Blast freezer temperature problem. Please help!!!

I have a blast freezer with Bitzer S6F-30.2Y compressor. It normally goes down to -35c with 1.2 ton of fish in 8 hours. After service by an unqualified technician, it now takes 14 hours to reach -14c.
Parameters are:
18.5Amp
Discharge=224psi
Suction=8psi
Intermediate Pressure=89psi
Superheat bulb temp=34.7c
Oil pressure=94psi
I also have a little ice on the suction cup at the entrance to the cylinder, but not on the cylinder head.

I need help getting the system back to normal. Do I need to adjust the superheat or is it something else?
Any help will be appreciated. Thanks.

Hi Volta:)
you seem to know more than the average owner;)
Not a fridge guy in disguise:D

If your bulb temperature you refer to is the bulb for the evaporator your plant has 60k super heat, should be say 20k at the compressor inlet, depending on the suction pipe length.

Why not get the guy who installed it back to put it right, or have you not paid him:mad:


Evaporator is being starved of refrigerant, short of gas, blockage somewhere or incorrectly set expansion valve.

Kind Regards. Andy.:)

Thanks Andy,
The bulb I was referring to is the superheat bulb.
We just reloaded the system with 124kg of R507, which is the correct amount for this system.
I already changed the evaporator TXV with a new one with the same orifice.

I still have the same problem. Any ideas?

I can't get a real qualified tech since my equipment is in Africa.

Quote:

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Originally Posted by volta

I can't get a real qualified tech since my equipment is in Africa.

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Oh my god, oh my god, Marc !! Marc ,Maaaarrrrrccc!!!!! oh my god ,i can't believe you just said that,oh my god....MAAAAAAAARRRRRRRRRCCCCCCCC!!!!

cheers

richard

Don't panic Rich, it'll be OK.

Quote:

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Originally Posted by volta

I have a blast freezer with Bitzer S6F-30.2Y compressor. It normally goes down to -35c with 1.2 ton of fish in 8 hours. After service by an unqualified technician, it now takes 14 hours to reach -14c.
Parameters are:
18.5Amp
Discharge=224psi
Suction=8psi
Intermediate Pressure=89psi
Superheat bulb temp=34.7c
Oil pressure=94psi
I also have a little ice on the suction cup at the entrance to the cylinder, but not on the cylinder head.

I need help getting the system back to normal. Do I need to adjust the superheat or is it something else?
Any help will be appreciated. Thanks.

---

dear

to adjust tev ,,you must check the p-t chart of gas 507
you can find this chart at:
www.refrigerants.com/pics/ptchart.pdf

if you need a blast temp. -35 , the evaporator temp. will be -38 , and with 5 dgree superheat it will match -33
this temp. match pressur 10 psi
so you must increase the orifice of tev by rotate it clock wise untill you get 10 psi suction pressure

an other reason you check is:
may be the evaporator coil may be dirty,,alot of impurities stucking on its surface,,so it must be cleaned away ,
thats all i have to tell you
good luck
afeef:)

Quote:

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I can't get a real qualified tech since my equipment is in Africa

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is that because they are all in england moaning about the ineptitude of the population?


and 18.5 amp ?? what is that? if its the comp. running current the it sounds very low for the plant. suspect poor duty due to some kind of restriction if you are sure the charge is correct.

Quote:

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Originally Posted by volta

I already changed the evaporator TXV with a new one with the same orifice.

I still have the same problem. Any ideas?

.

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Volta we will assume you are not Marc, if you are, I will do something un speakable to you, involving your knee caps, happens often over here.:D :D


Did you set the TXV superheat, open the valve adjust screw out until the superheat lowers to 10k at evaporator outlet, you may then proceed to play with it until you get a 4.5k superheat, but I wouldn't bother.

Fit a pressure gauge and a thermometer probe at the evaporator outlet. Read off the saturation pressure and convert to degrees c for the refrigerant used. Then adjust the valve until the probe reads within 10K of the pressure reading in Deg C.

Then retire to the pub and tell your mates about it---------- or not as the case may be:)
Kind Regards, Andy:)

Quote:

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Originally Posted by volta

I have a blast freezer with Bitzer S6F-30.2Y compressor. It normally goes down to -35c with 1.2 ton of fish in 8 hours. After service by an unqualified technician, it now takes 14 hours to reach -14c.
Parameters are:
18.5Amp
Discharge=224psi
Suction=8psi
Intermediate Pressure=89psi
Superheat bulb temp=34.7c
Oil pressure=94psi
I also have a little ice on the suction cup at the entrance to the cylinder, but not on the cylinder head.

I need help getting the system back to normal. Do I need to adjust the superheat or is it something else?
Any help will be appreciated. Thanks.

---

Intermediate pressure high:confused:

and thus the oil pressure:eek:

Bulb temp is the desuperheating bulb for the interstage, the valve has been opened up too much

Kind Regards. Andy:)

Hi:)

Discharge low:confused:

amps low:confused:

what about the head joint, two stage bitzers would blow the odd one.

Please fit new head joint and set desuperheat TEV;)

am in africa and you can reach me on
griffine.ongaro@yahoo.com
ive installed more than five blast freezer around red sea and they are ok,just book aflight ill sort it out for you
thanks

Quote:

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Originally Posted by otieno

am in africa and you can reach me on
griffine.ongaro@yahoo.com
ive installed more than five blast freezer around red sea and they are ok,just book aflight ill sort it out for you
thanks

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But four years too late. ;)

Quote:

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Originally Posted by Brian_UK

But four years too late. ;)

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Ha~~~, so funny
But, Maybe Volta still need any help in Africa

Hi there,

I assume your TEV is MOP type.

The head of TEV must be few degrees warmer than the bulb, if not the valve will close.
What I do in this applications is this : use wire type heaters, like the one used in drain pipes, connect this heater on top of the TEV and insulate it. the rest must be in the air, because every one meter of this heaters must be connected to electricity. Energize this heater when compressor is on.
The other issue you have to consider is the amount of sub-cooling. If you have sub-cooler, which you must, then you will get around 40°C sub-cooling. Select correct size of TEV orifice according to that sub-cooling. If not then your suction will be higher than it should be.

Cheers