Dorin H-type compressors for AC application

[marinecool]

I have seen a considerable number of piston road failures on the Dorin H-type compressors, mainly on the 6 and 8 cylinder size compressors.
Typical failure is in the large end bearing, seems to have been pulled apart. No indication of liquid slugging no damage to valve plates or other indications.
The compressors are used for AC application running at 60Hz with R404a.
Any one experienced similar problem?
Any suggestion to the cause?

[nike123]

Why is R404a used in AC aplication?

[Magoo]

Do the compressors have oil coolers and head cooling fans, plus check the oil viscosity is correct for application

[marinecool]

The reason for choosing R404a is mainly due to costumer’s request, this way they only need to keep one type of refrigerant on the ship. The provision pant (low temp) and the AC plant are then both designed for R404a.
Regarding head cooling fans, used only when required according to Dorin specification.
As you know Dorin have changed from the Y-type to the H-type on the larger 6-8 cylinder compressors, one of the changes was the valves. Y-comp used ring valve reeds – the new H-type uses the stronger designed finger valves, at the same time the piston rod dimension was made smaller on the H-type. The weak point now being the piston rod – interesting enough the piston rods are what I find failing.