How cool should the air be around a motor ?

[JDarvall]

I'm concerned with the thought of overheating a motor that I want to enclose in order to keep the noise down.

If I stick a thermometer in there how hot is too hot ? :rolleyes:

I know your supposed to run a cooling fan, but the setup I want may not need it. Can add the fan latter if its too hot in there.

[DavidG]

1. How hot is too hot depends on the class of the insulation. Check the label.
2. The air must be a lot cooler than the motor so you get good heat transfer.
3 The following are Motor max temps, not just the case.


<TABLE class=large><TBODY><TR bgColor=#e4e4e4><TD bgColor=#ffffcc rowSpan=2>Temperature Tolerance Class</TD><TD bgColor=#ffffcc colSpan=2>Maximum Operation Temperature Allowed</TD><TD bgColor=#ffffcc>Allowable Temperature Rise at full load
1.0 service factor motor <SUP>1)</SUP>


</TD><TD bgColor=#ffffcc>Allowable
Temperature Rise
1.15 service factor motor <SUP>1)</SUP>


</TD></TR><TR bgColor=#e4e4e4><TD bgColor=#ffffcc><SUP>o</SUP>C</TD><TD bgColor=#ffffcc><SUP>o</SUP>F</TD><TD bgColor=#ffffcc><SUP>o</SUP>C</TD><TD bgColor=#ffffcc><SUP>o</SUP>C</TD></TR><TR><TD width="20%">A</TD><TD width="20%">105</TD><TD width="20%">221</TD><TD width="20%">60</TD><TD width="20%">70</TD></TR><TR><TD>B</TD><TD>130</TD><TD>266</TD><TD>80</TD><TD>90</TD></TR><TR><TD>F</TD><TD>155</TD><TD>311</TD><TD>105</TD><TD>115</TD></TR><TR><TD>H</TD><TD>180</TD><TD>356</TD><TD>125</TD><TD>-</TD></TR></TBODY></TABLE>

[Grumpy John]

I'm concerned with the thought of overheating a motor that I want to enclose in order to keep the noise down.

Maybe you should look into why the motor is so noisy. None of the motors on any equipment in my workshop are so noisy that I feel I must enclose them in a box.

[BobL]

I'm concerned with the thought of overheating a motor that I want to enclose in order to keep the noise down.

If I stick a thermometer in there how hot is too hot ? :rolleyes:

I know your supposed to run a cooling fan, but the setup I want may not need it. Can add the fan latter if its too hot in there.

Jake, You can't really use a thermometer. You should use a thermocouple attached to the motor housing. If it's for a DC it will get too hot - no question about it.

[JDarvall]

Thanks.

I'm out of my depth again. I don't know what a thermocouple is.

I'll have a 5hp motor churning away outside all day long. up around 100db if uncovered. probably someone off.

[BobL]

Thanks.

I'm out of my depth again. I don't know what a thermocouple is.

I'll have a 5hp motor churning away outside all day long. up around 100db if uncovered. probably someone off.

Sorry - it's of a digital thermometer. The thermocouple is a pair of special thin wires twisted together and joined at one end and in contact with what you want to measure the temp of, and the other ends are connected to a multimeter of some kind. I was thinking glass tube thermometer,which would have to be inserted into a metal tube attached to the motor.

BTW 5 HP is about 50c an hour, $4 a day, $100 a month and $1200 a year - expensive huh!

[JDarvall]

Sorry - it's of a digital thermometer. The thermocouple is a pair of special thin wires twisted together and joined at one end and in contact with what you want to measure the temp of, and the other ends are connected to a multimeter of some kind. I was thinking glass tube thermometer,which would have to be inserted into a metal tube attached to the motor.

yeh, I new that. Just testing yo...:rolleyes: (ta)



BTW 5 HP is about 50c an hour, $4 a day, $100 a month and $1200 a year - expensive huh!

Hope your right. I worked it out to be 70c an hour. .. :rolleyes:....But you'll be envious Bob when you see my DE system, once she's set up. Not mucking about this time. :-

[DavidG]

Build the entire DC into a cabinet lined with sound absorbing material.
You will need some ventilation gaps to allow the DC air out the cabinet.
That should create enough air movement to keep the motor cool enough yet still kill enough of the sound to keep the neighbors happy.

[oldiephred]

I agree with Grumpy, there should not be much noise from a motor. You might dampen the sound but you might also find a lot more damage in the near future if you don't adress the cause. IMHO

[JDarvall]

I agree with Grumpy, there should not be much noise from a motor. You might dampen the sound but you might also find a lot more damage in the near future if you don't adress the cause. IMHO

The motors not even here yet....when its installed correctly thats how loud it is....100db.... dampening the noise of these motors is something they have big in depth discusions about. Its not that the motors stuffed, its just a noisey DE.

It won't bother me with it outside. I wear earplugs and I'm a bit deaf in one ear anyway.

Just might as well do a good job the first time at keeping noise down so I don't annoy anyone, whilst ensuring it doesn't overheat. uno.

[zelk]

The motors not even here yet....when its installed correctly thats how loud it is....100db.... dampening the noise of these motors is something they have big in depth discusions about. Its not that the motors stuffed, its just a noisey DE.

It won't bother me with it outside. I wear earplugs and I'm a bit deaf in one ear anyway.

Just might as well do a good job the first time at keeping noise down so I don't annoy anyone, whilst ensuring it doesn't overheat. uno.

You should consider what I did with a noisy dusty. Build a box around it as someone else suggested, it's bluddy ugly anyway!
http://www.woodworkforums.com/showthread.php?t=46103
Zelk

[JDarvall]

ta Zelk. Had a look at what you've done. looks good.

I was thinking of making two independent walls. Each wall made of 2 sheets of gyprock, sandwiching regular insulation and sitting on rubber. Tried to draw it in the picture there.

Got the idea from reading this...
http://www.record-producer.com/learn.cfm?a=220

I'd really like to be able to drop the noise incredibly. uno....like to say 60db. Its probably not realistic, but I'd get a buzz out of pulling it off using regular materials.

[woodcutta]

Jake,

I think the noise will be the DE fan and not the motor

Regards
woodcutta

[JDarvall]

yes, but in anycase I'll have to enclose the motor as well to keep the sound down. And it'll be outside under corro iron. that why I was concerned about heat build up.

[JDarvall]

sorry, I may be confusing.

Here's basically the DE setup I'm getting. And this is what this is blokes done to try and control noise.
http://www.gallery2.clearvuecyclones.com/v/CV1800+and+CVMax/My-shed-cyclone/
He's built a walk in enclosure of sorts outside his shop.

And I was just playing with ideas that maynot include good ventilation.

[hughie]

apricotripper

At a 100db I would say that your motor has a problem. Bearings, alignment etc. Check these out thoroughly first, 5hp should not produce that sort of noise level. What is it exactly driving? What sort of base is it attached too?

As too noise levels and sound proofing etc. Make sure your mounting and motor are not mechanically bonded or fixed to the wall of the workshop. Otherwise theres resonance problems. Sit it on a decent chunk of concrete or some solid base, you can make the wall out of 100-150mm hollow blocks just stacked up. If your worried about the wall falling down run silicone sealer along the mortar joins. This will allow to you remove or modify it at any time and save money on bricklaying. Ordinary house bricks will do also as well. Using bricks you can leave small gaps at the end of each brick to allow air to pass, especially top and bottom. As to size, give it plenty of height. ie 2-3 times the length of the motor for height. Make sure your box doesn't touch the motor or shed wall.

The trick with sound insulation is make sure to minimise all mechanical bonding between the sound producer and surrounding structures, where possible.

Roofing, stay away from tin/colour bond etc unless you run insulation under it, such as anticon fibre glass blanket stuff.Water proof ply, such as form ply with silicone at strategic places and hold the whole lot down with bricks.


I have used this method to insulate a couple of large vane compressors. We got it down to around 65db. Which is lower than most outside aircon units.Its very cost effective.

[zelk]

Jake,
if you make an DE enclosure you will not have to worry about motor temperature issues, as the air escaping from the filter will circulate around the motor and to some degree, cool it. I believe you may have an inbuilt motor fan anyway.

Regardless of how you construct the enclosure, you will reduce the noise levels. Attention to wall thickness, door sealing and vent design will determine how effective the enclosure reduces the noise. I used MDF for my enclosure, however I designed it in such a way that if I wasn't happy with the initial results, I could take it further with expensive sound dampening or reflecting materials or double up on the wall thickness. As someone said there is motor noise and air flow noise.

Keep in mind, noise also travels up or along the ducting and exits at the machine used, I was quite surprise how much this noise was dampened by inserting a bit of carpet in the duct just before the machine, as shown in my thread.
Zelk

[JDarvall]

ta. thanks for the ideas.

[NeilS]

Jake - not that I fully understand it all, but the frequency range of your DE system is as important as the dB level if you are trying to control how far that noise travels away from your workshop. Low frequency noises travel further than the high frequencies. See attached table.

I knew from taking some dB readings of my 3HP DE system that I was producing more noise at the lower frequencies from the difference between the A and C scale readings, with the C scale readings all higher than the A scale. Like you, I get about 98dB (A) at source.

So I got my son to take some readings with a frequency distribution meter from his work. The results showed most of that noise was generated in the lower frequency range below 400Hz, with peaks at around 40-50 Hz and another around 150-200 Hz. The sub-400Hz sounds produced about 50dB of the overall 98dB. All that low frequency noise is created by the blower blades doing its thing with the air stream. Unfortunately the low frequency noise is harder to insulate against than the higher frequencies.

Now I am really getting out of my depth, but suggest that you look closely at the frequency response, as well as Sound Transmission Class (STC) rating, of any acoustic insulation material you use. Heavy stuff such as brick (see Hughies' post) and earth mounds (that's what they use along freeways in residential areas) is good, 'resilient channel' will help with plasterboard, as will 'green glue' (but any flexible glue is better than rigid) between two or three plasterboard sheets, plus the usual insulation wool. And, as others have said, keeping the sound source isolated from anything that will conduct or become a sounding board is important.

I have a copy of the US Dept of Housing's Sound Transmission Guide of various buiding material combinations (STC ratings only, no frequency info) but it is too large (2MB) to post here. But I can email it to anyone who wants it.

Soundman, a member of these fourums, may also be able to give more informed advice on acoustic insulation.

Hope this has been of more help than hindrance. There always seems to be something else to take into account, particualry with DE systems....:).

Neil

[JDarvall]

Hope this has been of more help than hindrance. There always seems to be something else to take into account, particualry with DE systems....:).

Neil

It has been helpful. Thankyou kindly.

I'm finding it hard to make a decision on what to do on this. Whether to bother or not ? And if I do bother to insulate, by how much. That sort of thing.

And I've found all sorts of ways to do through internet searching. Hard to know which is best.

:)