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Hi, I've been tasked with fixing an excessive noise issue from a 4kV transformer enclosure and looking into adding a limp wall layer to the inside of the enclosure to absorb airborn noise. The existing enclosure walls are .11" thk steel and about 6" from the transformer. The transformer is on...

ScottyUK: Thanks for the help. I appreciate the input.

Hi I have a general question aout NEMA GPO-3. Is this just a general spec. for flame retardency, track resistance etc or does 'GPO-3' specify certain materials to be used? Eg. I know it's glass/polyester but is that written into the spec or could otyher plastics be used? I guess i'm just trying...

I'm making prototypes in the mold and can't wait weeks for a replacement, I need to make this one functional. FYI UHMW is machinable, about as slippery as teflon and one of the cheapest plastics out there (1/4 the cost of aluminum(?)). So..it seems a flame is all that's left to try (or...

OK heat gun failed. On max temp it was putting way too much heat into the (sample) material and warping it before I could get the surface to melt. Melted surfave was nice and shiny tho..

Yup there's draft. I guess I'll experiment with a heat gun on some samples..

The mold's built up from 2" sheets and it's not split so not much access to internal surfaces (see attached). I managed to get a nice shine on a small test area using 600 thru 1500 wet sanding then coarse and fine acrylic 'scratch remover' polishes followed by red rouge on a drimmel tool. Lots...

I've read that it's very easy to 'oxidize the surface' by going 5 deg C over the temp needed to melt the surface. Do you know if this is correct and if an oxidized surface can be restored? Thanks.

Hi, Can anyone recommend a polish/technique to get a very smooth surface on a UHMW? Ideally something easily obtainable and not requiring a particular skill. The part is a mold and I'm hoping a smoother surface will improve release of shore A 40 silicone parts. Currently the surface has...

Hi, Can anyone recommend a polish/technique to get a very smooth surface on a UHMW? Ideally something easily obtainable and not requiring a particular skill. The part is a mold and I'm hoping a smoother surface will improve release of shore A 40 silicone parts. Currently the surface has...

Hi, I'm trying to analyze the attached part in AutoDesk Inventor (2008) and cant decide upon the best way to constrain it. It's a clamp that gets screwed to a surface and then applies a force towards that surface via a screw. I'm applying a force to the red surface in the pic, but how to...

What are the advantages if any of nickel plating a cold plate? The application I'm considering is an approx 500mm sq 6061 alu plate, 55mm thk cooled by heat pipes. Loads are 500-1000W devices, 140x150mm, 9 per side so about 3/4 of the surface is used.. I've seen (vendor) claims that nickel...

Is the amp draw of a given fan consistently proportional to the CFM being moved? If I map amp draw vs CFM through a range of back pressures in the lab, can I then use that data to determine CFM in real-world applications by measuring amp draw? (using same fan of course) Is this a commonly...

Hi I'm tasked with building a fairly large (48x31x70") vacuum chamber and I'm not sure how to regulate the pressure. I've seen vac regulators that mount inline between the pump and chamber but I'd prefer a regulator that I can mount through the chamber wall, letting air in to maintain the...

Well the temp of each component is monitored so I know where the additional cooling is needed. Problem is the enclosure is absolutely packed with components and the air already has to take a very tortuous route. I want to remove unnecessary restrictions and maximize flow and then have a way to...

OK so I may as well forget pressure/CFM curve and just measure CFM entering or leaving the unit. Does that sound like the best approach and would a velocity grid be the best tool for that? I guess I should say I'm trying to improve the airflow (cooling)through some complex equipment and I'm...

IRstuff, care to explain that post?

IRstuff: You must measure the fan pressure and use its fan curve to determine whether there's anything to be done to improve things, i.e., if your fan is already operating at its capacity, changing the ports will make little difference. Well I'm suspicious that the restriction of the ports...

chicopee:when you install your manometer between the equipment room and plenum be sure that the set up is not influence by the plenum ports, so stay clear for about a couple of feet. I don't have 2 feet of space unfortunately, that plenum is 8" high. When you say 'influenced by plenum ports', do...

My problem is there are a lot of obstructions to airflow close to the blower (which actually pulls air from the unit) and I need to know the pressure drop across the fan to use it's CFM/pressure drop curve. I'm concerned that measuring from the far side of the obstructions would show a falsely...