Grizzly
06-09-2008, 11:25 PM
We all know that the fastest way to add refrigerant
is to add it in liquid form.
And the many ways of achieving this have and are, being discussed on this forum.
But I have never seen mentioned the point that in some circumstances.
Initial charging with Liquid Refrigerant, even on the high side can cause extensive damage.
EG.
If you have a water cooled shell and tube condenser or evaporator.
ALLWAYS INITIALLY CHARGE WITH VAPOUR!!
Bringing the system up to it's refrigerants temperature / pressure of around or preferably just above freezing.
Because if you have a system with a poor water / glycol flow.
There could be insufficient heat load around the internal copper tubes.
And adding liquid Refrigerant can cause Ice Crystals to form around the tubes and crush them.
This not fiction I have seen it done.
In fairness it was a Frigate in dry dock, where one of the chillers had major repairs which involved removing the refrigerant.
This was then re-added upon completion of the repairs.
Sadly the Engineers concerned had forgotten the fact that the condenser cooling medium was Sea Water.
As the ship was in dry dock being refitted there was no sea water available to in this case to absorb the negative temperatures being applied!
The End result was a very costly Condenser change.
This could just of easily happened if say you had poor water flow and the flow switch was still made.
If you charge from scratch through the Evap, then the same could happen there.
So the simple answer is charge with vapour (or liquid that is flashed off whilst it enters the system)
Until your system has reached that refrigerants
pressure / temperature for just above freezing!
Sorry it's so long winded Guy's, but I couldn't think of a shorter way of explaining what I mean!
Hopefully someone will benefit from this snippet?
Cheers Grizzly
is to add it in liquid form.
And the many ways of achieving this have and are, being discussed on this forum.
But I have never seen mentioned the point that in some circumstances.
Initial charging with Liquid Refrigerant, even on the high side can cause extensive damage.
EG.
If you have a water cooled shell and tube condenser or evaporator.
ALLWAYS INITIALLY CHARGE WITH VAPOUR!!
Bringing the system up to it's refrigerants temperature / pressure of around or preferably just above freezing.
Because if you have a system with a poor water / glycol flow.
There could be insufficient heat load around the internal copper tubes.
And adding liquid Refrigerant can cause Ice Crystals to form around the tubes and crush them.
This not fiction I have seen it done.
In fairness it was a Frigate in dry dock, where one of the chillers had major repairs which involved removing the refrigerant.
This was then re-added upon completion of the repairs.
Sadly the Engineers concerned had forgotten the fact that the condenser cooling medium was Sea Water.
As the ship was in dry dock being refitted there was no sea water available to in this case to absorb the negative temperatures being applied!
The End result was a very costly Condenser change.
This could just of easily happened if say you had poor water flow and the flow switch was still made.
If you charge from scratch through the Evap, then the same could happen there.
So the simple answer is charge with vapour (or liquid that is flashed off whilst it enters the system)
Until your system has reached that refrigerants
pressure / temperature for just above freezing!
Sorry it's so long winded Guy's, but I couldn't think of a shorter way of explaining what I mean!
Hopefully someone will benefit from this snippet?
Cheers Grizzly