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11. DUAL ORIFICE
The interchangeable Orifice Distributor is an improvement on the standard flange mounted type in that:
•
Each distributor is fitted with a dual orifice assembly.
•
Each distributor has a screwed cap to facilitate orifice selection.
•
Each distributor has a Schraeder valve to facilitate pressure testing during operation.
System performance
The performance of any system fitted with this type of distributor, can still be influenced by the TEV. When selecting a
TEV, allow for the following distributor system pressure drop.
For R134a 2 bar
For R404A,R407A/B/C,R507A 3 bar
IMPORTANT!
When removing or replacing the distributor screwed cap, do not place excessive strain upon the distrib-
utor leads.
If, when the coil is operating at or close to its design temperature, the TD is above normal, that is to say, the difference
between the air entering the coil and the evaporating temperature is too great (e.g. the evaporating temperature is
low), check the TEV superheat. If it is above 0.9 TD and will not respond to adjustment, it is possible that the distributor
pressure is excessive.
Dual Orifice
WARNING!
Goggles must be worn when using the test connection as there may be
liquid refrigerant in the distributor body cavity.
WARNING!
Before removing the distributor cap ensure that all liquid
refrigerant has been evacuated from this point by carefully
pumping the system down