While awaiting parts to arrive, I dug out my old Robinair 15400 pump and micron gauge. Both have been in a box for the last 18 years or so. Warmed-up pump and replaced the oil (with Robinair oil). Connected micron gauge and it pulled down to abt 180 microns within a couple of mins. This pump is rated at 15 microns. I think it will be good enough but wanted to see if there was a quick fix or if I need to install a seal kit. I suspect the shaft seal has hardened over the years.
Thoughts?
Improving vac pump perf
-
JohnHere
- Preferred Member
- Posts: 1825
- Joined: Sun May 13, 2018 10:20 am
- Location: South Carolina Upstate - USA
Re: Improving vac pump perf
If your vacuum pump will evacuate the system to about 500 microns, that's all you'll need. Ensure that the vacuum holds.
For an 18-year-old pump that evacuates to 180 microns with an oil change and a direct connection to the micron gauge, that performance is pretty good. Double-check your micron gauge that the sensor is clear of any debris and that it doesn't have any oil in it.
For an 18-year-old pump that evacuates to 180 microns with an oil change and a direct connection to the micron gauge, that performance is pretty good. Double-check your micron gauge that the sensor is clear of any debris and that it doesn't have any oil in it.
Member – MACS (Mobile Air Climate Systems Association)
Thankful for the responses you have received? Please consider making a monetary donation to this Forum.
Thankful for the responses you have received? Please consider making a monetary donation to this Forum.
Re: Improving vac pump perf
After messing with the hose connections, I'm now able to achieve 130 microns in 3 mins and down to 91 microns after abt 20 mins. Holding it is another matter. If I close pump isolation valve, vacuum goes over 500 microns in a few mins with just the micron gauge connected via 3 ft hose. Still not sure if it's moisture boiling off, hose outgassing or something leaking.
-
JohnHere
- Preferred Member
- Posts: 1825
- Joined: Sun May 13, 2018 10:20 am
- Location: South Carolina Upstate - USA
Re: Improving vac pump perf
A reading of ~500 microns, excellent for MVAC systems, is an extremely small, measured amount of vacuum that you can't even notice on a high-quality Manifold Gauge Set's low-side gauge in Inches of Mercury (InHg). That said, temperature, pressure, and material composition can also affect outgassing, and hence, rising micron rates.
When measuring vacuum with a micron gauge, outgassing of the material in an MVAC system—that is, the oil and desiccant (even if new), hoses, seals, and etcetera—plus air and moisture that might be trapped in the system, can affect the reading observed on a micron gauge.
The micron gauge should eventually "settle down" after evacuation to less than, say, 1,000 microns in an MVAC system, unless the system or equipment has a leak. Be aware that a micron-level leak probably can't be detected even by a sensitive electronic "sniffer" unless it's a substantial leak (non-micron-level).
The best you can do is to either change every o-ring, seal, and hose in your vacuum pump setup in an effort to prevent any equipment leakage, or (presuming your setup isn't leaking) continue evacuating until the micron gauge stabilizes to *some* arbitrary reading, unless the system itself is leaking.
When measuring vacuum with a micron gauge, outgassing of the material in an MVAC system—that is, the oil and desiccant (even if new), hoses, seals, and etcetera—plus air and moisture that might be trapped in the system, can affect the reading observed on a micron gauge.
The micron gauge should eventually "settle down" after evacuation to less than, say, 1,000 microns in an MVAC system, unless the system or equipment has a leak. Be aware that a micron-level leak probably can't be detected even by a sensitive electronic "sniffer" unless it's a substantial leak (non-micron-level).
The best you can do is to either change every o-ring, seal, and hose in your vacuum pump setup in an effort to prevent any equipment leakage, or (presuming your setup isn't leaking) continue evacuating until the micron gauge stabilizes to *some* arbitrary reading, unless the system itself is leaking.
Member – MACS (Mobile Air Climate Systems Association)
Thankful for the responses you have received? Please consider making a monetary donation to this Forum.
Thankful for the responses you have received? Please consider making a monetary donation to this Forum.
Re: Improving vac pump perf
Last night I played with it some more. Connected my brand new 3-port Fieldpiece manifold and all 3 brand new Yellow Jacket Plus II hoses to vacuum. Got down to 370 microns after a few mins. Shut-off pump isolation valve and shut-off pump. Today I'm at ~750 microns, so think I'm OK in regards to leaks with test equip.
Searching HVAC vacuum tests shows most recommend that sys should hold below 500 microns for 20-30 mins, and others say it should hold below 500 microns overnight. May be some are referring to HVAC systems other than automotive??
Don't think my system will hold below 500 microns for more than a few mins since the test equip by itself can't do that due to outgassing??
Anyway, I'm headed to the shop for what will certainly be a long crappy job. With a little luck, I'll have it evacuating this evening and see what's up.
Searching HVAC vacuum tests shows most recommend that sys should hold below 500 microns for 20-30 mins, and others say it should hold below 500 microns overnight. May be some are referring to HVAC systems other than automotive??
Don't think my system will hold below 500 microns for more than a few mins since the test equip by itself can't do that due to outgassing??
Anyway, I'm headed to the shop for what will certainly be a long crappy job. With a little luck, I'll have it evacuating this evening and see what's up.