PPC2AF

[MIRCS]

Is everyone taking K actions when calibrating this unit.

[Old-Navy]

The PPC2 that I have has had "J" actions for quite a few cycles.  The one I had at F.E. Warren had a "K" action usually every third cal.

[MIRCS]

The two I have here had a "K" action every cycle. For the past year they have had "J" actions, due to the fact that I stopped performing the Auto Zero on the Low Transducer.
This has solved my problem. Art Burris @ AFMETCAL has been trying to have the requirements for the AutoZ on the low RPT removed from K6-3045, though it keeps getting dissapproved from those above him.

Not performing the AutoZ on the Low RPT has solved my problems with the unit.

[Aaron]

I had K actions the first couple of cycles but I was able to correct the problem by changing my AutoZero configuration.

I was monitoring the vacuum level at one of the output ports on the Key Vacuum System using the GPH-320C Pennington Gauge. The gauge was indicating that I had more than enough of vacuum but I was still getting large variations in my PA(z) values after each AutoZero and the unit was barely meeting specs even after alignment.

I decided to verify the vacuum level at the PPC2 Autozero port, so I calibrated my VT-6 Vacuum Gauge and DV-6 Tube for a 40 micron level using the 80-6A, and tee'd the tube off the vacuum hose at the port. Sure enough I wasn't getting the minimum 40 millitorr at the Autozero input. I changed out the vacuum hose for a larger diameter hard plastic type and achieved <40 millitorr with no problems. I haven't had a k action since.

Hope this helps.

[MIRCS]

Yeah did the same thing and it was still pulling my PA values off to much and all the low ranges where out of tolerance. I will post some email traffic i have on this tommorrow. It is from Martin Girad and Art Burris. Remember that the PPC2AF is the only thing from DHI that uses other than atmosphere for the AutoZ routine

[MIRCS]

Here is some of the emails on the AutoZ

Mr. Dale,

Based on the information I have received from DHI and your conversation with DHI, I would recommend that you do not perform the auto zero every 60 days. Not performing the auto zero would not void the calibration. Let me know the results of your calibration.

Thanks,
Art Burris

-----Original Message-----
From:    Dale Charles N Civ 347 MXS/LGMD [mailto:charles.dale AT moody.af.mil]
Sent:   Wednesday, August 13, 2003 3:31 PM
To:   Burris Arthur I CIV AFMETCAL/MLEM
Subject:   PPC2AF Auto Zero

Mr. Burris,

After speaking with DHI and you on the problems that we continually have when calibrating the PPC2AF.
The problem seems to be the auto zero function. Since it seems that DHI is going to change the way the
Auto zero routine is performed. I was wondering if we could not perform the auto zero every sixty days on our two units and also before beginning the calibration as stated in 33K6-4-3045-1. This will help prove that the auto zero routine is what is throwing off the calibrations, and making the low ranges out of tolerance every calibration.

Thank You,


Thank you for the information. Your observation is useful.

From the data we have collected so far, it is clear that in
some instances, the AutoZ of the Lo RPT is causing more harm
than good. However, this is not systematically true.

Happy holidays,
Martin Girard

edit:  Post edited to change e-mail address making it unrecognizable to spambots.  - Jesse

[Velasco]

The PPC's seem to be stable if you are using very large diameter vacuum hose and suck them down way low ( I use 30 mTorr I believe, but I'm not standing in front of vac gage so I might be wrong about this). I have been able to get repeatable numbers everytime (Paztare or something like that). I like PPC's very uch, though new K pro change (IOS) makes cal suck some, now you must check high ranges at psia (vs psig before). PPC2 is da bomb! It is a very high use piece of equipment.

[flew-da-coup]

I worked in a type IIA PMEL and calibrated several of these. Getting a good PAZ Tare was never an issue for us. The problem we had was that they rarley were in tolerance. There will be at least 2 ranges out of tolerance. I know it wasn't customer abuse because the 2 in our own lab would never pass a cal. If you ever had to run a full cal on a PPCII you will agree that these things are pieces of CRAP! The Air Force should have never bought them. 

[Velasco]

Ha I work IIA now, PPC's are very stable. Its the newer airmen (or some rock NCO's too) who suck oil into them or treat them rough taking them onsite or moving them that causes the problem. They treat it likes its a torque wrench, its going to flake out. There are plenty of lab items that are treated like crap by lesser experienced or "just don't care" airmen. We all know those people that make us grit our teeth when we see them using a delicate standard, but you can't really do anything about it if they "outrank" you.