position1
02-10-2009, 03:19 AM
Hi Everyone
I am doing my training and we have just been taught how to vac a system down.
But I have a few general questions about Vacuum pump use.
Is it bad (I am told it is) for my vacuum pump to suck no load (like open pipes).
When I first start to vac down the system (theres not much load on pump) a lot of oil mist comes from the exhaust of the vacuum pump. Is this normal ?
When I vac down a system, I connect the micron (mTorr) gauge between the service port (low side) and the blue manifold hose. But the gauge can be damaged by pressure and must be removed before charging the system ? When I disconnect the gauge a small amount of air is going to be drawn into the system, and again when I reconnect the blue manifold hose. Does this small amount of air matter ? Should I be connecting the Torr Gauge somewhere else to measure the vacuum so I don't have to disconnect before charging ? Should my hoses have better fittings, like some sort of low loss fitting ?
In training we are taught to vac down to below 500 microns (mTorr) for at least 15 minutes. This is easily achieved on the relatively small practice system and we were able to get down to below 50 in some cases. But we were told some compressor oils can boil at below 50 microns and we shouldn't go this low in practical situations. Is this correct ? What do people regularly vac down to and for how long ?
Thanks for your help.
Ben
I am doing my training and we have just been taught how to vac a system down.
But I have a few general questions about Vacuum pump use.
Is it bad (I am told it is) for my vacuum pump to suck no load (like open pipes).
When I first start to vac down the system (theres not much load on pump) a lot of oil mist comes from the exhaust of the vacuum pump. Is this normal ?
When I vac down a system, I connect the micron (mTorr) gauge between the service port (low side) and the blue manifold hose. But the gauge can be damaged by pressure and must be removed before charging the system ? When I disconnect the gauge a small amount of air is going to be drawn into the system, and again when I reconnect the blue manifold hose. Does this small amount of air matter ? Should I be connecting the Torr Gauge somewhere else to measure the vacuum so I don't have to disconnect before charging ? Should my hoses have better fittings, like some sort of low loss fitting ?
In training we are taught to vac down to below 500 microns (mTorr) for at least 15 minutes. This is easily achieved on the relatively small practice system and we were able to get down to below 50 in some cases. But we were told some compressor oils can boil at below 50 microns and we shouldn't go this low in practical situations. Is this correct ? What do people regularly vac down to and for how long ?
Thanks for your help.
Ben