#31
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rubber compounds
On Tue, 27 Feb 2018 16:35:21 -0500, Frank Krygowski wrote:
On 2/27/2018 1:01 PM, Jeff Liebermann wrote: The wet/dry bulb (psychrometer) was invented in the early 19th century. That morphed into the sling psychrometer: https://www.google.com/search?q=sling+psychrometer&tbm=isch which earned me an afternoon at the local police station while they attempted to identify the type of weapon I was swinging around. I'm betting you and I are the only ones here who have used a sling psychrometer. Sorry, but you loose. I think just about everyone in 7th grade Science (IIRC, it was a while ago) in my school did this. I never got arrested for doing it, though. (I can't even remember where my psychrometric chart is now.) Try page E-39 of the 53d edition (1972-73) of the Rubber Bible. |
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#32
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rubber compounds
On Tue, 27 Feb 2018 21:39:18 +0100, Emanuel Berg
wrote: Jeff Liebermann wrote: Capt Nemo probably had one aboard the Nautilus as too much or too little humidity in a closed environment tends to do bad things to men and machines. What humidity is that? If you are living in a closed environment, with no access to recirculated air, the humidity from everyone's breath and sweat tends to accumulate. Eventually, it gets high enough to be seriously uncomfortable (if the CO2 buildup doesn't kill you first). It's like that in any artificial atmosphere environment, such as space capsules, submarines, and well insulated houses. Humidity is a bit part of feeling comfortable: https://en.wikipedia.org/wiki/Thermal_comfort#Relative_humidity Here in the studio/office right now is 18.3C/22% and in the workshop is -3.6C/56%. With a heat fan, I can get that up to ~4.5C tho. Outside is -11C and a heat fan won't help But I don't need data to know that -3.6C is too cold to work with tools, one needs to go inside in between every individual part just a second to get back warm hands. I'm not sure what point you're trying to make here. RH is the ratio of the amount of water in the air divided by the amount of water it could hold. When the temperature drops, the air can hold less and less water. If you lived in a cold Aortic region, the RH is very low making it as dry as a desert. That's also why you can defrost the inside of your automobile windshield by turn on the air conditioner. Air conditioned air is quite dry. Where an accurate psychrometer comes in handy is demonstrating to buyers of elaborate electronic weather stations that their humidity measurements are very slow to change, and rather inaccurate. I tested my analogous German-made hygrometer after a hot shower, but not in the actual shower of course, and it had changed a lot. So how slow is "slow"? I don't have time for an elaborate answer right now. Search for "humidity sensor response time". You'll find that the common capacitance sensor found in home wx stations varies from about 1 minute (for a large change in humidity) to several days for an initial power on (due to lousy air circulation). This article says: https://www.sensorsmag.com/components/choosing-a-humidity-sensor-a-review-three-technologies "The response time for most resistive sensors ranges from 10 to 30 s for a 63% step change." My experience is more like several hours for capacitance sensors. I'll see if I can find the data sheets on some of the sensors in my collection later today. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#33
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rubber compounds
On Tue, 27 Feb 2018 16:35:21 -0500, Frank Krygowski
wrote: On 2/27/2018 1:01 PM, Jeff Liebermann wrote: The wet/dry bulb (psychrometer) was invented in the early 19th century. That morphed into the sling psychrometer: https://www.google.com/search?q=sling+psychrometer&tbm=isch which earned me an afternoon at the local police station while they attempted to identify the type of weapon I was swinging around. I'm betting you and I are the only ones here who have used a sling psychrometer. They're common enough in the skools. The big problem is that they break easily and make a mess. I vaguely recall that there were several in the "lab", all with at least one thermometer broken. So, I built my own and made the mistake of trying it on the skool bus. The driver didn't know what it was, decided it was a weapon of some sort, and called the police, who were waiting when I arrived at skool. I never got arrested for doing it, though. I wasn't arrested, but rather detained for investigation. My father had to leave the factory early to rescue me. I expected dire consequences or worse. However, all he did was chuckle and suggest that I not perform science experiments on the skool bus. (I can't even remember where my psychrometric chart is now.) They're commonly online. I use the programs and apps on my computah and smartphone. The problem with tables is that they don't include the effect of atmospheric pressure. For charts, search for C.F. Marvin tables. https://www.google.com/search?q=c.f.+marvin+relative+humidity+tables There's also calibration: https://www.allaboutcircuits.com/projects/how-to-check-and-calibrate-a-humidity-sensor/ If you graph the humidity, as measured with a psychrometer, versus the indicated humidity from a capacitive sensor, you'll find about 5% hysteresis. In order to get accurate numbers, I sometimes have to compensate for the effect and others. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#34
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rubber compounds
Jeff Liebermann wrote:
It's like that in any artificial atmosphere environment, such as space capsules, submarines, and well insulated houses. OK, then I'm safe as this building is poorly insulated everywhere and in spots not insulated at all. The room where I am right now is the best insulated place. Still I have three power oil radiators yet temperature is only 18.0C/22% with -8C outside. -- underground experts united http://user.it.uu.se/~embe8573 |
#35
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rubber compounds
On Wed, 28 Feb 2018 17:50:00 +0100, Emanuel Berg
wrote: Jeff Liebermann wrote: It's like that in any artificial atmosphere environment, such as space capsules, submarines, and well insulated houses. OK, then I'm safe as this building is poorly insulated everywhere and in spots not insulated at all. Sorry, bad choice of words. Instead of insulated, I should have said ventilated. A really well insulated house should not have any air leaks, where cold air from the outside can leak in, and warm air from the inside leak out. The room where I am right now is the best insulated place. Still I have three power oil radiators yet temperature is only 18.0C/22% with -8C outside. 26C temperature differential between outside and inside. Yeah, that's quite good insulation, depending on how much energy you're putting into heating the room. My house is a "summer vacation home" which leaks badly and is poorly insulated. Air leaks everywhere, no insulation in the floor, ceiling or roof. Typical is 10C differential with the wood burner setup for best efficiency and 20C when I have it running like a blast furnace. I considered improving the insulation and leakage situation, but it's cheaper to just burn more firewood. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#36
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rubber compounds
On 2/28/2018 6:13 PM, Jeff Liebermann wrote:
On Wed, 28 Feb 2018 17:50:00 +0100, Emanuel Berg wrote: Jeff Liebermann wrote: It's like that in any artificial atmosphere environment, such as space capsules, submarines, and well insulated houses. OK, then I'm safe as this building is poorly insulated everywhere and in spots not insulated at all. Sorry, bad choice of words. Instead of insulated, I should have said ventilated. A really well insulated house should not have any air leaks, where cold air from the outside can leak in, and warm air from the inside leak out. The room where I am right now is the best insulated place. Still I have three power oil radiators yet temperature is only 18.0C/22% with -8C outside. 26C temperature differential between outside and inside. Yeah, that's quite good insulation, depending on how much energy you're putting into heating the room. My house is a "summer vacation home" which leaks badly and is poorly insulated. Air leaks everywhere, no insulation in the floor, ceiling or roof. Typical is 10C differential with the wood burner setup for best efficiency and 20C when I have it running like a blast furnace. I considered improving the insulation and leakage situation, but it's cheaper to just burn more firewood. I used the opposite strategy. When we moved into this house, decades ago, I was sure it was inefficient. I immediately invested lots of time and a fair amount of money in sealing against infiltration and adding insulation. I graphed our natural gas usage for years and was very pleased to see the curve descend markedly. About eight years ago, we did a small addition to the house, and switched from the ancient primitive gas furnace to a high efficiency model. Our gas use is now about 1/3 of what it was when we started. I think the weatherproofing was the best investment I could have made. We do have a fireplace, but it too was terribly inefficient, as almost all are. Not long after we moved in I added glass doors, an outside air intake, a blower grate, etc. That changed the fireplace from ineffective to capable of driving us out of the room. The living room can get up to 80 degrees Fahrenheit with a big fire. But we rarely burn wood these days. I'm not fond of slogging outside to carry the stuff in. -- - Frank Krygowski |
#37
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rubber compounds
Jeff Liebermann wrote:
26C temperature differential between outside and inside. Yeah, that's quite good insulation, depending on how much energy you're putting into heating the room. Well, it sure doesn't feel warm and everything I touch is/feels cold. Now its 17.5C/22% with -9C outside. I have two oil filled radiators that are 1500W by the windows, and one 525W under the bed. -- underground experts united http://user.it.uu.se/~embe8573 |
#38
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rubber compounds
On 2/28/2018 5:59 PM, Emanuel Berg wrote:
Jeff Liebermann wrote: 26C temperature differential between outside and inside. Yeah, that's quite good insulation, depending on how much energy you're putting into heating the room. Well, it sure doesn't feel warm and everything I touch is/feels cold. Now its 17.5C/22% with -9C outside. I have two oil filled radiators that are 1500W by the windows, and one 525W under the bed. an electric heater like this? https://www.ebay.com/itm/700W-Portab...YAAOSwYeRZ5bZd That's it? And your building has an OP issued?? -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#39
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rubber compounds
AMuzi wrote:
an electric heater like this? https://www.ebay.com/itm/700W-Portab...YAAOSwYeRZ5bZd Yes. That's it? And your building has an OP issued?? OP = "occupancy permit"? Then no -- underground experts united http://user.it.uu.se/~embe8573 |
#40
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rubber compounds
On Wed, 28 Feb 2018 18:22:40 -0500, Frank Krygowski
wrote: On 2/28/2018 6:13 PM, Jeff Liebermann wrote: On Wed, 28 Feb 2018 17:50:00 +0100, Emanuel Berg wrote: Jeff Liebermann wrote: It's like that in any artificial atmosphere environment, such as space capsules, submarines, and well insulated houses. OK, then I'm safe as this building is poorly insulated everywhere and in spots not insulated at all. Sorry, bad choice of words. Instead of insulated, I should have said ventilated. A really well insulated house should not have any air leaks, where cold air from the outside can leak in, and warm air from the inside leak out. The room where I am right now is the best insulated place. Still I have three power oil radiators yet temperature is only 18.0C/22% with -8C outside. 26C temperature differential between outside and inside. Yeah, that's quite good insulation, depending on how much energy you're putting into heating the room. My house is a "summer vacation home" which leaks badly and is poorly insulated. Air leaks everywhere, no insulation in the floor, ceiling or roof. Typical is 10C differential with the wood burner setup for best efficiency and 20C when I have it running like a blast furnace. I considered improving the insulation and leakage situation, but it's cheaper to just burn more firewood. I used the opposite strategy. When we moved into this house, decades ago, I was sure it was inefficient. I immediately invested lots of time and a fair amount of money in sealing against infiltration and adding insulation. I graphed our natural gas usage for years and was very pleased to see the curve descend markedly. About eight years ago, we did a small addition to the house, and switched from the ancient primitive gas furnace to a high efficiency model. Our gas use is now about 1/3 of what it was when we started. I think the weatherproofing was the best investment I could have made. We do have a fireplace, but it too was terribly inefficient, as almost all are. Not long after we moved in I added glass doors, an outside air intake, a blower grate, etc. That changed the fireplace from ineffective to capable of driving us out of the room. The living room can get up to 80 degrees Fahrenheit with a big fire. But we rarely burn wood these days. I'm not fond of slogging outside to carry the stuff in. Someone once write that a fireplace is a very good source of heat as it warms one twice. Once when you chop the wood for the fireplace and once more when you burn the wood :-) -- Cheers, John B. |
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