COMPRESSOR PROTECTIVE DEVICES
High Pressure Oil Management System
High Pressure Oil Management Systems remove the need for a separate Oil
Reservoir. This type of system also reduces the amount of pipework and
A High Pressure Oil Management System relies on the Oil Level Regulators
being able to operate with a high pressure differential. Mechanical Oil Level
Regulators cannot be used on this type of system. The Electronic Oil Level
Regulator (14) is recommended for this application. Electro-Mechanical
Regulators can also be used. A High Pressure Oil Management System is
not recommended for HCFC/mineral oil systems due to potential foaming
The common discharge is piped to the inlet of the Oil Separator-Reservoir
(13) and the outlet of the Separator-Reservoir is piped to the condenser.
The oil return connection, positioned at the bottom of the vessel,
is piped to the Oil Level Regulators. An Oil Filter (10) or Oil Filter-Drier (11)
should be installed between the Oil Separator-Reservoir and the Electronic
Oil Level Regulators (14).
It is recognized best practice to fit a solenoid valve, sight glass, and
shut-off valve in the oil return line. These components are not shown in the
Discharge Check Valve (4) should be fitted between the Separator and
Condenser to ensure condensed liquid refrigerant is not returned to the
The function of an Oil Separator is to remove oil from
the discharge gas and return it to the compressor, either directly or
indirectly. This helps maintain the compressor crankcase oil level and
raises the efficiency of the system by preventing excessive oil circulation.
Oil Separators are not 100% efficient, so installing an Oil Separator
should not be viewed as a replacement for oil traps, accumulators, or
good oil return piping practices. Henry Technologies’ manufactures two
different types of Oil Separators, Helical and Conventional.
Discharge Check Valve
The function of a Check Valve is to allow
fluid flow in one direction only. This prevents condensed liquid refrigerant
returning down the discharge line into the Separator. If this Check Valve
is not installed the Separator can feed excessive liquid refrigerant to the
Compressor on start up. This can cause oil dilution, excessive foaming,
erratic oil pressures and possible compressor damage. The Check Valve
must be installed after the Oil Separator, before the Condenser.
The function of an Oil Strainer is to remove system debris
from the refrigerant oil. Their purpose is to protect compressors and Oil
Level Regulators from damage. For recommendations on HFC/POE
systems, refer to section on oil filters and oil filter-driers.
Oil Return Line.
The function of an Oil Reservoir is to provide a holding
charge of oil, as part of a Low Pressure Oil Management System. The
amount of oil circulating in a system varies depending on the operating
conditions. The Oil Reservoir caters to these fluctuations by providing
additional storage capacity.
Mechanical Oil Level Regulators
The function of a Mechanical Oil
Level Regulator is to control the oil level in the compressor crankcase.
This protects the compressors from damage. There are two main types
of Oil Level Regulators, fixed level and adjustable level. The fixed level
regulators have an allowable oil pressure differential range of 5 to 30 PSI
(0.35 to 2.1 Bar). The adjustable level regulators have an allowable oil
pressure differential range of 5 to 90 PSI (0.35 to 6.2 Bar). Oil pressure
differential is the difference between the crankcase pressure and the
pressure in the Oil Reservoir. Gravity pressure head should be included
also, if applicable. Some regulator models are fitted with an equalization
connection that enables the oil levels between several compressors to
The function of an Oil Filter is to remove system debris
from the refrigerant oil. An Oil Filter is recommended for HFC/POE
systems instead of individual Oil Strainers, where filtration only is
The function of an Oil Filter-Drier is to remove both
system debris and moisture from the refrigerant oil. An Oil Filter-Drier is
recommended for HFC/POE systems instead of individual Oil Strainers,
where both filtration and moisture removal is required.
Reservoir Pressure Valve
The function of a Reservoir Pressure
Valve is to maintain a positive pressure in the Oil Reservoir above the
compressor crankcase pressure. Two different pressure settings are
available; 5 psi (0.34 Bar) and 20 psi (1.38 Bar). A higher pressure
differential will increase the oil flow rate from the oil reservoir back to the
compressors. The pressure setting should be selected taking into
account the allowable oil pressure differential of the Oil Level Regulator
The function of an Oil Separator-Reservoir
is to provide a Oil Separator and Oil Reservoir in one unit. It is designed
for High Pressure Oil Management Systems and used with Electro-
Mechanical or Electronic Regulators.
Electronic Oil Level Regulator
The function of the Electronic Oil
Level Regulator is to control the oil level in the Compressor crankcase.
This protects the Compressors from damage. This regulator can be used
on Low or High Pressure Oil Management Systems.
Refer to equipment list for further details on each
component in the oil system
HIGH PRESSURE OIL MANAGEMENT SYSTEM
EQUIPMENT LIST FOR OIL LEVEL CONTROL