semi-hermatic compressors

[jakb21599]

Just wanted to know what the difference was on compressors for low temp, medium temp and high temp ? If you have a 5 HP power compressor. Horse power is horse power correct ? So what is inside the compressor that is different and makes it a high, med , or low temp compressor ? I know the oil is different in them depending on ***** used. But what else is different form one to another ? Thanks for your input

[monkey spanners]

Lower temp stuff has bigger displacements for the same motor power, e.g. some Prestcold compressors have three different displacements for the same motor input power to cover different temperatures and refrigerants.

[jakb21599]

Reason i ask is that i came across a copeland high temp compressor ( going off of serial # ) that is running a freezer and has been for 7 years and they have not had any issues with it not keeping temperature. so that is why i was wondering. what kind off damage will it do to compressor if any by using a high or medium temp compressor for a freezer ? what about using a low temp compressor for a high or medium temperature application ? Whats the pros and cons off this ?

[mad fridgie]

Why would you choose to ingnore the manufactures recomendations, if you have the choice.
It is easier to explain why not to use an LT machine for HT application.
If you understand that all ac ompressor is doing is lift the pressure of a certain mass, the more mass and the greater the pressure increase the more work has to be done (bigger moter) so a LT machine, has less dense refrigerant passing through the comp (less mass) due to lower pressures. As the suction pressure increases so does the mass being moved. So you get to a point where the mass (weight) to be shifted is greater than the moter can handle, the moter overheats or stalls. (this why at times we uses MOP valves, CPR or comp unloading at high loads)
Using HT for LT application, this comes down to cooling of the moter/discharge temp. (gas cooled moters)

[D.D.KORANNE]

High & medium temp range of semi hermetic usually will have high kw motor compared to low temp semi-hermetic . This is due to low mass that the low temp comp will handle for the same displacement .

Besides, low temp semi-hermetic comp motors are exposed higher discharge end temperatures hence needs protection like injection cooling , water cooled jackets or overhead fans .

[benijoseph]

Mr, j99. OF#3 26/7/11
designing of compressor matters a lot, any compressor any application,may work but it will not perform,like overloading a vehicle,a engineer, a doctor,a politician all r human-being all cant do same job.
rgds,

[chillerman2006]

Mr, j99.
designing of compressor matters a lot, any compressor any application,may work but it will not perform,like overloading a vehicle,a engineer, a doctor,a politician all r human-being all cant do same job.
rgds,

Lad's you need to check out this post about compressors

Its all about the lube/stars & fluff in the system

It covers some designer oil coatings that make them run like new

& roast a spit ect ect ect

http://www.refrigeration-engineer.com/forums/showthread.php?32537-related-to-proper-handling-of-home-type-copeland-scroll-compressor-(oil-related)

[Steve Wright]

Valve plate design is one area of difference generally high temp has more horsepower for a given displacement than low temp.