View Full Version : Imperial vs Metric

17-06-2001, 05:06 PM
Techs use either imperial or metric temperature statements , this is a bind for those either used to one or the other. 30F for instance, whats that in Celcius. I know, I can get out my chart and see .
I guess this is a difficult one and standardising either would be impossible, techs are too entrenched depending on what there comfortable with using.
In that case Ill just have to display a Celcius - Farenheit conversion chart next to my monitor.

22-03-2002, 04:09 AM
30 F is approximately -1 C ... don't ask me how I know, I just Do! *S* Hey bud! More often than not we are converting from C to F in Canada...

22-03-2002, 02:08 PM
-40c = -40f

When working with the scientific community, I always assume that they're talkin' metric. The in-house maintenance man is usually the go between, and when he tells me that Mr. Scientist wants the space at 0 degrees...... I ask Fahrenheit, or Celsius?


It'll usually take about a week before (he) gets back to me with the answer!

Right now, I have a small window with an online F to C calculator that I can use as I'm on the forumn.

Prof Sporlan
22-03-2002, 02:50 PM
No doubt the Celsius scale should be used in favor of the Fahrenheit scale.... it seems more consistent for water at atmospheric pressure to freeze and boil at 0 and 100 respectively, versus 32 and 212. This coming from one who has at times questioned the logic of the other primary S-I units of measurement, i.e., meter and kilogram (http://www.mel.nist.gov/div821/museum/timeline.htm) :)

If the Prof had his way, he would use the Celsius scale, but retain the lb mass and feet for length. He'd do away with ounces, tons, etc. Mass units would have to follow same prefixes used by the S-I system... kilopounds (kips), millipounds (mips).... Same with length... no more yards, miles, etc. We would use kilofeet, millifeet, microfeet.... :) lb mass and lb force would be used interchangeably, like kilogram mass and kilogram force is used today. Mmmmm.... he would want to use 'psi' for pressure, but he just eliminated 'inches'. Better make an exception for 'inches'...... :)

22-03-2002, 08:29 PM
Yes, we in the UK are used to metric for some things but still like to see psi, funny old lot aren't we?

It screws me up when working on a digital display, such as Carrier, when in metric mode displays Celcius which is good but the pressure are in Mpa (Doh!), Change it to imperial (psi) and we go back to F.

25-04-2002, 03:56 AM
Right, and just try to figure out how to buy a fast car when it's rated in Kilowatts instead of Horsepower!

25-05-2002, 10:06 PM
3/4rters H TO K

31-05-2002, 12:22 PM
Slowly but surely...high end machinery in the US is metric this metric that. I started throwing away some american allens as not to get them mixed up with the metric stuff. I think by the next gereration tools and measurement will be a metric standard. Guess were stuck with the conversion process!

25-11-2003, 10:40 AM
kilowatts / 746 i think is the conversion for Kw to Horsies. LOL Prof Sporlan, perhaps you could have been a comedian too.

i have only ever learnt metric for everything at school. the most i worked out of my ruler which was made in china :) great to see everything made there is for great diversification! is that 1 inch was roughly equal to 2.5cm.

which ever you are comfortable using i suppose, however i think metric makes more sense in todays environment since it is of the base 10 principle...

i remember my father asking me to cut something an 1/8th of an inch long. i had no idea what the hell he was talking about lol

perhaps you could use plurals prof.

millifoot = 1
millifeet = millifoot * the amount of millfeet.
and so on an so forth...

25-11-2003, 04:37 PM
back in the 70`s when i have learned all about RAC, everything was impirial, in all the indusries the inch ruled. slowly the MM creaped in from europe and sattled very well. the same with pressure and temperatures, i still use PSI for pressure but C for temp. a KM is better then MILE,(you think you drive faster) its easier to calculate.
the prof will forgive me but so are KG much simpler then pounds, stones and bushels. this is called globalization. makes it easy for us to speak in one laguage all arround the world.
isnt this is what we are all doing here??


25-11-2003, 06:21 PM
I have to aggree with Brian.
Temps i work in Celcius but pressures in PSI. I know most pack sites work at about 20bar high side but as me what that's in PSI and i would guess about 240-250.
I hav also found controllers that you can change metric/imperial but also found you can have degree f/PSI or Degree's C/BAR never can you change them about to get C/PSI.
While on the subject, has anyone else had problems with new compressors now coming with metric pipe instead of Imperial.
I cannot remember which make it is, Poss Aspera or L'unite which means instead of just swopping straighy over you have to P*** about flareing the pipework some more.
I know it doesn't take long but i am in one of them moaning moads again !!!


25-11-2003, 06:45 PM
irecall you have mentioned the problem of pipe size in MM before so i will make you a list. copy and print it and stick onto your windscreen and while you wait in trafic jams, memorise it:

6mm = 1/4
8mm = 5/16
10mm = 3/8
12mm = 1/2
16mm = 5/8
19mm = 3/4
22mm = 7/8
28mm = 1 1/8
35mm = 1 3/8
40mm = 1 5/8
54mm = 2 1/8

i really hope it will help and about your mood, why not go to your local and drown it in a pint.


Prof Sporlan
26-11-2003, 01:20 AM
The Prof had thought at one time the weight conscious in the U.S. would eventually favor kg versus lb. But centimeters really do present a problem with waistline measurements... :D

26-11-2003, 08:31 AM
hehehe, i'm sure they do!

26-11-2003, 03:05 PM
my dear prof sporlan,

the most common way to convert to centimeters regarding your waistline is sinple: multiply the present waistline (in inches) by the number of pints you consume daily and you get it in centimeters!! LOL


27-11-2003, 06:57 AM
The trouble with conversion is when it is half-baked. In Australia we have been metric since the 1970s, but HVAC tubing is still imperial with metric names. When you buy 9mm tubing, you get three eighth. This is ok until you try and mix it with some European equipment where 9mm means 9mm.

You still buy beer by the half pint in the pubs, but they call it 285ml and it is 285ml.

27-11-2003, 09:09 AM
mmm beer.... i go for the 325ml's myself ;)

or the 200ml of rum and coke (30ml rum 170ml coke)

28-11-2003, 08:18 AM
Mmmm. Bundy & coke! My other half hates it - she says it's known as 'Old Wife Batterer' lol. Looking forward to downing a few next week! Bones, are you on the gold coast?

17-12-2003, 01:54 AM
As I'm from China,I'm not familiar with the Fahrenheit scale and inch or psi.I only know it is there,I changed 1 feet to 10 inches at first time,a big mistake!
As I worked in a company of the U.S,I have to use these unit everyday.I foud a lot of formula use U.S customary units is very simple and easy to use. E.G,If you know the head and the flow,the GHP of the compressor can be calculate with a simple formula. and some others.
but I cann't found a formula as that in my book.
surely maybe what I've see is not enough.
But I really donn't like 1/8 inch,but I like the simple formula.

05-01-2005, 01:16 AM
we use SI unit in China. I'm often confused by Imperial unit or metric unit. why is it incorporated into SI? it's help for all engineers all over the world.

05-01-2005, 04:16 PM
Here n Lebanon we are stuck between the 2 , Imperial and metric , In HVAC imperial is used for load calculation , when you go to the field Metric is used , no one knows the Imperial units lololol
Just use a unit converter such as engtools (software) that convertes any unit to any another

29-03-2008, 01:02 PM
Here's a very small but excellent converter for just about anything (eg. HP to Watts, MPH to KPH etc.)
and it's free. Google convert.exe

The MG Pony
29-03-2008, 03:14 PM
Hmmm 3 year old thread, still some one has beat it by replying to a 7 year old thread!

29-03-2008, 04:13 PM
yeah, old thread. But I don't have an idea what anyone is talking about when they say 30F superheat, or 30psi suction temp here. In australia all temps are celcius or kelvin, most pressure are KPa (unless you are talking to someone over 40yo).
Pipe diameters across the board, if it's metal whether its refrigeration pipe/plumbing or car exhaust is imperial. All plastic is metric though. End result, if I see a thread where they are talking about PSI or farenheit I stay clear of that thread, because I don't know what the hell they are talking about!

29-03-2008, 05:04 PM
I found another unit conversion software on the net. It's free.

monkey spanners
29-03-2008, 05:43 PM
If i'm measuring some thing i just use what lines up on the tape, so it can be 23 3/8" by 320mm...
Can't understand Fahrenheit, so is C for me, but this goes with Bar on gauges which i only half get by converting it into PSI in my head...
I weigh refrigerant in kilos
Milk tanks are in Gallons if old icebank type and Litres if DX or new icebank enclosed type, a 2200L icebank tank make no sense...

All we need now is metric volts, amps and ohms and we can all get really confused :p