Q: What type of filter-drier is recommended for cleaning a system after a compressor motor burn?
After a burn, both the liquid and suction line cores (if provided) should be replaced with special ‘burnout blocks.’ These cores have an ‘HH’ in their model nomenclature. The system is then operated with these cores in place until the refrigerant and oil are clean and free of acids. Once this condition is attained, the liquid core must be replaced with a standard type core (UK48 or H48). The suction core should also be replaced with an F-48 filter.

Q: My system does not have a removable suction core and there isn’t enough space to install one. What should I do?
On smaller self-contained systems, where a removable suction core cannot be installed, you should put in a hermetic type suction line fi lter-drier (ASK-HH). This must
only be left in the system until the refrigerant and oil have been cleaned and then either be removed or replaced with a new one so as to prevent excessive pressure drop.

Q: How do I know when the suction core needs to be replaced?
A wet indication in the sight glass or a pressure differential greater than the equipment manufacturer’s recommendation dictates the need for replacement. If the equipment manufacturer’s recommendation is not available, the following maximum pressure drops are suggested:
MAXIMUM RECOMMENDED SUCTIION LINE FILTERDRIER PRESSURE DROP (PSI)

(REFER IMAGE)

The pressure drops indicated in the columns titled ‘TEMPORARY INSTALLATIONS’ should only be used during the clean-up operation as an indication when the core
needs to be replaced. During normal operation, the pressure drop should not exceed those shown in the column ‘PERMANENT INSTALLATION.’ Operating with high
pressure drop across a suction filter-drier will decrease system efficiency and must be avoided.