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Brian_UK
17-10-2007, 08:50 PM
I was searching the web, as you do, and came across this technical manual which has some useful information in it.

Although not new it will please some because it is in "English Units", thats °F and psia/psig :)

http://www.me.umn.edu/courses/me4131/HTMLPages/LabManual.htm

superswill
17-10-2007, 10:38 PM
looks a good read,thankx brian will put the kettle on and have a swat

US Iceman
18-10-2007, 03:05 AM
Hey Brian,

Do you mean to tell me that the English are no longer using English units??? What's up with that?:D

Brian_UK
19-10-2007, 12:09 AM
You know us, whatever the EU hints at, we have to do.:eek:

I don't mind working in either unit but I remember years back when we stopped getting cfm, fpm and gph for commissioning work.

The "experts" went for m³/s etc which meant figures in three or four decimal places. The numbers were bad enough the major problem was getting them on the forms that had to be completed. ;)

Mind you, the EU has finally allowed us to keep our pints and lbs/ozs - big deal:D

John Hunter
19-10-2007, 12:29 AM
Hi Folks
Talking about the comparison between the SI and the English systems being older in the tooth I still at times figure things in HP, Tons & BTU's but practice has also necessitated the use of the SI system . Someone asked me the other day what a HP was in watts . I have always used the conversion that 1 HP was 8000 BTU's on Chiller modes and around 4000 BTU's on LT modes. So the conversion to SI would convert the above to 2342 Watts CT and 1171 Watts LT.
I don't use HP much now a days so am I correct.
I am beginning to spend too much time on these forums, must go and do some real work

Brian_UK
19-10-2007, 12:39 AM
[going off topic]
I have a little bitch at newspapers or magazines that mix their measurement units.

A fishing magazine that I read recently was discussing a new rod that would handle a 50gram weight. In the next sentence they are talking about using a 4oz (ounce) weight. I can't keep up, it drives me crazy ;)

Or newspapers that, allowing for the fact that our, UK, children are supposedly poorly educated, produce a scare headline of...

20% of people are XXXXX however 1 in 3 are doing alright. What's wrong with saying 33% ?

Mind you I have to laugh sometimes on the TV show Time Team , an archeology program, when one of the excavator drivers is told to dig a trench a metre wide and 30 feet long - come on guys, get your act together:D
[end rant]
sorry.

Tony
20-10-2007, 10:29 AM
Hi John,

sorry but 1HP is 746 watts

John Hunter
20-10-2007, 11:32 PM
Hi Tony:)
That's right for energy but not in refrigeration measurement I don't think.
Power.1 HP = 2545 btu/hr. 1 kWh = 3142 btu/hr. So 1 HP = 2545/3142 = 746 kj/sec = 746 watts.
Refrigeration : Old standard. 1 HPr = 8000 btu/hr (Med Temp): 4000 btu/Hr Low temp.
It shows how confusing it can be to. :confused:

wambat
21-10-2007, 12:05 AM
Definition of Refrigeration Horsepower
The generally accepted definition is: High Temperature refrigeration, 1 Hp = 12,000 Btu/hr (1 Ton) Medium Temperature refrigeration, 1 Hp = 8,000 Btu/hr Low Temperature refrigeration, 1 Hp = 4,000 Btu/hr These definitions will help you identify approximate compressor or system capacities as sometimes listed in various manufacturers’ catalogs. :D

John Hunter
21-10-2007, 12:33 AM
Thanks Wambat.
Regards JH

taz24
21-10-2007, 01:55 PM
Definition of Refrigeration Horsepower
The generally accepted definition is: . :D


Definition of refrigeration horse power.

How manny horse's it takes to pull a tired fridge engineer out of bed at 0200hr in the morning to answer the phone and respond to the next breakdown:)

taz.

johnyfreon
25-10-2007, 01:38 AM
thanks a lot for the link.

Maubi
07-09-2009, 09:31 AM
Hi Brian UK,
I would like to thank you personally for directing me to the above website. Not everyone who visits or becomes a member of this site: are engineers, technicians or even knowledgeable in the science of heating/cooling. So, after opening up the site; I have spent eight hours going through all the materials. Having learnt a lot, but it is only a tiny fraction of the information shared by the college. Please post other websites that offers online tutorial on Domestic Refrigerator/Freezers.
Thanks again,
Maubi