I'm trying to create a vacuum chamber, with a chamber that doesn't have a perfect seal and I can't replace it. Using a small pump, I need to maintain a vacuum of about 20 mmhg, accurate within about 5 mmhg (15 to 25 mmhg) at a given time.
I'd prefer it if I could rig a regulator of some kind to control the power of the pump. The only thing I can think is to create a regulator out of a syringe, rigged to a linear potentiometer that powers the pump, but I'd like some suggestions before I try anything.
>>1196779
This is usually done by using a valve to throttle the pump line or bleeding air or some gas into the chamber or both.
>>1196783
Yeah, but that's pretty energy inefficient. The chamber leaks very slowly, so there's not much of a point to leaving the pump on non-stop.
>>1196779
So fix the fucking seal you mongoloid. Jesus Christ...
>>1196779
Will your pump even get to hard vacuum? Does it even matter to just leave it running? Is it a shit pump with a shit duty-cycle?
>>1196792
It's not something that can be fixed. I'm not explaining the entire setup, because I can't, but some leakage is common with use.
just suck the leakage out with a straw
>>1196795
20 torr is a pretty low to medium vacuum (0.375 psi)
id try a differential pressure sensor like a mpx5000 http://www.ebay.com/itm/Freescale-Semiconductors-Pressure-Sensor-MADE-in-SOUTH-KOREA-/401307928144?var=&hash=item5d6fd10650:m:mvjXjW7XaIgVgqGNeQSibew
and have either a analog circuit to have it kick on and off at your levels or a microcontroller to have more control/logging
>>1196796
it sounds like you are incompetent and someone is unfortunately paying you for the privilege.
>>1196796
>I'm not explaining the entire setup, because I can't,
It's all super secret intellectual property, if he told us where the rubber gasket was broken we would know the project details and beat him to the patent rights.
>>1197229
>it's hard to get spare parts in Iran
>I know, I'll ask the internet how to use five or six different parts to get around replacing one made of a common material that can on some systems even be cut by hand
>>1197229
>Iran
>vacuum centrifuge project
>Can't talk about it
You're enriching uranium and asking 4chan for help?
>>1196779
Try silicone or something op. U really need it to seal
>>1197248
>>1197271
Haha, no I was just joking. Good to see though that you caught my drift. I mean, how could I resist?
I read how Iranians in the US always call themselves Persians since that is associated with cute fluffy cats, whereas with Iran people suspect them of enriching uranium in the garage.
http://www.bbc.com/news/magazine-19751370
>If you say, 'I'm Iranian,' people think you're enriching uranium in your garage!
Sara , Second-generation Iranian
OP mentioned the problem is the seal, not the chamber and the only plausible reason for that is that the seal is rotating. Thus my interpretation.
>>1196779
>OPs secret "science project"
>>1196796
If its a properly designed vacuum vessel, it is leaking cause something is fucked up. Stop being a mong and just fix the damn leak. Get some god damn rtv if you have to. We use it to patch leaks at work sometimes, pulling more vac on fairly large vessels. It really shouldn't be difficult at all. You just suck.
>>1197138
It didn't seem to me like he wanted to do it right so I didnt bother trying... That would be a good setup though.
>>1196779
Have you tried fucking around with altimeters? If you can get one working at your pressures and with arduino you can controll a relay to turn the pump on and off.
Real digital vacuum gauges are not cheap.
Wipe the sealing surface with some clear RTV then let cure overnight. Use chamber. You can peel off old RTV then re-spooge it as many times as you like.