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zacool
26-01-2015, 12:55 PM
i have a Bitzer HSN7471 screw compressor that is bursting the piping on the oil cooler of the system. has anyone ever had this before? there three systems on the site but only one is bursting.
i can not see anything obvious that would cause this.
any help with this would be appreciated.:confused

mbc
26-01-2015, 06:48 PM
what you mean of bursting ?
what type you used for oil cooling.

zacool
27-01-2015, 09:03 AM
hi there
the actual pipework from the oil separator to the air cooled oil cooler is bursting, it starts by bulging and eventually splits down one side of the pipework. the oil we are using is BH170 and the temperature of the oil line where it goes into the sump of the screw compressor is 63-65 degrees Celsius. there is a check valve on the oil line which is functioning correctly as well as the flow switch and solenoid valve. the overall temperatures on the affected screw are all lower than the other screws which are all functioning correctly and do not burst.

RANGER1
27-01-2015, 10:23 AM
Check valve, seems unusual, what's it's purpose?
If oil/refrigerant locked between solenoid & check valve expect possibility of exceptionally high pressures
whatever check valve is for I'm not sure, but it should be after solenoid, not before, if that's the case.
Oil cooler should also have a relief valve to protect it as well against over pressure.

zacool
27-01-2015, 12:40 PM
Check valve, seems unusual, what's it's purpose?
If oil/refrigerant locked between solenoid & check valve expect possibility of exceptionally high pressures
whatever check valve is for I'm not sure, but it should be after solenoid, not before, if that's the case.
Oil cooler should also have a relief valve to protect it as well against over pressure.

thanks
we have already started to reposition the solenoid valve to see if this will cure the problem.

mbc
27-01-2015, 04:25 PM
I did a lots work with Bitzer screw compressor as same as HSN & HSK with different types
Water cold and air cold also with ECO.
in oil line you should not have loop.
you should have from oil separator
1) valve
2)oil cooler
3)valve
4) oil filter
5)solenoid valve
6) flow switch
7) sight glass
8) valve
compressor
it is better you put 2 gags in inlet and outlet of filter
and also 3 way oil valve is by pass oil when it is cold

RANGER1
27-01-2015, 09:04 PM
thanks
we have already started to reposition the solenoid valve to see if this will cure the problem.

Zacool,
Can you advise us on position of all the components in oil line?
If you re-position solenoid maybe something else happens, especially with this mystery check valve.
Also refrigerant. what type of tube you are using & it's pressure rating.

zacool
29-01-2015, 01:11 PM
the components are as follows: oil separator,valve, check valve, filter, flow switch, solenoid.
the tubing used is from a major local manufacturer by the name of Maksel and we are using tubing rated for R410a. so tubing is not issue. this is specific to the one screw compressor condenser. the other compressor packs are fine. it must be something specific with the particular pack.

zacool
29-01-2015, 01:12 PM
I forgot to add the sight glass which is after the solenoid.

mbc
29-01-2015, 04:37 PM
you did wrong pipes works
if you see the bitzer documents there is no check valve in pipe line and also where is the position of oil cooler?
1) valve
2)oil cooler
3)valve
4) oil filter
5)solenoid valve
6) flow switch
7) sight glass
8) valve
compressor

Magoo
29-01-2015, 10:36 PM
The compressor discharge valve is a stop check as well, there will be a check valve on outlet of oil separator and a solenoid on oil feed into compressor. If oil cooler tubes are swelling and bursting then oil is trapped and hydraulicing the tubes, suggest the oil temp regulation 3 way valve (AMOT ) is installed incorrectly or jammed or faulty, as oil temp is too low entering compressor.
just a thought, magoo