Calculating refrigerant charge

[Consultant]

Can someone help me to calculate the approx refrigerent charge ( kg) in a chiller

I have a Mercury Climate chiller that has four danfoss SZ185-4 Maneurop compressors running on R407C. Each compressor is rated at 52kW cooling capacity. Evap temp is 7.2 deg C, condensing temp is 54.4 deg C.
The suction press is 4 bar and the high press set at 20 bar.
Should the charge be around 13kg per compressor. Two circuits of two compressors eqaulling 26kg each?
Thanks

[Argus]

The total charge should be on the name plate if it?s a package unit, but here are a number of variables that will determine the final working charge.

It?s risky to use a rule of thumb because of the variations in coil and heat exchanger design from manufacturer to manufacturer. By the sound of it 13kg is a bit light to me, but you can?t be sure.
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CBR1000RR

[chemi-cool]

When there is no receiver, the charge is lower.
When in doubt, consult the manufacturer.

That will also give you someone to blame if something goes wrong.

Chemi