Anyone know of any sites online where you can ask a complicated engineering question?

Hell, paste that bad boy in here and we'll give he a go.

yeah you can ask complicated questions here!!!!

you'll probably get moranic answers, but what did you expect?????

I have a small pump system for a project that requires a small manifold. The total volume of the manifold and the tubing is 2.9828 cu inches. Here is my pump specs:

Inflation time < 8s (from 0-200 mmHg in a 100cc tank)
Air flow > 70mL/min
Max pressure > 360mmHg
Leakage max 36mmHg/15sec from 300mmHg at 70cc tank
Pump time - 7sec on / 7sec off


From the pump is a 3/16" x 12" tube (volume = .3311 cubic inches) which attaches to a small cylindrical manifold (1"x3" - volume = 2.3571 cubic inches) that has two air rails (each air rail (1/4" x 3" -volume = .2946 cubic inches). Total volume should be 2.9828 cubic inches.

I was hoping to see if someone could figure out how big of an orifice I would need on each rail for maximum pressure, within the 7 seconds on, 7 seconds off (basically optimal orifice pressure and size where manifold drops stays at a constant positive pressure at the end of the 7 second off phase wherein the 7 seconds on phase starts to pump and build pressure. Any help on this would be appreciated. Thanks.

Post it. It's not real complicated to post a question on this site even it's you think the question is complicated.

six inch

Tard...

Wow....


That made me feel so dumb...

ummm....

uh......

Have you tried asking these folks?

[link to www.engineersedge.com]

Try this site

[link to www.wolframalpha.com]

7 on / 7 off is pretty short cycling....why the short "on" duration?

Well that was pump specs, I can change that via the 555 timer chip specs, so whatever the optimal time for off and on to yielf the best case volume and pressure given an orifice size if fine...

Maybe cleverbot.com, but she is being coy.


Can AC1018748 ask you a complicated engineering question?

I tried to ask you a question and you didn't even answer it!

[link to cleverbot.com]

Thanks. I asked the question over there.

Grasscity. Srsly, half the stoners are geeks.

need a little more to go on...you talking about off the shelf orifice(s) like for a gas manifold in propane pr natural gas heat?....or you gonna drill them yourself

Drill them myself.

do you have access to a machinist drill index?...one with the "A" thru "xyz" plus the "Fractional" sizes?

This is probably more of a physical chemistry question than it is an engineering question. I believe you could answer this utilizing the root mean square speed equation:
urms = (3RT/M)½
v (rms) = sq rt(3 RT/M) = sq rt(3 N k T/M) = sq rt(3 kT/m)
where R = 8.314 gas const = N k
M = N * m
N = Avogadro No. = 6.02*10^23
M = mass of 1 molecule
k = Boltsman const = 1.38*10^-23
m = M/N = 0.032/6.02*10^23 = 5.316*10^-26


*unless your dealing with constant temp orifice size would fall in a range

Last Edited by Thermogenesis on 09/27/2012 07:35 PM

I think I'll bookmark this thread for when i have a question like this.

not at the moment, but yes.

This looks like a unit conversion problem.

What is the orifice size at the air rail?
That may limit you anyway.

Well I know it would be similar to fluid dynamics, I'm just not sure how to approach this. ...plus its been years since I have delved into this. Mostly a systems engineer now. Anyways, I guess it would probably be easier to approach this as a sealed system, with a max pressure of:

360 mmHg

...and calculate orifice size and time duration for total leak down. Though I'm really not sure which equations to use... however, the system is not closed but dynamic, but at least it may get me in the ballpark...

The air rails are 1/4" ID. and are open, no orifice as of yet. That is basically what I am trying to find out. What orifice size do I need to optimize pressure, and flow, given the pump specs and total system volume...

Sure.

:docbrown:

Sorry, I meant 1-60, 60 being the smallest....
do you have several "blanks" for experimentation?

if so I'd start at #46 which is .081 and work back toward #1 getting bigger as you go.

Inflation time < 8s (from 0-3.86735494 psi in a 6.10237441 cubic inch tank)

Air flow > 4.27166 cubic inches/min 4.27166 =0.0711943 cubic inches/sec

Max pressure > 6.96123889 psi

Leakage max 0.696123889 psi/15s = 0.04640825926 psi/s @ 4.27166209 cubic inch tank

..for reference

Thanks. I should have converted everything over to SI or Imperial...

You not building a NOS injection system are you?

He said orifice... LOL...

No...