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  • Users: sciguyjim
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  1. sciguyjim

    Methanol reaction with aluminum

    I saw the following post on another forum and can't explain it... "A word about using methanol around aluminum. Here at work we have high pressure liquid chormatography systems that use methanol as an eluent. We were having problems with the system and it turned out that the methanol was...
  2. sciguyjim

    Anybody have experience designing air filters?

    I'm trying to design a high flow, high efficiency air filter and I have no experience so it's all guesswork. I also have no test equipment to guide me. I'm looking for someone to evaluate my design and let me know if it sounds ok or not. For months I've been doing dozens of web searches but...
  3. sciguyjim

    How to compare different air filter design efficiencies

    Hi all, I need some suggestions, guesses even. I'm thinking about making a custom air filter for my car that I want to flow well, of course, but also have better filtering efficiency than some other filters on the market. I'd like to find a way to compare the airflow through each design, and...
  4. sciguyjim

    I'd like to convert CFM to ft/min

    I'd like to be able to convert a volume CFM value to a linear speed of feet/min. The flow = 575 CFM and the pipe diam is 3". This calculation looks correct, do you agree? pipe area=7.065 in^2 575 CFM = 993600 cubic inches/min length of tube to hold 993600 cu in = 993600 in^3/7.065 in^2 =...
  5. sciguyjim

    Trying to visualize amount of turbulence in airflow

    I was told recently that ribbed tubing can have the effect of decreasing the effective diameter of a tube by as much as 50% due to drag. I'm trying to form a mental image of the amount of turbulence and laminar flow in a tube, and how much the drag could be reduced by smoothing the ID of the...
  6. sciguyjim

    Trying to visualize amount of airflow turbulence and drag in pipe

    I was told recently that ribbed tubing can have the effect of decreasing the effective diameter of a tube by as much as 50% due to drag. If I have a ribbed tube 4" in diam with ribs .25" wide and .25" deep, then is it accurate (even a little) to estimate that the eddies causing...
  7. sciguyjim

    Making "permanent" plastic bubbles

    I know this stuff exists and I've done much net searching but I can't find a name for a water soluble plastic-like polymer that can be used to make relatively strong and permanent bubbles for kids to play with. Maybe someone here knows.
  8. sciguyjim

    More at home oil analysis- Acidity

    I thought I'd ask for opinions on a simple pH measurement method I've tried on some used oil samples. I haven't had any oil show up as acidic so I'm not 100% sure the method works. Acidity (pH) is normally measured in water solutions, but it is also monitored in used oils. Oils have acid...
  9. sciguyjim

    Painting sheet metal

    I have a flat-ish piece of sheet metal of the type used for air vents. It is uniformly gray, no obvious galvanizing coating. I have some Rust Control black enamel paint which "stops rust without a primer." My metal piece is brand new and has no rust. It isn't going to be handled...
  10. sciguyjim

    What solvent is used in silicone oil?

    Now and then I hear about solvents in silicone oil, (for example the kinds used to make car tires black and shiny) and the possible problems when they interact with the rubber. Does anyone know what these solvents are? I wouldn't expect the silicone oil to have much solvent action of its own.
  11. sciguyjim

    Need explanation of heat transfer from metal surface

    Am I correct in assuming that I can get maximum heat transfer from a metal object (through convection and radiation) by having a rough, black, matte surface? I know black radiates best, but I've heard people suggest painting an object black to increase heat radiated (vs shiny silvery surface.)...
  12. sciguyjim

    Geometry question, need outside diameter of 3 grouped objects

    If I have 3 tubes, each 1" diameter grouped together at 120° angles, what would be the diameter of a larger tube which could enclose the 3 smaller tubes? There must be a formula, or 2, to calculate this. Thanks.
  13. sciguyjim

    Want to calc pressure of airflow on a surface

    I want to calculate the back-pressure caused by an airflow hitting a concave surface (high drag) perpendicular to the airflow. I'm starting with airflow in CFM through a tube, a rough measurement of the area impacted in square inches at the end of the tube, and the tube diameter. I did this...
  14. sciguyjim

    How do I attach sacrificial metal to car for rust control?

    This is probably an easy question, & I'm not happy that I can't figure it out myself, but I'm trying to experiment with magnesium as a sacrificial electrode as a means of preventing rust formation on my car. I live in the Chicago area so there is plenty of salt and damp weather in the winter...
  15. sciguyjim

    How much air density benefit from CAI vs warm air under hood

    I've seen several questions recently about whether a restrictive CAI would be better than an open filter sucking in warm air under the hood. Depending on the restrictions, of course, It seems to me that the small % inc in density of cold air vs warm will not be as beneficial as an open filter...
  16. sciguyjim

    Does zinc galvanizing contain other heavy metals?

    I know someone who wants to serve lemonade from a galvanized metal bucket (has to do with a party theme). Since the drink will only be in the bucket a short time it won't have time to dissolve much metal but I wondered what it could dissolve besides zinc? Maybe lead or cadmium?? Thanks.
  17. sciguyjim

    Does zinc galvanizing contain other heavy metals?

    I know someone who wants to serve lemonade from a galvanized metal bucket (has to do with a party theme). Since the drink will only be in the bucket a short time it won't have time to dissolve much metal but I wondered what it could dissolve besides zinc? Maybe lead or cadmium?? Thanks.
  18. sciguyjim

    What is BTU rating of auto air conditioning ?

    Just curious about this. Someone asked this question recently and nobody had a clue. A ballpark figure would be sufficient. Thanks.
  19. sciguyjim

    Estimating airflow turbulence

    Hello, I've been reading about how reducing turbulence in the air intake tubing, MAF sensor, etc. helps increase airspeed into the engine. I was wondering if there is a way to estimate how much improvement (smoothing of the airflow) I can expect if I do something to smooth out the...
  20. sciguyjim

    Modifying Oil Viscosity to Suit Your Needs

    I read somewhere that mixing oils in 2 viscosity ranges to obtain an average viscosity was OK to do as long as they were the same brand (due to differences in additive packages.) Now, 10w40 synthetic oil isn't recommended these days because it has much more viscosity index improver than say...

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