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#1
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Sound proof a generator- any ideas?
I need to soundproof (as much as possible) a gas powered generator in some
sort of box with sound absorption. The generator needs to breathe and exhaust and needs an opening for power cables to exit. Anyone have experience doing this? The generator is 30"L x 24"W x 25"H and is rated at 81DBA at 7 meters. Thanks in advance. Steve |
#2
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Sound proof a generator- any ideas?
We don't have "film industry" budgets. I need to make it myself, it's a 10 K
gas generator that will be installed in the back of a cargo van. "Kurt Albershardt" wrote in message ... MHF wrote: I need to soundproof (as much as possible) a gas powered generator in some sort of box with sound absorption. The generator needs to breathe and exhaust and needs an opening for power cables to exit. Anyone have experience doing this? The generator is 30"L x 24"W x 25"H and is rated at 81DBA at 7 meters. How big (in kVA) is the genset, and how much is it worth? Good sound attenuating enclosures (like those from Matanuska) are not cheap. The film industry pays well for quiet power. |
#3
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Sound proof a generator- any ideas?
MHF wrote:
I need to soundproof (as much as possible) a gas powered generator in some sort of box with sound absorption. The generator needs to breathe and exhaust and needs an opening for power cables to exit. Anyone have experience doing this? The generator is 30"L x 24"W x 25"H and is rated at 81DBA at 7 meters. Thanks in advance. Is it not already in a box? The first key here is to start with a generator designed to be quiet. That means low speed operation and a lot of poles. Then you get a box, and then you get a special muffler system to reduce the noise leakage through the exhaust. It's MUCH easier to get a commercial silenced generator from Honda or Agreko or one of those guys than try to engineer your own. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#4
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Sound proof a generator- any ideas?
MHF wrote:
We don't have "film industry" budgets. I need to make it myself, it's a 10 K gas generator that will be installed in the back of a cargo van. It will cost you FAR more to make it yourself than to buy one designed for the job. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#5
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Sound proof a generator- any ideas?
Scott Dorsey wrote:
The first key here is to start with a generator designed to be quiet. That means low speed operation and a lot of poles. And water-cooled, at least for the engine. There are a number of inexpensive air-cooled 10k units on the market and they are loud. Water jackets for the alternator is getting a little more exotic, but also helps things. It's MUCH easier to get a commercial silenced generator from Honda or Agreko or one of those guys than try to engineer your own. Yes, speaking from (repeated) experience. |
#6
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Sound proof a generator- any ideas?
Kurt Albershardt wrote:
Scott Dorsey wrote: The first key here is to start with a generator designed to be quiet. That means low speed operation and a lot of poles. And water-cooled, at least for the engine. There are a number of inexpensive air-cooled 10k units on the market and they are loud. Water cooling helps a lot because you can get the radiator outside of the noisy area for better cooling while keeping the noisy section sealed up. BUT, have you tried the little 1KVA units from Honda? Air cooled handheld things, but very, very quiet. Quiet enough to speak in a normal voice right next to them. Water jackets for the alternator is getting a little more exotic, but also helps things. Only time I ever saw this was on some large (20KVA or so) rental thing a a music festival in Richmond. I forget who made it but it was quieter than the Agrekos. I remember looking under the hood and thinking it must me a nightmare to work on. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#7
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Sound proof a generator- any ideas?
Kurt Albershardt wrote:
Fuel cells are close to practical for some portable apps already. I've considered one of the 1.2 kVA Ballard units for awhile and if/when they get a decent reformer for LPG it might well end up in my kit. There's an educational discount program and I'm starting to think of some interesting opportunities that might qualify. That would be very interesting. Around here we have a bunch of APUs, basically little turboprop engines driving 400 Hz generators, which are used to power aircraft on the ground. They also get used when folks need 400 Hz power in nearby buildings, rather than dragging a motor-generator set over and hooking them up. They are ungodly noisy if you are in front of them or behind them, but 90' off-axis you can't hear anything at all other than the reflected noise from nearby buildings. And the noise is all above 1KC, really, and most of it above 5 KC, so it shouldn't be too hard to eliminate with baffling. Somebody has to be able to make a quieted generator with this sort of technology. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#8
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Sound proof a generator- any ideas?
Arny Krueger wrote:
Freed of the need to run at exactly 3600 rpm, these machines feature low speed operation. This also about doubles fuel economy in typical use. The new tech generators also have lots of poles (typically 24). You do NOT want a 3600 rpm generator. Most of the low noise generators run at 1800 or 1200 rpm, and use generators with additional poles in order to get 60 Hz at the lower operating speed. The sound difference is incredible. Doing the inverter trick allows you to get away from the need for tight speed regulation to get good frequency regulation on the output, but you can't really run the engines any slower. I've never really looked seriously at the inverter units, though. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#9
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Sound proof a generator- any ideas?
Scott Dorsey wrote: Arny Krueger wrote: Freed of the need to run at exactly 3600 rpm, these machines feature low speed operation. This also about doubles fuel economy in typical use. The new tech generators also have lots of poles (typically 24). You do NOT want a 3600 rpm generator. Most of the low noise generators run at 1800 or 1200 rpm, and use generators with additional poles in order to get 60 Hz at the lower operating speed. The sound difference is incredible. Doing the inverter trick allows you to get away from the need for tight speed regulation to get good frequency regulation on the output, but you can't really run the engines any slower. I've never really looked seriously at the inverter units, though. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." I've started looking at inverters more seriously recently. My brother recently bought a 'Hunting shack' in NH that he currently has to haul in gas for the generator for the fridge and lights. He is semi-willing to bankroll a photo-cell battery bank system for it. Inverters and photocells are a LOT more efficient nowadays than they used to be. --Dale |
#10
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Sound proof a generator- any ideas?
"Scott Dorsey" wrote in message
... Arny Krueger wrote: Freed of the need to run at exactly 3600 rpm, these machines feature low speed operation. This also about doubles fuel economy in typical use. The new tech generators also have lots of poles (typically 24). You do NOT want a 3600 rpm generator. Most of the low noise generators run at 1800 or 1200 rpm, and use generators with additional poles in order to get 60 Hz at the lower operating speed. The sound difference is incredible. Doing the inverter trick allows you to get away from the need for tight speed regulation to get good frequency regulation on the output, but you can't really run the engines any slower. I've never really looked seriously at the inverter units, though. --scott I do work for Miller Electric, made in the USA welding equipment manufacturer. As people switch to their engine driven inverter based welding power sources, essentially a multi-frequency AC/DC generator, they are getting as much as 20% fuel savings compared to older technology. They have several models that weld and generate power at 1200 rpm that are purchased by customers concerned about noise levels. Steve King |
#11
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Sound proof a generator- any ideas?
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#12
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Sound proof a generator- any ideas?
problem is I need 10K in the van, generator must be in the van, no other
options. "Scott Dorsey" wrote in message ... Kurt Albershardt wrote: Scott Dorsey wrote: The first key here is to start with a generator designed to be quiet. That means low speed operation and a lot of poles. And water-cooled, at least for the engine. There are a number of inexpensive air-cooled 10k units on the market and they are loud. Water cooling helps a lot because you can get the radiator outside of the noisy area for better cooling while keeping the noisy section sealed up. BUT, have you tried the little 1KVA units from Honda? Air cooled handheld things, but very, very quiet. Quiet enough to speak in a normal voice right next to them. Water jackets for the alternator is getting a little more exotic, but also helps things. Only time I ever saw this was on some large (20KVA or so) rental thing a a music festival in Richmond. I forget who made it but it was quieter than the Agrekos. I remember looking under the hood and thinking it must me a nightmare to work on. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#13
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Sound proof a generator- any ideas?
In article
. rogers.com, "MHF" wrote: problem is I need 10K in the van, generator must be in the van, no other options. well I guess your ****ed then,asshole. in case anyone is wondering about the outright rudeness of this post it is in response to his beligerance, ignorance, and rudeness when a poster at aapls made a off the cuff remark about the genset being used for coffee machines. george |
#14
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Sound proof a generator- any ideas?
"Dale Farmer" wrote in message ... Scott Dorsey wrote: Arny Krueger wrote: Freed of the need to run at exactly 3600 rpm, these machines feature low speed operation. This also about doubles fuel economy in typical use. The new tech generators also have lots of poles (typically 24). You do NOT want a 3600 rpm generator. Noisy SOBs. They are the ruination of the solitude in what would otherwise be some of my favorite places. In the woods a typical generator carries for 10-20 miles. Most of the low noise generators run at 1800 or 1200 rpm, and use generators with additional poles in order to get 60 Hz at the lower operating speed. The sound difference is incredible. Of course, with the AC/AC converters, generator speed is irrelevant to power line frequency. Engine speed is based on power needs. Admittedly you need some RPMs if you want real power out of a piston engine, but much of the time it doesn't take much. Small generators are typically sized to meet peak needs which are often starting surges from induction motors. That kind of load doesn't last long, so people end up with a 4 KW generator that only needs to pump out a few 100 watts most of the time. Doing the inverter trick allows you to get away from the need for tight speed regulation to get good frequency regulation on the output, but you can't really run the engines any slower. Not for peak power. If you ask for 4 KW from a 4 KW generator it's going to rev up and try to be loud. This AC-AC converter thing could work both ways, enabling engines to really rev if serious power is required. Since the intermediate form of power is DC it also enables some battery-based strategies for handling peak loads. Some high end products claim they will dip into their starting battery if necessary. I've never really looked seriously at the inverter units, though. I hope to never have the need, but I have lost power at home for maybe 12 days in the last two years. Legacy infrastructure sucks. "C'est un Nagra. C'est suisse, et tres, tres precis." I've started looking at inverters more seriously recently. My brother recently bought a 'Hunting shack' in NH that he currently has to haul in gas for the generator for the fridge and lights. He is semi-willing to bankroll a photo-cell battery bank system for it. Inverters and photocells are a LOT more efficient nowadays than they used to be. Some remote entry point cabins in Canadian parks are set up this way. I'm thinking specifically of the Cache Bay entry at Quetico. They run computers, lights and communications including a real-time charge card validation link off solar cells, wet cells, and a generator for back-up. Keeping the generator turned off most of the time is a good thing. |
#15
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Sound proof a generator- any ideas?
"Steve King" wrote in message
news I just heard a report the other day on NPR, while talking about the great NE blackout, that some Canadian areas still distribute high voltage electricity using DC, which, the claim was, is more efficient than AC. True. Insulation and corona losses are serious issues in BIG power lines. DC carries 40% more voltage (gosh, that's nearly twice the power!) for the same peak voltage. Some insulator stacks are like 20 feet long and weigh fractions of a ton. You've got a minimum of 3 (often 6) of these swinging from a line 80 foot+ towers dancing across farmer's fields, over mountains and through suburbs. Solid-state rectifiers and inverters have made all the difference. Back in the old days people tried this trick with mercury vapor tubes and motor-alternator sets with the motors connected in series and the alternators hooked in parallel. Not a pretty picture! |
#16
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Sound proof a generator- any ideas?
MHF wrote:
problem is I need 10K in the van, generator must be in the van, no other options. How far away from the van do you have to be working? If you can keep the van a few hundred feet away from any place where you are working, you might be able to get away with some of the cheaper stuff. Even so it will be loud just because the engines themselves produce a lot of noise if they aren't specifically designed to be quiet. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#17
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Sound proof a generator- any ideas?
Kurt Albershardt wrote: Dale Farmer wrote: I've started looking at inverters more seriously recently. My brother recently bought a 'Hunting shack' in NH that he currently has to haul in gas for the generator for the fridge and lights. He is semi-willing to bankroll a photo-cell battery bank system for it. Inverters and photocells are a LOT more efficient nowadays than they used to be. For a small system like a cabin, it's often more efficient and less expensive to use DC for the whole system. DC fluorescents, LEDs, and DC fans can be very efficient. Sometimes an inverter is useful for auxillary loads but often I find you can dispense with them completely. Yes and no. It's not a question of pure efficiency. The fridge is already there, and it's one of those dorm sized fridges. It's mostly just for keeping milk and stuff, so it isn't burning lots of power. Place is already wired for AC, and I'd like to keep that investment. The newest generation of compact flouiresent lamps are lots less money and I think I'll get better efficiency from a larger inverter than the little inverter that is in each little DC fluorescent lamp. The generator will still be there for charging the battery bank if needed, but much nicer if it doesn't have to be left running all the time you need lights, and left running as they go to sleep so the fridge will still be cold in the morning. First generation is probably just going to be an inverter and battery bank to be charged by the generator. Then genny just has to be run for a couple of hours each day rather than 18 hours or so per day. --Dale |
#18
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Sound proof a generator- any ideas?
Steve King wrote:
I do work for Miller Electric, made in the USA welding equipment manufacturer. As people switch to their engine driven inverter based welding power sources, essentially a multi-frequency AC/DC generator, they are getting as much as 20% fuel savings compared to older technology. They have several models that weld and generate power at 1200 rpm that are purchased by customers concerned about noise levels. I don't really understand the older technology. As I get it, the way the old AC arc welders work is that they are just a single-phase motor that is designed to have a very high impedance, so that the winding impedance limits the total current that can be produced when the thing works into a dead short. Right? It's like using a big resistor to fake a constant-current source? And I know some of the adjustable ones (we have an ancient Lincoln here) have an external ballast inductor with several taps, so you can adjust the total current that can be delivered into a short. This is probably very inefficient since there are a lot of losses in the whole thing. And the DC ones are just the same thing with a big bridge rectifier on the secondary (It's a bunch of mercury vapor cans on the Lincoln), right? So, with the inverter systems, you are doing the current regulation with the electronic stuff and saving all the ballast losses? I've kind of wondered about this. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#19
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Sound proof a generator- any ideas?
MHF wrote:
I need to soundproof (as much as possible) a gas powered generator in some sort of box with sound absorption. The generator needs to breathe and exhaust and needs an opening for power cables to exit. Anyone have experience doing this? The generator is 30"L x 24"W x 25"H and is rated at 81DBA at 7 meters. Well, now you should know from the replies received that you can buy this cheaper than you can build it, especially since you don't know what needs to be done in order to build it. Reality is a tricky thing. -- hank alrich * secret mountain audio recording * music production * sound reinforcement "If laughter is the best medicine let's take a double dose" |
#21
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OT: small cabin system (was: Sound proof a generator- any ideas?)
Dale Farmer wrote:
I've started looking at inverters more seriously recently. My brother recently bought a 'Hunting shack' in NH that he currently has to haul in gas for the generator for the fridge and lights. He is semi-willing to bankroll a photo-cell battery bank system for it. Inverters and photocells are a LOT more efficient nowadays than they used to be. For a small system like a cabin, it's often more efficient and less expensive to use DC for the whole system. DC fluorescents, LEDs, and DC fans can be very efficient. Sometimes an inverter is useful for auxillary loads but often I find you can dispense with them completely. Yes and no. It's not a question of pure efficiency. The fridge is already there, and it's one of those dorm sized fridges. It's mostly just for keeping milk and stuff, so it isn't burning lots of power. Place is already wired for AC, and I'd like to keep that investment. That pretty well settles it, then. I'm using a marine refrigerator in my camper but it costs over 10x what a dorm-style unit from Costco does. The newest generation of compact flouiresent lamps are lots less money and I think I'll get better efficiency from a larger inverter than the little inverter that is in each little DC fluorescent lamp. Probably not, based on my most recent measurements. I'm seeing 120VAC and 277VAC electronic ballasts with around 90% efficiency which you have to factor into the roughly 85% efficiency of most inverters running at 1/3rd load. Run just the fluorescent and you get swamped by the 10-20W idle current on the inverter. Good DC ballasts are running 85-87% efficient end-to-end, but stay away from the cheap ones. Iota sells some that will drive a T8 or other full-sized bulb for $28 (versus $20-22 for a comparable quality electronic 120VAC ballast.) The generator will still be there for charging the battery bank if needed, but much nicer if it doesn't have to be left running all the time you need lights, and left running as they go to sleep so the fridge will still be cold in the morning. First generation is probably just going to be an inverter and battery bank to be charged by the generator. Then genny just has to be run for a couple of hours each day rather than 18 hours or so per day. In that case, and assuming you're going to be using an AC genset, let me recommend the Iota DLS series converters for bulk battery charging of small-medium banks http://www.iotaengineering.com/dls.htm Linear chargers are notoriously ineffective on most gensets and most of the competetive switchers are at least twice the price. Drop me an email if you want more info--I've got dozens of these in service in all sorts of unusual applications. |
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