pipe sizes

[dunny123]

Hi there,iv been doing refrigeration for about a year now,both install and sevice.Im still pritty new to it an am going through college.
The problem i have is pipe sizes,if an engineer asks me to pass him some 5/8s pipe,i struggle to work out which is which.Any advise on how to remember pipe sizes quick?Maybe its becouse at my age you get tought cm,mm not inches.ie i could pick out some 15mm pipe instantly,also 100mm ducting.please help,thanks.

[paul_h]

you claim you only know metric but are having some problems with 100mm ducting?
I've been there with the copper, and embarrasingly it did take me a while to learn
all sizes approximate, I come from a metric country and these have not been looked up. They're just from memory but aren't wrong. If in doubt divide the bottom fraction by 25, then times the top fraction by the result.
eg for 5/8 = (25/8) * 5
= 3.125 * 5
= 15.6

While you're learning dont be afraid to buy a cheap digital electronic caliper to keep in your pocket. They only cost $20, and could save big dollars if you are sent out to site to measure and order hundreds of metres worth of pipe.

You don't have to do those calculations each time, just memorise these numbers:

1/4" = 6.6mm
3/8" = 9.8mm
1/2" = 12.5mm
5/8" = 15.6mm
3/4" = 19mm

measure the pipes in millimeters and convert to the closest imperial measurement

[taz24]

.please help,thanks.

Don't worry about it it will come with experience.

You can buy or get free from trade shows a little plastic disc that has most pipe sizes cut into it up to about 7/8.
You can get the from NRS, HRP or the like, just keep it in your pocket and pop it over the pipe to indicate which is which.


I've been doing it a few year longer than you and I see learners confuse 3/8, 1/2 and 5/8 so don't worry about it.

The worst thing you do is mix up 5/8 fridge pipe with 15mm water pipe. Both similar size but one will not take the pressures of the refigerant.

Cheers taz.

[dunny123]

What do you mean i claim to only know metric?are you questioning that?
And if you read the post correctly,it says i could pick out 15mm instantly,ALSO 100mm duct.So no im not having problems with 100mm duct,thanks.
Thanks for the reply and the convertion sizes.
A little advice,read the quetion before suggesting `im claiming to only know metric`.

[dunny123]

nice one taz,thanks for that mate.
I have been on nrs,and hrp websites and carnt see it on either.Do you know what there called mate?thanks again.

[taz24]

What do you mean i claim to only know metric?are you questioning that?
And if you read the post correctly,it says i could pick out 15mm instantly,ALSO 100mm duct.So no im not having problems with 100mm duct,thanks.
Thanks for the reply and the convertion sizes.
A little advice,read the quetion before suggesting `im claiming to only know metric`.

When you reply to someone include their quote in your reply, then we will know who your moaning at.

As it is I don't think Paul was criticizing you just comenting on our transition from imperial to metric but still we use the imperial measure.

Thats another thing that comes withage, tollerance.



Cheers taz.

[dunny123]

ok taz,thanks for your coment.Maybe i was a bit quick to repy harsh.But i come on here for advice,so when someone puts that i claim to only know something,i take that as they are questioning if im telling the truth or not.refrigeration engineer or not.

[Brian_UK]

OK guys, wrists slapped all round.

Dunny, I know of the pipe sizers that the others have mentioned but in the absence of getting one you could try and make yourself one.

I have one which is from the boating world and relates to rope sizes, but it's all the same.

Get a piece of flat material, sheet metal, thin plywood, and cut a VEE shape in it.

You can then place a marker along one side of the vee at the various diameters that you are looking for.

When you need to check a piece of pipe/tube simply slide your guage over the tube and read off the size.

[Grizzly]

nice one taz,thanks for that mate.
I have been on nrs,and hrp websites and carnt see it on either.Do you know what there called mate?thanks again.

They are called Pipe Gauges as Taz says they come as a circle with semi circular recesses. Each one having it's relevant pipesize printed or embossed by it's recess.
Also come in rectangular form. Very handy to carry in your toolbag.
Good for copper pipe sizes no good for Steel though.
Steel pipes Have much thicker walls to them, so there O.D. is much larger than their I.D/ BORE.
I do the same as Paul H and carry a digital Vernier this coupled with the pipe size chart in my Zuez book will normally enable pipe recognition.
Grizzly

[dsp]

Hi Dunny,
It comes down to experiance we all started somewhere. I have a cheap set of plastic calipers and they have done the trick for me!

[dunny123]

Thanks alot guys,you have helped me on this one.
I have just orderd some digital electronic calipers from ebay,£5 nice one they should do the trick.

[Josip]

Hi, dunny123

Thanks alot guys,you have helped me on this one.
I have just orderd some digital electronic calipers from ebay,£5 nice one they should do the trick.

finally you are happy..."with small help of your friends"

seems was not necessary to write down this

http://www.refrigeration-engineer.co...0154#post90154

what do you think....just little more patience

Best regards, Josip