0700 (PDT), Frank Krygowski wrote: On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote: On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg wrote: Just out of curiosity, is there a "torque wrench" pump or compressor? I.e., you would screw on the presta valve, set the gizmo to e.g. 35psi, engage it, and instead of watching the indicator, automagically at the right level it would stop? Most of the gas stations here use an air station that you can set for your desired pressure and then just plug the hose onto the tire valve - there is a little clamp to hold it there. When the tire is inflated to the specified pressure the inflation stops and a bell rings. Since they aren't manufactured here I had assumed that the rest of the world had them too. My experience from 50+ years ago says not to rely on those things, although I suppose they may be different now. Back then I blew a tire off the rim with one. I suspect the problem was the volume of each pumping stroke. In a large sized car tire, the volume surge with each big stroke would be absorbed and barely raise the pressure. In a low volume bike tire, it caused an explosion. That's my guess anyway. I usually inflate using a manual floor pump with a gage. It's easy enough to stop pumping when the dial reads the desired temperature. Don't you mean, when the dial reads the desired foot-pounds? Oh geez, my mistake! But: Neither! I stop when it reads the desired PRESSURE! Around here we use psi = pounds per square inch. Weirdly enough, my pump's pressure gauge is also graduated in kg/cm^2. I would have used that as a bad example in my courses, since kg is properly used to measure mass, not force. And pressure is force per unit area. (This indicates that the SI system gets misused as much as the U.S. or Imperial system.) But isn't "pound" a measurement of mass also :-? -- Cheers, John B. |
#25
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"torque wrench" pump/compressor
John B. Slocomb writes:
On Thu, 11 Oct 2018 15:36:04 -0400, Frank Krygowski wrote: On 10/11/2018 1:53 PM, Theodore Heise wrote: On Thu, 11 Oct 2018 09:27:02 -0700 (PDT), Frank Krygowski wrote: On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote: On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg wrote: Just out of curiosity, is there a "torque wrench" pump or compressor? I.e., you would screw on the presta valve, set the gizmo to e.g. 35psi, engage it, and instead of watching the indicator, automagically at the right level it would stop? Most of the gas stations here use an air station that you can set for your desired pressure and then just plug the hose onto the tire valve - there is a little clamp to hold it there. When the tire is inflated to the specified pressure the inflation stops and a bell rings. Since they aren't manufactured here I had assumed that the rest of the world had them too. My experience from 50+ years ago says not to rely on those things, although I suppose they may be different now. Back then I blew a tire off the rim with one. I suspect the problem was the volume of each pumping stroke. In a large sized car tire, the volume surge with each big stroke would be absorbed and barely raise the pressure. In a low volume bike tire, it caused an explosion. That's my guess anyway. I usually inflate using a manual floor pump with a gage. It's easy enough to stop pumping when the dial reads the desired temperature. Don't you mean, when the dial reads the desired foot-pounds? Oh geez, my mistake! But: Neither! I stop when it reads the desired PRESSURE! Around here we use psi = pounds per square inch. Weirdly enough, my pump's pressure gauge is also graduated in kg/cm^2. I would have used that as a bad example in my courses, since kg is properly used to measure mass, not force. And pressure is force per unit area. (This indicates that the SI system gets misused as much as the U.S. or Imperial system.) But isn't "pound" a measurement of mass also :-? When I was in school, years ago, we were quite strictly made to write either lb_f (pound force) or lb_m (pound mass), and to include unit conversions from one to the other using constants g (the nominal force of graivty at the surface of the Earth) and g_c (a unit conversion factor). The conversion is: lb_f = lb_m * g / g_c In English units g = 32.2 ft/s^2 g_c = 32.2 lb_m ft/s^2 lb_f but if you didn't include the conversion, you failed. |
#26
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"torque wrench" pump/compressor
On 10/12/2018 10:18 AM, Radey Shouman wrote:
John B. Slocomb writes: On Thu, 11 Oct 2018 15:36:04 -0400, Frank Krygowski wrote: On 10/11/2018 1:53 PM, Theodore Heise wrote: On Thu, 11 Oct 2018 09:27:02 -0700 (PDT), Frank Krygowski wrote: On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote: On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg wrote: Just out of curiosity, is there a "torque wrench" pump or compressor? I.e., you would screw on the presta valve, set the gizmo to e.g. 35psi, engage it, and instead of watching the indicator, automagically at the right level it would stop? Most of the gas stations here use an air station that you can set for your desired pressure and then just plug the hose onto the tire valve - there is a little clamp to hold it there. When the tire is inflated to the specified pressure the inflation stops and a bell rings. Since they aren't manufactured here I had assumed that the rest of the world had them too. My experience from 50+ years ago says not to rely on those things, although I suppose they may be different now. Back then I blew a tire off the rim with one. I suspect the problem was the volume of each pumping stroke. In a large sized car tire, the volume surge with each big stroke would be absorbed and barely raise the pressure. In a low volume bike tire, it caused an explosion. That's my guess anyway. I usually inflate using a manual floor pump with a gage. It's easy enough to stop pumping when the dial reads the desired temperature. Don't you mean, when the dial reads the desired foot-pounds? Oh geez, my mistake! But: Neither! I stop when it reads the desired PRESSURE! Around here we use psi = pounds per square inch. Weirdly enough, my pump's pressure gauge is also graduated in kg/cm^2. I would have used that as a bad example in my courses, since kg is properly used to measure mass, not force. And pressure is force per unit area. (This indicates that the SI system gets misused as much as the U.S. or Imperial system.) But isn't "pound" a measurement of mass also :-? As I used to explain it to students: Properly speaking, a _force_ is a push or a pull on an object. Properly speaking, _mass_ is a measure of the amount of matter in an object. _Weight_ is a particular force, i.e. the force of gravity on an object. So in a U.S. grocery if you buy 2.2 pounds of cheese, you're buying the amount of cheese upon which the earth's gravity exerts a force of two pounds. It's a roundabout way of specifying the mass you want, but it works as long as you're just talking cheese, etc. In a European country, you'd specify you wanted a kilogram of cheese, which is about 2.2 pounds worth. There, you're directly specifying the amount of cheese you want. That makes it sound like the Europeans are much smarter. But they turn things around and sometimes measure forces in kilograms, or pressure in kg/cm^2 etc. Where it makes a difference is in calculations involving force, mass and acceleration. Or other engineering calculations. If you don't clearly understand whether you're dealing with force or with mass, you get answers that are very, very wrong. When I was in school, years ago, we were quite strictly made to write either lb_f (pound force) or lb_m (pound mass), and to include unit conversions from one to the other using constants g (the nominal force of graivty at the surface of the Earth) and g_c (a unit conversion factor). The conversion is: lb_f = lb_m * g / g_c In English units g = 32.2 ft/s^2 g_c = 32.2 lb_m ft/s^2 lb_f but if you didn't include the conversion, you failed. Exactly! And students who ignored all that got answers that were wrong by a factor of 32.2. As I explained it, g_c ("Gee sub C") is just a conversion factor, in the same way that (12 in / 1 ft) is a conversion factor. If a person diligently showed units in their computations, it was obvious when it was needed. Most conversion factors have no names, and it always seemed weird to me that they gave that conversion factor a name. Thousands of students got endlessly confused between the acceleration of gravity g, which is 32.2 ft/sec^2 and that conversion factor g_c, which is 32.2 (lbm*ft)/(lbf*sec^2) Diligent attention to units on ALL quantities straightens out that confusion. At least, for most students. And BTW, I found that engineers typically pay attention to units like that. To my astonishment, some professors teaching basic physics did not. -- - Frank Krygowski |
#27
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"torque wrench" pump/compressor
John B. Slocomb wrote:
Well, I've mentioned that you might research your questions before asking them and Frank has even given you a list of books that might enlighten you and now Sir has told you flat out that you do sound like a troll. You and a bunch of other guys, [insert your name here] etc, can call me what you want, I'm unaffected because every day tons of people express gratefulness for everything I've done in just a couple of years - with firewood, carpentry, bikes, organization, gardening, home improvement, bricklayer, and so on. However people who ONLY make derogatory remarks I'll killfile as it doesn't please me to interact with this kind of person. And this is my last remark on this topic So if I don't respond to further replies, that doesn't mean I agree, it means it don't find this kind of discussion pleasant/productive -- underground experts united http://user.it.uu.se/~embe8573 |
#28
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"torque wrench" pump/compressor
AMuzi wrote:
As a 10th grade dropout, I understand the limits of an autodidact education. When was the last time you were wrong about a bike issue? I mean a principle matter, not grabbing the 9mm combination spanner instead of the 10. PS. Serious question! DS. -- underground experts united http://user.it.uu.se/~embe8573 |
#29
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"torque wrench" pump/compressor
On Fri, 12 Oct 2018 10:18:06 -0400, Radey Shouman
wrote: John B. Slocomb writes: On Thu, 11 Oct 2018 15:36:04 -0400, Frank Krygowski wrote: On 10/11/2018 1:53 PM, Theodore Heise wrote: On Thu, 11 Oct 2018 09:27:02 -0700 (PDT), Frank Krygowski wrote: On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote: On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg wrote: Just out of curiosity, is there a "torque wrench" pump or compressor? I.e., you would screw on the presta valve, set the gizmo to e.g. 35psi, engage it, and instead of watching the indicator, automagically at the right level it would stop? Most of the gas stations here use an air station that you can set for your desired pressure and then just plug the hose onto the tire valve - there is a little clamp to hold it there. When the tire is inflated to the specified pressure the inflation stops and a bell rings. Since they aren't manufactured here I had assumed that the rest of the world had them too. My experience from 50+ years ago says not to rely on those things, although I suppose they may be different now. Back then I blew a tire off the rim with one. I suspect the problem was the volume of each pumping stroke. In a large sized car tire, the volume surge with each big stroke would be absorbed and barely raise the pressure. In a low volume bike tire, it caused an explosion. That's my guess anyway. I usually inflate using a manual floor pump with a gage. It's easy enough to stop pumping when the dial reads the desired temperature. Don't you mean, when the dial reads the desired foot-pounds? Oh geez, my mistake! But: Neither! I stop when it reads the desired PRESSURE! Around here we use psi = pounds per square inch. Weirdly enough, my pump's pressure gauge is also graduated in kg/cm^2. I would have used that as a bad example in my courses, since kg is properly used to measure mass, not force. And pressure is force per unit area. (This indicates that the SI system gets misused as much as the U.S. or Imperial system.) But isn't "pound" a measurement of mass also :-? When I was in school, years ago, we were quite strictly made to write either lb_f (pound force) or lb_m (pound mass), and to include unit conversions from one to the other using constants g (the nominal force of graivty at the surface of the Earth) and g_c (a unit conversion factor). The conversion is: lb_f = lb_m * g / g_c In English units g = 32.2 ft/s^2 g_c = 32.2 lb_m ft/s^2 lb_f but if you didn't include the conversion, you failed. Question. "Lb_m * g". how can you meaure 1 lb_m without gravety? -- Cheers, John B. |
#30
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"torque wrench" pump/compressor
On Fri, 12 Oct 2018 11:08:06 -0400, Frank Krygowski
wrote: On 10/12/2018 10:18 AM, Radey Shouman wrote: John B. Slocomb writes: On Thu, 11 Oct 2018 15:36:04 -0400, Frank Krygowski wrote: On 10/11/2018 1:53 PM, Theodore Heise wrote: On Thu, 11 Oct 2018 09:27:02 -0700 (PDT), Frank Krygowski wrote: On Thursday, October 11, 2018 at 5:00:33 AM UTC-4, John B. Slocomb wrote: On Thu, 11 Oct 2018 08:54:38 +0200, Emanuel Berg wrote: Just out of curiosity, is there a "torque wrench" pump or compressor? I.e., you would screw on the presta valve, set the gizmo to e.g. 35psi, engage it, and instead of watching the indicator, automagically at the right level it would stop? Most of the gas stations here use an air station that you can set for your desired pressure and then just plug the hose onto the tire valve - there is a little clamp to hold it there. When the tire is inflated to the specified pressure the inflation stops and a bell rings. Since they aren't manufactured here I had assumed that the rest of the world had them too. My experience from 50+ years ago says not to rely on those things, although I suppose they may be different now. Back then I blew a tire off the rim with one. I suspect the problem was the volume of each pumping stroke. In a large sized car tire, the volume surge with each big stroke would be absorbed and barely raise the pressure. In a low volume bike tire, it caused an explosion. That's my guess anyway. I usually inflate using a manual floor pump with a gage. It's easy enough to stop pumping when the dial reads the desired temperature. Don't you mean, when the dial reads the desired foot-pounds? Oh geez, my mistake! But: Neither! I stop when it reads the desired PRESSURE! Around here we use psi = pounds per square inch. Weirdly enough, my pump's pressure gauge is also graduated in kg/cm^2. I would have used that as a bad example in my courses, since kg is properly used to measure mass, not force. And pressure is force per unit area. (This indicates that the SI system gets misused as much as the U.S. or Imperial system.) But isn't "pound" a measurement of mass also :-? As I used to explain it to students: Properly speaking, a _force_ is a push or a pull on an object. Properly speaking, _mass_ is a measure of the amount of matter in an object. _Weight_ is a particular force, i.e. the force of gravity on an object. So in a U.S. grocery if you buy 2.2 pounds of cheese, you're buying the amount of cheese upon which the earth's gravity exerts a force of two pounds. It's a roundabout way of specifying the mass you want, but it works as long as you're just talking cheese, etc. In a European country, you'd specify you wanted a kilogram of cheese, which is about 2.2 pounds worth. There, you're directly specifying the amount of cheese you want. I think I must have been out of school for too long. How is 1 kilogram which equates to approximately2.20462262185 pounds a different measurement than pounds? Aren't they both a measurement of the effect of gravity on a certain amount of stuff? That makes it sound like the Europeans are much smarter. But they turn things around and sometimes measure forces in kilograms, or pressure in kg/cm^2 etc. Where it makes a difference is in calculations involving force, mass and acceleration. Or other engineering calculations. If you don't clearly understand whether you're dealing with force or with mass, you get answers that are very, very wrong. When I was in school, years ago, we were quite strictly made to write either lb_f (pound force) or lb_m (pound mass), and to include unit conversions from one to the other using constants g (the nominal force of graivty at the surface of the Earth) and g_c (a unit conversion factor). The conversion is: lb_f = lb_m * g / g_c In English units g = 32.2 ft/s^2 g_c = 32.2 lb_m ft/s^2 lb_f but if you didn't include the conversion, you failed. Exactly! And students who ignored all that got answers that were wrong by a factor of 32.2. As I explained it, g_c ("Gee sub C") is just a conversion factor, in the same way that (12 in / 1 ft) is a conversion factor. If a person diligently showed units in their computations, it was obvious when it was needed. Most conversion factors have no names, and it always seemed weird to me that they gave that conversion factor a name. Thousands of students got endlessly confused between the acceleration of gravity g, which is 32.2 ft/sec^2 and that conversion factor g_c, which is 32.2 (lbm*ft)/(lbf*sec^2) Diligent attention to units on ALL quantities straightens out that confusion. At least, for most students. And BTW, I found that engineers typically pay attention to units like that. To my astonishment, some professors teaching basic physics did not. -- Cheers, John B. |
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