View Full Version : Reading compound gauges

14-05-2002, 11:21 PM
Could someone tell me if there is a book on refridgeration/air-conditioning with a very informative chapter on reading and understanding compund gauges and what to look for?

15-05-2002, 06:27 AM
There should be several books out there. But what you ask seems a simple question.

Look at the given pressure on the gauge. Follow the needle inward to the center and see what color lines it crosses and the corresponding numbers. Follow the colored lines on the inside of the gauge dial counter clockwise. Match the refrigerant to the corresponding line.

Where the needle intersects (crosses) a colored line, the listed refrigerant on the gauge for that colored line indicates the temperature of the refrigerant you are using (or checking)

If you have R22 and a pressure of 62psig. The corresponding temperature of the refrigerant should be somewhere around 35-40 deg F or whatever temperature scale your gauge has.

17-05-2002, 09:15 PM
Hi Zolar

Just to avoid any confusion, what you state is perfectly true, but only for refrigerant in a saturated state.

R22 @ 62 psig might correspond with x deg C in its saturated state but what if the refrigerant was in a superheated or sub-cooled state...the temp wouldn't equate to the pressure.


18-05-2002, 02:05 AM
my problem is not knowing what i should expect from the refridgerant in pressure/temperature readings on the gauge and if there is actually a problem? a lack of understanding with reading guages and using the data to fualt find.

18-05-2002, 05:56 PM
Send an email to marc@techmethod.com and enquire about "TECH Method Lesson Series". It is exactly what you are looking for. :)

27-05-2002, 12:19 PM
There are a number of factors that effect pressure readings. Saturated temperature is the obvious one because it is marked on the gauge face, though this and the evaporator / condenser performance can be affected by superheat and the effects of pressure losses in the lines and in the component itself. It's not as straightforward as it appears.
To answer your question, there are lots of books around, but some are quite accademic and most use imperial values.
There is an excellent new book in 2 volumes, available in the UK, all in SI units, that deals with the basics of refrigeration, and repair / troubleshooting techniques that may suit you. It also does electrics and teaches the old fashioned way through worked examples.
I'm not sure if the moderator likes product endorsements on this site, so if you mail me direct I'll send you the publisher details and you can judge for yourself.

27-05-2002, 08:00 PM
Probus can you send the details to me. many thanks kitt3n@btinternet.com

28-05-2002, 09:23 AM
All done. Good luck with your studies.

14-06-2002, 09:16 PM
Got the books, cheers probus!

08-04-2004, 09:58 AM

were those books what you were looking for? thats the kind of information im after aswell if they were good what were they?????

27-04-2004, 11:14 AM
You can post it here.