r404a Ice machine flooding

[nandoanalog]

Hi, I have an ice machine that's behaving weird on me. I'm letting the crank heater preheat the compressor for a few hours until it's warm. Every time I start it, I see some white foam on the oil level looking glass. The whole compressor starts freezing within a minute or two of start-up, and then it shuts off giving me the "oil pressure protection" error. If I restart it immediately, the compressor makes a clacking sound for half a second (flooded start?), and it wont shut down again.
Refrigerant pressure seems to be fine. 0.1 to 0.2 mpa on low pressure, 0.4 to 0.6 mpa oil pressure, and high pressure 2 mpa.

Any ideas on what's causing this? Shall I post pictures?

[nike123]

Is there pump down cycle incorporated or suction accumulator.
Do you have refrigerant cycle diagram?

What type of expansion device you have?

It looks like there is no superheat control and/or migration of refrigerant in compressor case at standstill.

[nandoanalog]

I don't have any idea of what I got here. I'll ask the manufacturer for a refrigerant cycle diagram. Btw, can this be caused by a bad setting ?

[nike123]

If you have electronic expansion valve, than answer is that is likely possible! Even with mechanical expansion valve if it is not correctly adjusted or its oriffice is wrongly selected.

I doubt that you have capillary tube expansion device since you have sight glass at compressor, which tells me that compressor is of larger size.
With capillary tube, there is no chance that superheat is low if unit is not overcharged.

But, that is lot of guessing. Give us details like manufacturer and model No. and measurement results of pressures and temperatures at usual points if you are able to run unit in stable conditions after initial problems with liquid flooding.
(suction and discharge pressure, liquid line before expansion device temperature, suction line after evaporator temperature, suction line before compressor, discharge line, water entering temperature, ambient air temperature, condenser leaving air temperature, etc....)

Check amperage draw of crancase heater. Check that crancase heater is energised always when compressor is at stand by (off cycle).
After prolonged time (few hours or more) of power off state of entire machine, crankcase heater should be energised for at least 8 hours (or more depending on ambient temperature) before starting compressor for first time, if surrounding temperature where compressor is placed is below 15°C.

For larger systems which have more gas in kg than compressor manufacturer prescript as max. charge and without suction accumulator, pump-down should be mandatory.

[shaaf]

Dear Better you throttle fully your suction stop valve . open slowly valve.
Leave manufacturer better you solve it yourself.

[nandoanalog]

Still couldn't get a hold of the manufacturer. Maybe this can give you guys an idea... Sorry for the quality though.

https://www.youtube.com/watch?v=f9TqAoZKStU

20140918_143913.jpg20140918_144212.jpg20140918_144244.jpg20140918_144311.jpg20140918_144320.jpg

[nandoanalog]

20140918_144326.jpg20140918_144358.jpg20140918_144500.jpg20140918_144533.jpg20140918_144551.jpg

[nandoanalog]

20140918_144641.jpg Hope this helps...

[nike123]

This icemaker definitely need pump down cycle.

[nandoanalog]

A guy told me to disconnect the solenoid in this picture for an hour or so when I start the machine. I haven't tried it yet because he didn't tell me what it does. I'm afraid of breaking the compressor....20140918_144533.jpg

[nike123]

Solenoid for pump-down should be at pipe just before T piece leading to that two expansion valves.
Solenoid on that picture is liquid injection solenoid for cooling of compressor, and if it is always open, and there is no expansion device before entering to suction pipe, you can have excess liquid and liquid hummers as you experiencing.

Close that isolation ball valve before solenoid and later open it slightly until you get satisfactory discharge line temperature (about 75°-90°C )at steady operation.

Check that that solenoid is de-energized when compressor is at standstill.

Then, mark ball valve position and place cap at its place.

[nandoanalog]

I messed with the ball valve, but I'm not sure of what I did. It was fully turned anti clockwise, so I turned it clockwise all the way (hopefully closing it). Started the machine, and the machine made a hissing sound like it was trying to suck on something. Loosen it back just a smudge until the sound was gone, and foam started showing up in the oil glass. Closed it again, and the foam was gone. But the whole compressor started freezing... Opened it up, and the ice started melting.
The machine did not shut down, and seems to be running stable. Am I supposed to do this kind of procedure every time?

[nike123]

I think you should stop messing with that machine since damage could be to expensive for you. That need attention of engineer who is familiar with machine. You should watch and learn from him.
Without details about circuit, it is not advisable to proceed with this kind of giving any directions on blind.

[nandoanalog]

I think you should stop messing with that machine since damage could be to expensive for you. That need attention of engineer who is familiar with machine. You should watch and learn from him.
Without details about circuit, it is not advisable to proceed with this kind of giving any directions on blind.

The engineer is chinese, and does not speak english... They sent me the electric diagram of the machine, but don't have a drawing of the refrigerant cycle. I'm not sure if there's anything to learn from him

[nike123]

Than you should do refrigerant diagram by yourself and post it here!

Check that that solenoid is de-energized when compressor is at standstill.

What about this check?

[nandoanalog]

Than you should do refrigerant diagram by yourself and post it here!



What about this check?

I don't know how to draw a diagram. I can try, but it probably wont be good enough. It looks like every "pump down cycle" diagram I can find on google images.

The solenoid isn't energized. But it opens way too soon on start up. Then the oil starts foaming badly, the compressor freezes almost entirely, and soon there isn't any oil in the looking glass. And it shuts down.

There's a valve before the solenoid. And if I start the machine with that valve almost closed, allowing the compressor to warm up, then slowly open the valve, everything seems to work fine. No foam, no weird noises, nothing.

[nike123]

I don't know how to draw a diagram.
I can try, but it probably wont be good enough. It looks like every "pump down cycle" diagram I can find on Google images.

That solenoid on posted pictures is definitively not Pump-Down solenoid!


Regarding drawing! Easy! Start with drawing main components in circle same in order as refrigerant flow is passing thru them (compressor=> condenser =>TXV => evaporator => etc...), and then follow lines in your system and draw everything as it is actually on your system.
It is probably best to not use samples from Google since they can mislead you to draw what is not actually there. Only use samples for copying appearance of correct symbols of components.

The solenoid isn't energized. But it opens way too soon on start up. Then the oil starts foaming badly, the compressor freezes almost entirely, and soon there isn't any oil in the looking glass. And it shuts down.

There's a valve before the solenoid. And if I start the machine with that valve almost closed, allowing the compressor to warm up, then slowly open the valve, everything seems to work fine. No foam, no weird noises, nothing.

Maybe quick solution there is to add thermostat at discharge line which will cut supply to liquid cooling solenoid valve until discharge line reach 85-90°C temperature (or whatever compressor manufacturer recommends).

[aabbcc]

. Every time I start it, I see some white foam on the oil level looking glass.

I actually DO NOT LIKE the white foam in the oil glass... When have foamy or milky oils means water or moisture in the oils... The clank noise... Hmmmm!! I think is not good as well.

If so you have a loooot of work to do it right...

Last years huge amount of Chinese refrigerants used to service / maintain ...
As fake certificates are all around.. Had a result of burned compressors ...