Testo 550/557

[itstony]

Thinking about buying a Testo 550/557 and unable to see online how good the Vac reading is and what scale it uses.
Does anyone use either of these for evacuation? Or is a stand alone vacuum gauge advised?

[Brian_UK]

Looks liker a separate gauge for the 550.... resolution 1 inHg

http://www.testo.us/online/embedded/Sites/USA/MainNavigation/SectorsAndProducts/HVACR/550_Quick_Start_Guide_2010.pdf

and the 557 does provide some measurement but with a resolution of 500 microns.

http://www.testousa.com/refrigeration/images/stories/docs/557 quickstart-lores.pdf

[itstony]

Thanks Brian. Looks like a stand alone vac gauge would be needed with the 557.

[monkey spanners]

Thanks Brian. Looks like a stand alone vac gauge would be needed with the 557.

Would need one with the 550 too as it only has a coarse vac gauge, equivalent to a standard compound gauge.

I have heard that lots of these manifolds with inbuilt vac gauges (various makes) can suffer from contamination (just think of all the oil etc that goes through a manifold in normal use) so imho a separate gauge would be a good idea.

[install monkey]

torr gauges are meant to be fitted at the furthest point from the vac pump- im finally sold.im treating meself to the 550's with case,probes- sick of them refco's with leakin sight glasses and crap cases- 2yr warranty-climate ctr are gonna hate me when they come back in 729 days smashed to bits!! haha

[itstony]

The 550 only reads a negative pressure, but the 557 does specifically read vacuum.
I do feel a stand alone vac gauge is a good idea. Still not clear on what the lowest micron scale is, believe it may only be 500?

[Brian_UK]

My electronic vacuum meter reads down to 25 micron, CPS VG100

http://www.cpsproducts.com/site/ProductsHTML/ElGgsMeters.html

[Artel dan]

i was looking at the 557, and reading on other forums. it said they didn't suffer from contamination? re vacuum gauge, how can this be?? also said they adjust them selves to atmospheric pressure. as the 550 doesn't.
I like the idea of having a 4 way manifold too. Does anyone have any thoughts on this? Cheers Dan

[nike123]

If vacuum sensor read pressure directly (piezoelectric) than it cannot be contaminated with oil.

http://www.teledyne-hi.com/products/thps760.htm

Usualy high vacumm gauge are thermal conuctivity sensor which measure heat disipation. If that sensor is contaminated with oil or simmilar, heat disipation is afected and you have false reading.

[install monkey]

update- had me testo 550's 2 months- didnt use em for first few weeks, now after a bit of manchester sunshine(torrential downpours) now the buggers wont zero, currently low side in a 12 inch vac nd hi side at 25 psi!!!- i did pressure test a 410a system to 40 bar- note it is stamped on the back of the sight glass 40 bar!- so theyve been returned to testo, as even removing the batterys doesnt reset it!!- still got 22 month warranty though!

torr gauges are meant to be fitted at the furthest point from the vac pump- im finally sold.im treating meself to the 550's with case,probes- sick of them refco's with leakin sight glasses and crap cases- 2yr warranty-climate ctr are gonna hate me when they come back in 729 days smashed to bits!! haha

[stufus]

http://www.yellowjacket.com/system/files/imagecache/product_lightbox/products/full/40812.jpg
Hate to say it, but I did tell you.HAHA
Cheers
Stu

[robertniez1961]

Just did a system evacuation, yes it measure the level of vacuum in "Hg but after that my 550 doen't measure the probe temperature anymore. So I don't have any means of checking the sub-cooling and superheat anymore...

[install monkey]

the uk ones temp is based on pressure- to use the pipe probes turn it off, hold the top left and right buttons (set and mode-i think) then turn it on, keeping the set and mode pressed until fact off is displayed then you can scroll through for superheat/subcool

Just did a system evacuation, yes it measure the level of vacuum in "Hg but after that my 550 doen't measure the probe temperature anymore. So I don't have any means of checking the sub-cooling and superheat anymore...

[chillerman2006]

update- had me testo 550's 2 months- didnt use em for first few weeks, now after a bit of manchester sunshine(torrential downpours) now the buggers wont zero, currently low side in a 12 inch vac nd hi side at 25 psi!!!- i did pressure test a 410a system to 40 bar- note it is stamped on the back of the sight glass 40 bar!- so theyve been returned to testo, as even removing the batterys doesnt reset it!!- still got 22 month warranty though!

And I am gonna Blame the Monkey if my set f**k up too

You got me buying testo's instead of taking the advice from our baraclava clad friend

I'm listening to the tin man in future ;)

R's Chillerman