Marine Freezer Plant

[Globe76]

Okay, just been woken up by an alarm for high freezer temp onboard. I am engineer on yacht so am not expert in these matters but have a okay understanding on how most things work onboard.

I have a Dorin Compressor. Sea Water cooled condensors.

It reset the compressor at the breaker and it runs for about 10-15 minutes then cuts out, there is a Danfoss Pressure Switch that I am sure is controlling the cut in and cut out pressures on Low and High Sides.

With compressor running the L.P Side seems to be running a little higher than usual as there are markings on pressure guages for the lower and higher limits, the Low Pressure side seems to be high.
The High Pressure side seems to be midway in the setpoints as marked off on the pressure guages.

So the H.P and L.P side are running higher than they should be.

I could get figure for you in a few minutes.

Just hoping I can start troubleshooting this A.S.A.P as it is in middle of night here and I have to keep the freezers cold as there is lots of frozen goods onboard.

Could it be dirty/fouled condensor coils on the Sea Water Side???

[Globe76]

Okay here are some figures

On the Pressure Gauges the previous engineer has made markings on pressure Gauge for High and Low set points for both the H.P and L.P side.

On the Gauge for H.P the two set point markings on pressure gauge are 180-240 when I reset the breaker and compressor kicks in...it runs at around 240 which is in the middle of the high and low optimum markings.

On the Gauge for L.P the two set point markings on the pressure gauge are 20-40 and this is running at 60 when I reset compressor breaker so looks like it is running to high.

The presure gauges are in HgVac and Lb/In

So it seems like the Low Pressure side is running to High, is this a condensor issue, sea water cooled condensors?

I also noticed a few drops from one of the pressure gauges, put my finger in it and seems like oily residue, not much maybe a couple drips worth.

I have another compressor directy next to is which is for all our fridges and it seems to be running fine?

Could it be a dodgy pressure switch???

Please help, its 2am here now and I hope to sort it out so I can sleep and keep frozen good frozen

[Gingerair]

Hi Globe 76

When you say it cuts out do you mean it trips the breaker, an overload, or on another safety switch ??

The warmer the freezer is the higher the suction pressure will be, what gas is it on ?
Has the system got a liquid line sightglass, when the plant runs is it flashing or clear ?
240psi is quite high for a water cooled condenser, check what the HP switch is set at.
If it's running with high discharge pressures for a long time this could cause the motor to trip, sea water condensers have a habit of fowling so if the gas charge is ok this is a distinct possibility..
Also check the sea water flow through the condenser is ok & if its got a water pressure reg valve check thats also working..

I've gotta hit my scratcher now, good luck..
Hope there's someone else on here to help..

Ginge :)

[Globe76]

The breaker does not trip, but the Compressor stops running and the Contacter still looks energised with a red led. I am going to reset again now.

Gas is 404A
Yes there is a sight glass and when compressor running it is at similar level as the Fridge Plant Compressor. Its does seem a little bubbly, but still showing lots of Refrigerant in Sight Glass.

Sea Water flow seems to be okay as there is sight glass showing this go overboard.

The Pressure Switch setpoints are as follows....

Cut In 10PSI
Diferential - 15PSI
Cut Out - 350 PSI

Just went and checked again the Compressor was not running, the High Pressure was at 200 which was within limits and the L.P was 80PSI which is way above normal.

I reset the break and the compressor starts to run, but only for about 1 minutes at a time at the pressures mentioned before.

Please help!