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ingherrera
28-06-2006, 10:13 PM
I need a MYCOM's manual, because i have to select an oil for an ammonia system, and want to see what is the MYCOM'S recomendations.

Brian_UK
28-06-2006, 10:27 PM
Have you tried contacting Mycom direct through their website -
http://www.mycomus.com

Josip
28-06-2006, 11:11 PM
Hi, ingherrera :)


I need a MYCOM's manual, because i have to select an oil for an ammonia system, and want to see what is the MYCOM'S recomendations.

See if this is ok for you ;)

Best regards,

Josip :)

NoNickName
29-06-2006, 07:22 AM
Ridiculous time schedule.

Josip
29-06-2006, 09:47 AM
Hi, NoNickName :)


Ridiculous time schedule.

Why you think so?

Best regards,

Josip :)

NoNickName
29-06-2006, 09:50 AM
1000 hours check the oil
10000 hours major overhaul

In one year, a plant working 24/7 adds up 8700 hours.
I can't possibly tell any customer that the compressor he/she bought has to be rebuilt while warranty is still pending.

Andy
29-06-2006, 10:08 AM
1000 hours check the oil
10000 hours major overhaul

In one year, a plant working 24/7 adds up 8700 hours.
I can't possibly tell any customer that the compressor he/she bought has to be rebuilt while warranty is still pending.

Hi Nick:)

service intervals given here are common to all manufacturers:)

Most compressors that are worked hard run 5000 to 6000 hours a year;)

What this equates to is a top end inspsection every year (valves checked) these may be replaced or allowed to run another year dependant on wear and hours run. The next year the piston rings and valve plate will usually be changed and the third year the bearings will be replaced.

You can let them run until something smashes, but that is not preventative maintenance, anyone can change the oil and let it run:(

You may get 30000 hours out of a set of main bearings, but all you are doing is shortening the life of the compressor shaft, which is the most expensive part.

These are high tolerance high effeciency compressors, unlike the commercial semi compressors, which sacrifice the effeciency for longevity:eek:

A semi will run for years at high speed on the original bearings, but the energy consumed would be much much greater than any industrial compressor, the chaep compressor is the high tolerance high effeciency compressor that has to be maintained on a on going basis, the real enviromentally friendly option:)

Kind Regards Andy:)

NoNickName
29-06-2006, 10:33 AM
Hi Nick:)

service intervals given here are common to all manufacturers:)

No, they are not. Bitzer do not want the oil to be replaced EVER on the screw semis range.



Most compressors that are worked hard run 5000 to 6000 hours a year;)

And?
We've got scrolls from copeland running 8000 a year in CCUs.



What this equates to is a top end inspsection every year (valves checked) these may be replaced or allowed to run another year dependant on wear and hours run.

And this is a nonsense. Please let me know a single industrial plant who can accept an offline of one day for programmed preventive maintenance of the cooling system. Not in the UK. I've got a number of plants with our chillers and the customer would not stop them even for replacing a single contactor.



The next year the piston rings and valve plate will usually be changed and the third year the bearings will be replaced.

Nonsense in a teapot. It takes less time to replace a compressor than overhaul it.



These are high tolerance high effeciency compressors, unlike the commercial semi compressors, which sacrifice the effeciency for longevity:eek:

Yeah, sure. At least this is the spam what they tend to feed us with.

Josip
29-06-2006, 12:00 PM
Hi,


No, they are not. Bitzer do not want the oil to be replaced EVER on the screw semis range.

Maybe on ***** plants, but with ammonia we have to change oil filters every 3 months and oil each year(Bitzer screw). That plant is new one (2 years old) installed to liquify CO2 in one brewery.


And?
We've got scrolls from copeland running 8000 a year in CCUs.
For how many years?


And this is a nonsense. Please let me know a single industrial plant who can accept an offline of one day for programmed preventive maintenance of the cooling system. Not in the UK. I've got a number of plants with our chillers and the customer would not stop them even for replacing a single contactor.
Until is broken, what then?


Nonsense in a teapot. It takes less time to replace a compressor than overhaul it.
What about compressors with input power on shaft of 200-355 kW?


Yeah, sure. At least this is the spam what they tend to feed us with.
Industrial compressors are running 20-30 or more years with proper maintenance. I am living witness ;)

Many years ago I have been told (by people from Stal-Astra Sweden) you can build only two types of refrigeration plants:

1. Cheap plant without maintenance usually with short life - expensive

2. Expensive plant with maintenance to assure long life - cheap

Hope other guys will come with comments too ;)

Best regards,

Josip :)

Andy
29-06-2006, 12:28 PM
No, they are not. Bitzer do not want the oil to be replaced EVER on the screw semis range.



And?
We've got scrolls from copeland running 8000 a year in CCUs.



And this is a nonsense. Please let me know a single industrial plant who can accept an offline of one day for programmed preventive maintenance of the cooling system. Not in the UK. I've got a number of plants with our chillers and the customer would not stop them even for replacing a single contactor.



Nonsense in a teapot. It takes less time to replace a compressor than overhaul it.



Yeah, sure. At least this is the spam what they tend to feed us with.

Proper industrial users have standby plant just for maintenance, they can't afford not to have:)

Mycom are now using a hitachi scroll with aluminum windings on Ammonia, we will see how this goes

Nonsense in a teapot:D :D
try replacing a 8WB Mycom in the time it takes to do an overhaul, well you probably could but it would take a crane to do so, bit of a nonsense really:D

You have hit the nail on the head, this short service interval is whay recips died out for a few years. The reason they are now popular is the screws have poor part load effeciencies:eek:

When you take into account the seasonal EER the recip wins hands down.

We sell a range of packaged chillers, but we also seel ammonia chillers with water cooled condensers and flooded chillers, for people who care how much electric they are using:) and what effect this has on the enviroment;)

Kind Regards Andy:)

NoNickName
29-06-2006, 12:56 PM
Proper industrial users have standby plant just for maintenance, they can't afford not to have:)

At least they should have one backup. Ordinary reality is much sadder than that.



try replacing a 8WB Mycom in the time it takes to do an overhaul, well you probably could but it would take a crane to do so, bit of a nonsense really:D

It all depends on proper chiller design. For our air cooled and water cooled, compressors are replaced and restarted in less than 6 hours.
Overhauling (on-site or off-site) is a matter of days.



You have hit the nail on the head, this short service interval is whay recips died out for a few years. The reason they are now popular is the screws have poor part load effeciencies:eek:

Well, you may be well right, BUT! ST microelectronics in Milan runs a plant with a total overall power consumption of over 100MW. Would you reckon what difference few dozens kWh per year makes?



When you take into account the seasonal EER the recip wins hands down.

Definitely.

US Iceman
29-06-2006, 03:24 PM
this short service interval is why recips died out for a few years.

And I always thought the screw compressor salesmen did such a nice job.:p

I have heard some of these stories used to sell screws. 100,000 hour bearing life, no valves to replace, more efficient, can ingest liquid with no harm, cheaper to install, etc, etc.

When screw compressors were being sold some time ago, the salesman all said variable Vi was better than fixed Vi.

Recip compressors were less efficient than screws. All sorts of sales tactics were being used.

I think the simple fact is; both compressor types have some benefits that can be utilized... if done properly.

Screws can operate at high pressure ratios more efficiently. They require smaller areas for the equivalent capacity (on big systems).

But, I have never heard a salesman tell the owner the screw compressor is a lot more inefficient than a recip compressor at part load when trying to sell a screw.

And... I have never heard a screw salesman say recip's already have variable Vi. They don't even need control systems for variable Vi.:cool:

Although I would like to see someone add a manifold to a recip for economizers.:D

I'm in agreement with Andy. A lot of arguments are used to sell one compressor over another type. I think the arguments are based on what the salesman is trying to sell. Sometimes these are vary one-sided.



The reason they are now popular is the screws have poor part load efficiencies:eek:


I think people are starting to get smarter about how they select compressors.

There's a place for both. Now people are starting to use VFD's on screws. That's a big benefit for part load improvements.


...runs a plant with a total overall power consumption of over 100MW. Would you reckon what difference few dozens kWh per year makes?


2 dozen kWh is not much a savings.;) However, on the serious side, if the plant is using 100 MW, there has to be some room for improvement in energy use.



Many years ago I have been told (by people from Stal-Astra Sweden) you can build only two types of refrigeration plants:

1. Cheap plant without maintenance usually with short life - expensive

2. Expensive plant with maintenance to assure long life - cheap


I quite agree with this.

Number 1 is usually a system that is designed to be cheap on the first install price. Then the system is operated in a "run to failure" mode. No maintenance is done... just spend enough money to keep it running. This is not much different than HVAC systems.

Number 2 does cost more up for the initial install and continuing operation. These are usually systems where the people recognize the loss of cooling costs more in lost production time, than the cost of the maintenance.

Of course there are all sorts of arguments that can be made for this too. In general, I think Josip summed it up very nicely.

ingherrera
29-06-2006, 08:52 PM
thank you. In the PDF file, there is a PETRO CANADA oil, i have a tech data a it seems to work ulntil 15000 hr

Josip
29-06-2006, 09:22 PM
Hi,



Number 1 is usually a system that is designed to be cheap on the first install price. Then the system is operated in a "run to failure" mode. No maintenance is done... just spend enough money to keep it running. This is not much different than HVAC systems.

Number 2 does cost more up for the initial install and continuing operation. These are usually systems where the people recognize the loss of cooling costs more in lost production time, than the cost of the maintenance.

Of course there are all sorts of arguments that can be made for this too. In general, I think Josip summed it up very nicely.

I was thinking (couple of days before) to start a new thread with those opinions to ask you, what do you think : where are we today?

Best regards,

Josip :)

pbathe
04-01-2010, 06:05 AM
i want to use screw compressor instead of recip. i want to know -ve of screw compressors vs recip compressor OR benefits