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Thread: Digital Gauges
11-29-2012, 06:14 AM #79
When I started out, I pulled a vacuum through my manifold, watched the needle on the low side, listened to the vacuum pump and thought I was doing things properly.
My evacuation procedure is quite a lot different today, and I'm still not sure I'm doing things correctly.
11-29-2012, 12:42 PM #80Professional Member*
- Join Date
- Sep 2005
- North GA
In a few years... there will be new technology available and what we do today will be old hat.
Personally, I see VRF (variable refrigerant flow) becoming a standard in all but really CHEAP equipment (both residential and commercial... if it is not already in commercial). And as we already know; sloppy cleanliness and vacuum procedures with a mini-split and you will have issues. Just wait until ALL equipment has EEV's rather than TXV's or pistons... 250 microns may be too high... we may be working to 100 microns as a basic standard soon.
We never stop learning in this business... this is what I like about it!GA-HVAC-Tech
Galatians 2:20-21; Colossians 1: 21-22 & 26-27; 3:1-4; Romans Ch's 5-6-7-8
2 Chronicles 7:14
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11-29-2012, 07:32 PM #81
11-29-2012, 09:13 PM #82
11-30-2012, 10:15 AM #83
Do you do it something like this?
1) Valve off middle port on manifold
2) Hook up to a vapor port and purge your hoses then close ball valve at end of both hoses.
3) Hook up to oil ports, check oil pressure.
4) Close hose valves.
5) Hook up to suction and liquid line. Blow high side to low.
6) Close valve on high side hose fitting. Use suction to remove liquid from hoses.
7) Remove hose
Just wondering because I've never seen anyone else check oil pressure. I haven't been putting the oil back in the system but I'm gonna start doing it this way if that's how its done.
11-30-2012, 11:17 AM #84
That's the correct way to do it. If by oil ports you mean outlet of oil pump and suction port so you can calculate the differential and determine the net oil pressure. You will want to find the specs for the type of compressor you have so you know what oil pressure is good and where the point is that the pump needs replacement (or other problem).
Ball valves on hose ends are great as you can control what enters or leaves your hoses. Not necessarily so with valveless hoses or sealquik hose ends.
Think the procedure through everytime as one missed step and you can introduce air, refrigerant or oil into the system if you do it wrong.
That's what I like about this site. I learned that procedure myself by thinking it out but reading posts on hvac-talk is like having a journeyman at your side teaching you! :beer:
11-30-2012, 01:00 PM #85
Tapping the suction service valve for the net oil pressure is not the correct way. It.s crankcase pressure you want"The only real security that a man can have in this world is a reserve of knowledge, experience and ability." Henry Ford
11-30-2012, 01:33 PM #86
Right you are. I should have clarified that.
For the reading to be accurate, take the suction reading on the compressor body. Do this because there is a small pressure drop across the service valve and barrel of the motor, which could affect the readings.
Good catch D√16!
11-30-2012, 02:07 PM #87
11-30-2012, 07:16 PM #88
Actually, when doing a lot of oil service on a piece of equipment, I'll connect my gauges from liquid to suction and allow refrigerant to flow through them for a short time.
This, effectively cleans the inside of the hoses.
The oil came from within the system. I'm putting it back there so that it doesn't wind up all over the floor or the back of my truck.
11-30-2012, 09:53 PM #89
I'm with you on that. Only thing worse than POE everywhere is dye from some system charged with it and not labeled. You can only find out after it's everywhere where it shouldn't be. New customers always get the old gauges to find out if that $@#* is in there. I only put it in if I lose a contract. KIDDING! I never lose a contract.
12-02-2012, 08:57 AM #90
also. lets say you have blow by and your inflating your crankcase. Between the motor barrel area and the crankcase, there is a quarter sized opening which allows oil returning from suction to drain into the crankcase chamber, which is fitted with a pressure actuated check valve. If the crankcase inflates, this check valve closes. So if you tapped your suction service valve and not your crankcase, you would not see this inflation.
I can not seem to get this through my guys heads. I carry taps and swivel t's just for this purpose. I never seen one compressor here which was tapped before I came here. It's a 5 minute deal. Just do it."The only real security that a man can have in this world is a reserve of knowledge, experience and ability." Henry Ford
12-02-2012, 09:00 AM #91
I wish racks would start being fitted with transducers so I can read net oil on all my pumps. I saw a Kroger where they had the lead pumps on freeq drive, and they were monitoring the net oil this way. They would only let the pump down to half spin, since net oil drops off on recips when you spin slower than that."The only real security that a man can have in this world is a reserve of knowledge, experience and ability." Henry Ford