[ga-hvac-tech]

Yeah... I suspect DC's have a sunset in the future...
Probably when new refrigerants that are not programmed in... become mainstream.

My reasoning for getting the job probes... is deeper level diagnostics.
It is easy to do day-day resi service with DC's (until a new juice is introduced)...
Probes allow for more information.

 

[mgenius33]

I have had the same experience with FP probes drifting down on a standing pressure test on systems that though time proved to not be leaking. I do not see how it would be possible for them to be temp compensating with respects to a N2 standing pressure test. How could the probes determine the average temp of N2 thought the system? And if they did have some sort of N2 temp compensation built in that would be a very bad thing for their primary use/measuring refrigerant pressure in an operating system. And unless this is a virgin system how can we account for the refrigerant off gassing and mixing with the N2?

I rarely preform "standing" pressure drop tests because I think that they are pretty useless for finding anything other than large leaks in a relatively short time. Small leaks will require and over night stand and, for me that just isn't practical nor has it proved to be necessary.

Apparently, Measurequick performs the temperature compensated tightness test. I’m wondering if this will fix the issue with my pressure test drift on my FP probes.
My old Testo 550 manifold has this test feature as well, but the 549i probes do not. I’m assuming Measurequick provides this test for the probes?
https://support.measurequick.com/knowledge-base/temperature-compensated-pressure-test/

 

[m singer]

Apparently, Measurequick performs the temperature compensated tightness test. I’m wondering if this will fix the issue with my pressure test drift on my FP probes.
My old Testo 550 manifold has this test feature as well, but the 549i probes do not. I’m assuming Measurequick provides this test for the probes?
https://support.measurequick.com/knowledge-base/temperature-compensated-pressure-test/

I am sure that if the info into MQ is 100% accurate the output from MQ will also be 100% accurate. IMO the problem lies with measuring the pressure change of a small leak in a reasonable amount of time and differentiating the pressure loss of the small leak from other pressure change factors. I think that getting positive results that you can have a hi degree of confidence in from a standing pressure test without an overnight stand is an unsolvable problem.

 

[heatingman]

Do the Appions work with the MQ app from TT tools???

I don’t believe they do.


Sent from my iPhone using Tapatalk

 

[mgenius33]

I am sure that if the info into MQ is 100% accurate the output from MQ will also be 100% accurate. IMO the problem lies with measuring the pressure change of a small leak in a reasonable amount of time and differentiating the pressure loss of the small leak from other pressure change factors. I think that getting positive results that you can have a hi degree of confidence in from a standing pressure test without an overnight stand is an unsolvable problem.

Yeah, I get what you’re saying, but the attempt is more so to mitigate the inconsistency. Certainly, there are always going to be those PITA jobs where nothing goes right, but if I could get 90% of the jobs to hold a pressure test without showing a false leak, I’d be happy. I realize everything leaks, and a standing 1 hr pressure compensated leak test may not provide 100% certainty that the system is 100% leak free. With the FP probes, I’m feeling like 90% of my jobs are showing leaks when there aren’t any. I already had one probe blow out on me, and without temperature compensation, it’s just another thing to reduce confidence in using these great probes for a leak test application. It’s almost like it’s a waste of time to pressure test because the pressure almost always drops consistently.

Again, going back to my Testo 550’s with the leak test program built in, there’s just too many parts to leak in between the pressure transducer and the service port. So, my goal is to find an ideal solitary gauge that will provide that 90% confidence factor.

My question to Jim Bergman would be, how is it that Measurequick can provide temp comp and neither FP nor Testo can provide it with their probes, but they can with the manifold sets?

 

[m singer]

With the FP probes, I’m feeling like 90% of my jobs are showing leaks when there aren’t any. I already had one probe blow out on me, and without temperature compensation, it’s just another thing to reduce confidence in using these great probes for a leak test application. It’s almost like it’s a waste of time to pressure test because the pressure almost always drops consistently.

100% we are on the same page.

 

[mgenius33]

Well, I’ve been lazy long enough, I’m gonna start using the Measurequick app more often. While there’s just standard info on the FP app, it’s basic and quick. I set up my probes on the app and I’m gonna use Measurequick on the next pressure test to see if the temp comp is the real issue I’m having. I have no clue why FP or Testo can’t integrate this feature in their apps.

 

[itsiceman]

Are you talking about a N2 pressure test that takes a change in temperature into account for any pressure change due to the temperature change or is it a pressure measurement accuracy thing you are looking for?
The way I'm reading it it sounds like the two different things are getting intertwined in the posts.

 

[mgenius33]

Not looking for accuracy as far as what the gauge reads compared to perfect actual pressure. I’m more concerned with the accuracy of the pressure change especially since higher resolution digital gauges have become mainstream. Kinda like a vacuum reading, the decay rate is somewhat more important than the actual reading, so long as it’s below 1000 microns. Back in the day an old Bourdon tube analog gauge was all we had. It was almost less frustrating being ignorant to the difference because it would be hard to see 1 psig change on a 500 psig 2.5” diameter scale.
I messed around to with the Measurequick pressure test, and I like the pass/ fail output. It also shows what the pressure should read according to the temperature change.

 

[itsiceman]

So testo and Fieldpiece apps just record start and end pressure and it's up to you to decide if there is a leak or the temperature changed?

 

[mgenius33]

So testo and Fieldpiece apps just record start and end pressure and it's up to you to decide if there is a leak or the temperature changed?

From what I can see yes, but both FP’s & Testo’s manifold sets have a pressure compensated test, odd. That’s why I’m wondering why or how Measurequick is able to do what they apparently can’t. Actually, I don’t even see where the FP probe app even offers a standing pressure test.

Maybe instead of finding some special gauge, I just go with a new Testo probe. I like the probes, but the range sucks for regular testing.

 

[jayguy]

I am sure this gage exists but not on our hourly wages.

 

[mgenius33]

I am sure this gage exists but not on our hourly wages.

The Additel 680 is reasonable just under $500. Not like we don’t already pay $375 for a micron gauge.

I just think there’s more to the pressure test that we’re not exploring. For instance when a system is pressurized we need to purge out all of the standard air inside due to a potential greater change than N2 alone. Also, when pressurizing we create heat of compression on the gas inside the system. The process begins and transfers heat to the surrounding surfaces. So, is a pipe temp clamp going to give us the results we’re looking for or do we need a temperature sensor built in? I guess we can wait several minutes for the heat of compression to balance with the tubing, but who has time to wait?
I find it odd that we’ve gone off the deep end with vacuums, but yet still use a standard gauge to pressure test with marginal results. So, before I drop $500 on another gauge, I want to explore the art of pressure testing just like we have with the art of vacuums.

 

[itsiceman]

When you unload a N2 tank it gets colder.

Is that true about air vs N2? I believe it is not with other gasses but not sure with air... I take that back. I think I remember this being tested regarding N2 and tire inflation. Multiple gasses followed the same with temp in the range we are talking.

 

[mgenius33]

When you unload a N2 tank it gets colder.

Is that true about air vs N2? I believe it is not with other gasses but not sure with air... I take that back. I think I remember this being tested regarding N2 and tire inflation. Multiple gasses followed the same with temp in the range we are talking.

Yes, I also thought unloading a bottle will make it cold because we’re reducing pressure in the vessel, the inverse is true for adding pressure to the other vessel.
I don’t know how much difference there is exactly with oxygen compared to nitrogen. Obviously we have to consider standard air is ~20.9% oxygen, ~79% and 0.1% other mixes gases (roughly). I guess using the ideal gas law you could calculate, but we have to consider density. Idk, haven’t thought about it. Which there was a PT chart for both.

 

[itsiceman]

I don't think there would be a way to keep track of temperature that close especially on a split system.

 

[itsiceman]

Yes, I also thought unloading a bottle will make it cold because we’re reducing pressure in the vessel, the inverse is true for adding pressure to the other vessel.
I don’t know how much difference there is exactly with oxygen compared to nitrogen. Obviously we have to consider standard air is ~20.9% oxygen, ~79% and 0.1% other mixes gases (roughly). I guess using the ideal gas law you could calculate, but we have to consider density. Idk, haven’t thought about it. Which there was a PT chart for both.

The pressure in the system will always be lower than when you started you wouldn't be adding heat.

 

[BBeerme]

Years ago we had to tie into the main air line, so we had to blow the system down. Pretty good sized tank, maybe 5' dia and 10' tall. I threw the blow down ball wide open, and we had to plug our ears, outlet was maybe 2". Any, ice started forming on the outlet, then small chunks of ice came lose and started blowing out. So yes, pressure change (drop) alone does absorb heat, I was surprised to see that, I mean, no state change.

When you unload a N2 tank it gets colder.

Is that true about air vs N2? I believe it is not with other gasses but not sure with air... I take that back. I think I remember this being tested regarding N2 and tire inflation. Multiple gasses followed the same with temp in the range we are talking.

 

[itsiceman]

Years ago we had to tie into the main air line, so we had to blow the system down. Pretty good sized tank, maybe 5' dia and 10' tall. I threw the blow down ball wide open, and we had to plug our ears, outlet was maybe 2". Any, ice started forming on the outlet, then small chunks of ice came lose and started blowing out. So yes, pressure change (drop) alone does absorb heat, I was surprised to see that, I mean, no state change.

Cool story but about the air I was wondering about P1/T1=P2/T2

 

[m singer]

When you unload a N2 tank it gets colder.

Is that true about air vs N2? I believe it is not with other gasses but not sure with air... I take that back. I think I remember this being tested regarding N2 and tire inflation. Multiple gasses followed the same with temp in the range we are talking.

Boyle's law applies. Gas going from hi to low pressure cools. Gas going from low pressure to hi heats.