Gt-12

[gwaii]

I can only imagine the mess involved with all your projects.

i don't know if you could....

you MUST post pics of this... i'm sure i've seen pics of the dual engine setup somewhere on here...


keep in mind atmospheric pressure is about 14.7 PSI, the pump i was testing yesterday was around 0.001 PSI when we shut it off, and we are fairly confident we could get it lower if it stayed running an hour or so

funny...i was thinking about vacuum pumps this morning.nothing so fancy as those,but just something for vacuum molding parts and recovering the dash pad...

and as for the grady,my plan is to run it with a go-pro aimed at the speed display(it's on the gps/chartplotter)so when they pick up the pieces left floating they can see how fast i was going

 

[--weezl--]

Lol nice Tom!

For vacuforming parts, a shopvac should almost be strong enough... You don't so much need a vacuum pump as a vacuum... The one we were playing with was the largest of the 3 sizes we had there at the time, and out of the 150ml of air that it was sucking out of, it took probably 20 minutes to get to that vacuum... It is very low volume once it starts getting down to anything readable by our gauge (1-2000millitorr)


Sent from somewhere naughty!

 

[gwaii]

Lol nice Tom!

For vacuforming parts, a shopvac should almost be strong enough... You don't so much need a vacuum pump as a vacuum... The one we were playing with was the largest of the 3 sizes we had there at the time, and out of the 150ml of air that it was sucking out of, it took probably 20 minutes to get to that vacuum... It is very low volume once it starts getting down to anything readable by our gauge (1-2000millitorr)


Sent from somewhere naughty!

i'm sure i'll end up using a shop vac,but i've found them lacking a little on the smaller pieces.maybe two of them hooked in series.

as for the grady,i'll probably be posting the video on youtube(never used it before)and setting a link on the 'fishing haida gwaii' thread.i'll try to keep most of the boat stuff there.

 

[--weezl--]

two shop vacs in parallel probably won't do anything... it's not a matter of precharging the air, it's just efficency of the motor, there's too much "blow by"

you would probably have better luck using the intake on an air compressor... you could easily rig something up so that you have two air ducts on the vacuchamber, one for high volume, to get it started, then a second to continue pumping air out once the shopvac has reached it's limit... maybe with a couple one way valves?

i realize compressors are designed to compress not to suck, but it SHOULD still work... idk though... maybe a compressor with the motor running backwards?

 

[gwaii]

two shop vacs in parallel probably won't do anything... it's not a matter of precharging the air, it's just efficency of the motor, there's too much "blow by"

you would probably have better luck using the intake on an air compressor... you could easily rig something up so that you have two air ducts on the vacuchamber, one for high volume, to get it started, then a second to continue pumping air out once the shopvac has reached it's limit... maybe with a couple one way valves?

i realize compressors are designed to compress not to suck, but it SHOULD still work... idk though... maybe a compressor with the motor running backwards?

two shop vacs in series,not parallel.that way the first one would drop the pressure in the second one,essentially precharging it.

i don't know if it would actually work to lower overall pressure at the nozzle,but it's easy enough to try.
the inlet from an air compressor could work ok,but the problem is with the way the rings seal.they are forced against the cylinder by pressure,restricting the inlet by using it as a vaccuum source will cause them to draw in so it will pull air from the crankcase.most air compressors don't care which direction they turn,so reversing the motor will make no difference.

 

[--weezl--]

yeah, i know what you mean about the shopvac, that's what i was thinking, still don't think it will work... but no harm in trying of course...

what it's going to come down to, is vacuums don't create a negative pressure, all they do is remove excess air, i realize it sounds like the same thing, but if you were to measure it with a pressure gauge, it wouldn't move much from atmospheric... the excess air that is in the bag that you vacuum will be removed, and the air will conform to the shape, thus giving the appearance of vaccupacking... try this, (if you want of course) take your shop vac, put the hose over your mouth, turn it on and breathe in... your lungs are more powerful than the shop vac is... volume wise, no comparison though

i see what you mean about the compressor...

 

[livetoride21]

wow. No comments for 2 months? Everything alright in the land of Haida Gwaii? Really itching to see some progress.

 

[Robert_1967]

Last I heard (read) was he was setting up his new house, and getting every thing squired away.




Robert





posted with a rooted copy of the "50 shades of grey".

 

[kimcrwbr1]

Maybe one of those matress air pumps will pull it down enough, unless you can get your hands on a vacuum pump for pulling down refrigerant systems
http://www.ebay.com/itm/3-CFM-Singl...753?pt=LH_DefaultDomain_0&hash=item589c2fbac9
We have about four old ones in our shop that would work great for your application. maybe you can find one at a pawn shop or on craigs list if you have that kind of stuff up there.

 

[--weezl--]

Maybe one of those matress air pumps will pull it down enough, unless you can get your hands on a vacuum pump for pulling down refrigerant systems
http://www.ebay.com/itm/3-CFM-Singl...753?pt=LH_DefaultDomain_0&hash=item589c2fbac9
We have about four old ones in our shop that would work great for your application. maybe you can find one at a pawn shop or on craigs list if you have that kind of stuff up there.

those are the pumps i was talking about, they don't pull a high volume, they are designed to pull virtually all air out of an area, but take hours to do the job... to check for leaks on a refrigeration unit the size of which you would find on a normal house fridge, you would leave this pump running for 24 hours to get the pressure down low enough, then you would block it off, and wait another 24, to see if the pressure drops

 

[alwaysFlOoReD]

to see if the pressure rises

^^^ wouldn't this be what you're hoping not to see?

Richard

 

[--weezl--]

yes, precisely, so you create a huge vacuum, then block it off, and let it sit, if the vacuum drops (pressure rises) which brings the sealed unit to closer to atmospheric pressure, you know you have a leak somewhere

 

[kimcrwbr1]

yes, precisely, so you create a huge vacuum, then block it off, and let it sit, if the vacuum drops (pressure rises) which brings the sealed unit to closer to atmospheric pressure, you know you have a leak somewhere

If your talking refrigeration a vacuum test is not necessary you can pressure test with nitrogen at 350 psi for 45 minutes and if it hold pressure pull it into a deep vacuum for about 45 minutes to boil off any moisture and then add the refrigerant. Never leave a refrigeration system in a deep vac without a running pump to evacuate the noncondensables. Water boils off into gasses at around 800 microns when it gets below 500 microns it boils the moisture out of the oil. You can leave the pump running for 24 hours if the system was open for very long to be sure you removed all the water and add the oil first if necessary and add the refrigerant while still in a deep vac. A single drop of water will destroy the compressor with the acid it produces.

 

[--weezl--]

either way, if it's required or not, that's how it is tested by the company i rebuilt the pumps for...

they are obviously used also for creating the vacuum so you can pump in the refrigerant and know there are no contaminants

 

[kimcrwbr1]

The way you check for contaminates in a refrigeration system is with temp. For example if you have a 25 lb can of refrigerant holding 1 lb of refrigerant has the same pressure as one with 25 lbs. measure the pressure of the tank/system and the temp should be the same using the guage set or chart for that type of refrigerant. When adding or removing refrigerant the pressure has to be higher or lower than the charging vessel. The refrigerant will migrate to the low side when you open the valve. It can be difficult removing refrigerant from an overcharged system one trick is to submerge the charge can in ice water to reduce the pressure to receive the refrigerant. The compressor turns the low pressure vapor (superheated refrigerant ) into a high pressure vapor, that goes through the condenser and subcools the refrigerant and turns it into a high pressure liquid. That liquid goes through the expansion device and going from high pressure to low pressure the refrigerant flashes off into a low pressure vapor and goes through the evaporater and absorbs the heat or is superheated and then goes into the compresser and the cycle continues. Your not adding cool to the cab your removing the heat. But the real question here is where are the pics of the GT-12?