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REFRIGERANT LINE CHECK VALVES
Check Valves
Dunan's check valves are engineered to ensure reliable one-way refrigerant flow, preventing backflow that can damage critical components and disrupt system performance. Built with durability in mind, these valves are ideal for both commercial and industrial HVACR applications, handling high pressures and a wide range of refrigerants with ease.
Whether you're upgrading your system or planning a new installation, Dunan’s check valves are a key component for maintaining efficiency and protecting your investment.
For Automatic Control of Flow Direction without Manual Intervention
If your system requires automatic control of flow direction without manual intervention, a check valve is an excellent choice. They are particularly important in systems with multiple circuits or reversing functions, such as heat pumps, where flow reversal can cause serious operational issues. However, if your primary need is flow regulation or isolation, our other components like solenoid valves, ball valves, or thermostatic expansion valves might be more appropriate.
Completely Automatic
FDM valves require no manual or electrical input.
Compact & Cost Effective
Ideal for applications where space and simplicity are priorities.
System Protection
Check valves prevent reverse flow without the need for complex controls.
Alternatives
If precise control over refrigerant flow or remote operation is required, alternatives such as solenoid valves (for automated on/off control) might be better suited to your application.
FDM Series
The FDM series of check valves use magnetic diaphragm design and feature a metal sealing structure, built-in guiding device, and self-closing structure, allowing installation angles in all directions without any limit.
Operating Temperatures
Medium Temperature: -30°C~+120°C
Applicable Refrigerants
R134a, R407C, R410A, R404A, and R290
FDM Series
| Model | Connection | Max. Operating Pressure | Pressure Drop Across Valve | Kv |
| (In) | (MPa) | △P(MPa) | (m3/h) | |
| FFDM1006-0001 | 1/4 | 5 | 10.01 | 0.65 |
| FDM1010-0001 | 3/8 | 5 | 0.01 | 1.29 |
| FDM1613-0001 | 1/2 | 5 | 0.01 | 2.49 |
| FDM1616-0001 | 5/8 | 5 | 0.01 | 2.83 |
| FDM1619-0001 | 3/4 | 4.5 | 0.01 | 3.17 |
| FDM1622-0001 | 7/8 | 4.5 | 0.01 | 3.51 |
| FDM1822-0001 | 7/8 | 4.5 | 0.01 | 3.77 |
| FDM2519-0001 | 3/4 | 4.5 | 0.02 | 4.54 |
| FDM2522-0001 | 7/8 | 4.5 | 0.02 | 7.2 |
| FDM2529-0001 | 9/8 | 4.5 | 0.02 | 13.11 |
| FDM3229-0001 | 9/8 | 4.5 | 0.02 | 14.48 |
| FDM3835-0001 | 11/8 | 3.5 | 0.02 | 19.02 |
| FDM4842-0001 | 13/8 | 3.5 | 0.03 | 31.96 |
| FDM5754-0001 | 17/8 | 3.5 | 0.05 | 56.04 |
| FDM6567-0001 | 21/8 | 3.5 | 0.05 | 65.04 |
| FDM6580-0001 | 25/8 | 3.5 | 0.05 | 74.98 |
FDH Series
The FDH series of check valves with built-in piston ensure only correct flow direction and are equipped with a damping spring applicable to compressor discharge pipes in single or multi compressor systems.
Applicable Refrigerants
R134a, R407C, R410A, R404A, R290, and R32
Operating Pressure
Max. Operating Pressure: 4.9 MPa
Operating Temperature
Medium Temperature: -40°C~+150°
FDH Series
| Model | Max. Operating Pressure | Pressure Drop Across Valve | Kv |
| (MPa) | △P(MPa) | (m3/h) | |
| FFDH1013-0001 | 4.6 | 0.005 | 2.06 |
| FDH1316-0001 | 4.6 | 0.005 | 3.60 |
| FDH1619-0001 | 4.6 | 0.005 | 5.48 |
CV Series
CV series check valves feature a built-in piston and reinforced damping spring. They can be used in liquid, suction and hot gas lines in commercial refrigeration system and air conditioning systems.
Applicable Refrigerants
R134a, R407C, R410A, R404A, and R290 and R32
Operating Pressure
Max. Operating Pressure: 4.9 MPa
Operating Temperature
Medium Temperature: -40°C~+150°
CV Series
| Model | Kv | Min.OPD |
| (m3/h) | (bar) | |
| CV12S | 2.05 | 0.05 |
| CV16S | 3.0 | 0.05 |
| CV19S | 5.5 | 0.05 |
Kv(2