Stal screw

[GHAZ]

Hi guys need info on stal screw R57K eg parts manual /rebuild manual thank you

[cricri]

Hi ghaz,

do you mean a vertical Stal mini screw?
then Mk1 or 2?

[GHAZ]

yes they are verticle screws

[Magoo]

R59's were pre computers and most was in manuals, big manuals. Try Johnsons Controls for data, good luck.

[The Screwdoctor]

Hey GHAZ,

R59K is a Mk2 STAL Mini. The Mk1 versions were produced up to code F. 9 indicates that it has a gearset which gives a 5900 rpm. at 50 Hz.

These compressors are pretty reliable if serviced properly. Overhaul requires the right tools (toolkit).
Do you have any specific questions? Maybe I can help you. I can ask my colleque in the UK if he has some technical info for you.


The Screwdocor

[GHAZ]

hi screw doctor i,ll strip it first and then if i get any problems i will let you know , thankyou

[antonio nunes]

Hey GHAZ,

R59K is a Mk2 STAL Mini. The Mk1 versions were produced up to code F. 9 indicates that it has a gearset which gives a 5900 rpm. at 50 Hz.

These compressors are pretty reliable if serviced properly. Overhaul requires the right tools (toolkit).
Do you have any specific questions? Maybe I can help you. I can ask my colleque in the UK if he has some technical info for you.


The Screwdocor

Hi
How r u?..I wonder if u could help me sorting out some grey areas of mine concerning down-regulating of a screw Stal compressor..thanks in advance

[Magoo]

Antonio,
the earlier versions o the Stal R series were differential pressure oil feed. If you are going to speed regulate compressor instal the auxilary/ external oil pump assembly. The oil fliters were also small suggest an external oil filter as well. 25 micron range

[The Screwdoctor]

Hello Antonio.

down regulating a STAL R5 compressor is possible because of the gearset. The R59 has a gearset 9 and with a 3000rpm 50Hz motor gives the compressor a speed of about 5900 rpm. If you go up to 60 Hz it will rev up even faster. If you want to go down in rpm it is possible (electric motor has enough power)to change gears to set 7, 5, 3, going down in rpm's. The R5HSD series have a 6000 rpm 100Hz motor regulating from 1000 up to 6000 rpm with Freguency controller . Only difference with standard compressor is fixed capacity control, no oilpump needed. The later generation F19 series have an oilpump and no geardrive but direct with coupling.

The Screwdoctor

[antonio nunes]

Hi Screwdoctor & Magoo
The compressor unit I´m dealing with is a Stal type S71E-26A, and it´s a marine app for chiller purposes..it runs on R22 and it´s as soon as air temp is < 14 degrees celsius, its capacity it´s downsized by current limiting..my main issue is what implications this has on the entalphi (kg/kJ)=heat removed from medium versus el-motor KWh input...anyhow it was a blessing to discover this site.."more will b revelead" b well

[The Screwdoctor]

Hey Antonio,

a S71 and R5 are besides they have rotors two completely different compressors, I thougt you had a question about the R5 series. Regarding your last post I'm a bit confused because you are talking about when the air temperature is below 14 degrees. Is this correct or do you mean above 14 degrees?

The Screwsdoctor

[antonio nunes]

Hi Screwdoctor..Yes I´m aware that we r talking about 2 different machines..mine is an older concept, i presume--no gear whatsoever. What I ment by air temp less then approx 14 degrees celsius is a little misguiding..the scenario is: when outside temp is around 15-14 degrees there´s not that much need for AC onbord the ship..mostly in services areas is still necessary cooling the ambient air---so within these temp. the chiller is capacity downregulated and switching on/off...the setpoint is 11,5 degrees celsius(meaning that when the return-chilled medium reaches this value, the compressor stops)...in the meantime the activity in i.e. ship services areas continues(lights & machines+ people)and the need of cooled air arises again..this process is going on at least 2 months a year around here(the ship is an ugde PAX boat transporting passengers and vehicules between Copenhagen and Oslo)..I hope I was able to enligthen the situation properly...best regards.

[Gingerair]

Hi Antonio
You may find that the plant you have on board may be sized for use in the tropics, +30c sea water temps. Can you check the original specification ?
If you're in the Baltic it will probably rarely be used to it's full capacity & will be very inefficient & expensive to run.
As far as i'm aware you cannot 'down regulate' a unit like yours. It may be better for you to find an alternative to achieve the cooling you require without having to run your plant.

When the ambient temp is low it may be better to increase fresh air supply via your air handling units.
Alternatively it may be possible to have a sea-water heat-exchanger fitted to your chilled water system, if the sea water temps are low enough to provide a useable temperature differential.

The cost of the diesel fuel used to run another generator just so your plant can be used will be frightening.

Captain Ginge :)

[antonio nunes]

Hi captain G..thanks for relating to the issue. The vessel was built in Split(Croatia) 16 years ago and it´s icy seawaters classified, so it´s was ment to sail this part of the world...what I believe is that the chilling unit was sized to cope with other climate conditions as well..since as the specifications mention: " the refrigerating capacity is stated at 32 Celsius cooling water"..my first question arises right her--> do they mean the condenser cooling water-circuit? or the cooling medium(brine=water added salt) circulating throughout the evaporator and along the ships pipping system?..
....best regards..

[Gingerair]

Hi Antonio
It's difficult to Know what 'cooling water' is in your documentation without seeing it, but it may be in reference to the refrigerating capacity at that sea water temp.
Either way it may not affect the posibility that you're trying to run your plant below it's intended specifications.
Has you condenser got a sea water regulating valve fitted ?
Have you got the correct chilled water flow through your evap ?
Are all your AHU's in good working condition ?
The list of questions could go on & on...

P.S Sorry for Hi-jacking this thread... :confused:

[antonio nunes]

Hi Gingerair..thanks a lot for your reply. I would appreciate if you could relate to some questions I have..but first of all I need to gather some information and knowlegde in order to ask as exact and relevant as possible. I´m finishing my marine engineering studies and I´m due to writte the final thesis based on this chiller unit I will get back to. Best regards.

[Josip]

Hi, Screwdoctor :)


Hello Antonio.

down regulating a STAL R5 compressor is possible because of the gearset. The R59 has a gearset 9 and with a 3000rpm 50Hz motor gives the compressor a speed of about 5900 rpm. If you go up to 60 Hz it will rev up even faster. If you want to go down in rpm it is possible (electric motor has enough power)to change gears to set 7, 5, 3, going down in rpm's. The R5HSD series have a 6000 rpm 100Hz motor regulating from 1000 up to 6000 rpm with Freguency controller . Only difference with standard compressor is fixed capacity control, no oilpump needed. The later generation F19 series have an oilpump and no geardrive but direct with coupling.

The Screwdoctor

Not exactly sure, but as I remember R59 must not be operated on 60Hz...


Best regards, Josip :)

[Josip]

Hi, antonio nunes :)


Hi captain G..thanks for relating to the issue. The vessel was built in Split(Croatia) 16 years ago and it´s icy seawaters classified, so it´s was ment to sail this part of the world...what I believe is that the chilling unit was sized to cope with other climate conditions as well..since as the specifications mention: " the refrigerating capacity is stated at 32 Celsius cooling water"..my first question arises right her--> do they mean the condenser cooling water-circuit? or the cooling medium(brine=water added salt) circulating throughout the evaporator and along the ships pipping system?..
....best regards..

I believe cooling water means water for condensation ... i.e. it can cope with other climate conditions

on the evaporator must be a name plate where you can check in/out values for refrigerant and brine


Best regards, Josip :)

[The Screwdoctor]

Hey Josip,

why not operate a R59 on 60Hz????
please explain your comment

The Screwdoctor

[Josip]

Hi, Screwdoctor :)


Hey Josip,

why not operate a R59 on 60Hz????
please explain your comment

The Screwdoctor

see attached document ...

I cannot give the right explanation (you must ask Stal, Sabroe or JCI about), but I believe Stal found something wrong at 20% higher speed ... another possibility is, they like to sell a bigger and more expensive compressor for that capacity and for that reason it was forbidden to operate this one at 60Hz

... not sure if you are satisfied with this .... maybe you can put some more light on this....

In my opinion STAL was a very good company and I believe all compressors in that time were designed for 50Hz .... with 60Hz some of them were beyond some limits...

But, .... I can be wrong too.....

Best regards, Josip :)

[antonio nunes]

Hi, antonio nunes :)



I believe cooling water means water for condensation ... i.e. it can cope with other climate conditions

on the evaporator must be a name plate where you can check in/out values for refrigerant and brine


Best regards, Josip :)
Thank you Josip..that´s what I believe as well..brine return from ship areas at 32 celsius seems like way on the egde to me.
But in that case, I can deduct that the chiller unit was designed for other waters then the scandinavians. This might be the reason why the screw-kompressor Stal S-71 is current-limited to 300 A....(normal current= 720 A) some part of teh year. My major headache so far is to determine how much this affects its efficiency..Sabroe litteratur gives a very optimist picture of capacity control performed by the micro-processor Stalectronic 600..but I witnessed weeks in a row how often the compressors on/off ocurred...and i´m positive this kind of opreation can´t be economical. Best regards..

[The Screwdoctor]

Hey Josip,

looks that you are right with the R59 on 60Hz. The other gearsets seem to be no problem, never came accross the manual sheet you found. I'll go through my STAL library to check if there is difference in refrigerant, R12/R22/NH3

And you are right about STAL

The Screwdoctor

[Magoo]

Hi Screw Doctor.
I agree, I have never come across the sheet posted by Josip.
Out of interest, what oil would you have used in an R5 series / R-22. Low temp application. I had huge problems keeping oil in cast iron cyclonic separator set up. That is until I retro fitted oil charge to Mobil SHC 426.
Also the R5 series is a totally different animal to a S71.
Back to initial problem, glycol return to evap., would create havic in evaporator at + 32 'C.

[Gingerair]

Have seen the same sheet that Josip posted but for R22 & R717..

:cool:

[Josip]

Hi, The screwdoctor :)


Hey Josip,

looks that you are right with the R59 on 60Hz. The other gearsets seem to be no problem, never came accross the manual sheet you found. I'll go through my STAL library to check if there is difference in refrigerant, R12/R22/NH3

And you are right about STAL

The Screwdoctor

No, there is no difference, why you are thinking there is some difference?

Best regards, Josip :)

[The Screwdoctor]

Hey Magoo,

the cyclone oilseperators which are used on the Mk2 series have several different coalesser filter setups to choose from, because of high oilconsumption in certain cases. Usually low evaporating temperatures have no filter at all when running on R22. At high evaporating temperatures the oilconsumption is usually higher and a coalesser is needed. I have seen many R5's running on SHC226E. I can imagine that when the oil is very thin at low temperatures the oil consumption at discharge temperature will be high. There is a manual sheet with suitable oils for the R5. I have to check on that one.

The Screwdoctor

[Magoo]

Hi ScrewDoctor.
The particulat plant I inherited was on a spiral that went through pull down condition daily, the Staltronic controller ramped loading real quick. So after fitting a few timers and changing the oil, system went fine after draining truck loads of oil out of surge drum.

[Grizzly]

Hi Guys.
Just maybe the attached may be relevant?
Or at least of interest to someone.
Grizzly

[antonio nunes]

6349
Hi everybody..does any of yoy people knows what "theta out" and "control setpoint" stands for?..( as shown in picture above, taken from control unit Stal-ectronic 600)
..thanks in advance Ant