Danfoss KDC/GVD Pressure Control Valve Installation Guide
This guide provides instructions for the installation of Danfoss KDC/GVD pressure control valves, sizes 65 - 200 (2½ - 8 in.).
Refrigerants
These valves are applicable to HCFC, HFC, R717 (Ammonia), and R744 (CO2). Flammable hydrocarbons are not recommended. The valve is recommended for use only in closed circuits. For further information, please contact Danfoss.
Temperature and Pressure Ranges
- Temperature Range (KDC/GVD): -50/+150 °C (-58/+302 °F).
- Pressure Range: The valves are designed for a maximum working pressure of 40 bar (580 psig).
Installation
General Installation Requirements (Fig. 1)
The valve must be installed with the spindle vertically upwards. The valve is designed to withstand high internal pressure. However, the piping system should be designed to avoid liquid traps and reduce the risk of hydraulic pressure caused by thermal expansion. Ensure the valve is protected from pressure transients such as "liquid hammer" in the system.
Fig. 1: Correct and incorrect valve orientations.
Flow Direction (Fig. 3)
Important: The flow direction must be from the cone side towards the branch.
Fig. 3: Correct flow direction indicated by an arrow.
Welding (Fig. 4)
Before welding, remove the actuator to prevent damage to the gasket between the valve body and bonnet, and the Teflon gasket in the valve seat. Only use materials and welding methods compatible with the valve housing material. After welding, clean the valve internally to remove welding debris before reassembly. Avoid welding debris and dirt in the threads of the housing and bonnet. The valve housing must be free from stresses (external loads) after installation.
KDC/GVD valves must not be mounted in systems where the outlet side of the valve is open to the atmosphere. The outlet side must always be connected to the system or properly capped off, for example, with a welded-on end plate.
Fig. 4: Illustration showing actuator removal for welding.
Assembly (Fig. 5)
Remove welding debris and any dirt from pipes and the valve body before assembly. After mounting the bonnet and tightening the bonnet bolts, remove the disassembly bolt (pos. 32). This bolt secures the insert from falling out during disassembly and prevents damage to the Teflon seat when the bonnet is mounted.
Note! Always pull the valve seat back into the open position before assembling the valve.
For a pilot line, use DN10 steel pipe. Connection can be made directly to the valve using the NPT ¼" thread or via an adapter for a cutting ring.
Fig. 5: Assembly steps including bolt removal and pilot line connection.
Tightening (Fig. 5)
Tighten the bonnet with a torque wrench to the values indicated in the table.
| DN | Nm | LB-feet |
|---|---|---|
| DN 65 | 75 | 53 |
| DN 80 | 44 | 32 |
| DN 100 | 75 | 53 |
| DN 125-150 | 183 | 135 |
| DN 200 | 370 | 272 |
Colours and Identification
KDC/GVD valves are factory-painted with a red oxide primer. Valve identification is confirmed by the ID ring on top of the bonnet and stamping on the valve body. Prevent the external surface of the valve housing against corrosion with a suitable protective coating after installation and assembly. It is recommended to protect the ID ring when repainting the valve.
Maintenance
Dismantling the Valve (Fig. 4 and Fig. 5)
Do not remove the bonnet while the valve is still under pressure.
Evacuate the pipe system where the valve is installed. Ensure refrigerant is evacuated from both the inlet and outlet sides of the valve. Use the service port (pos. 15) on the valve to evacuate refrigerant from above the cone.
Mount the dismantling bolt (pos. 32), hexagon flange nut (pos. 31), and nylon ring (pos. 30) as shown in Fig. 5. Tighten the nut (pos. 31) a few rounds to draw the valve cone from the seat. Remove the bolts and then the valve top (actuator).
- Check that the O-ring has not been damaged.
- Check that the Teflon seat is free of scratches and impact marks.
Assembly (Fig. 5)
Remove welding debris and any dirt from pipes and the valve body before assembly. Mount the hexagon screw (pos. 32), hexagon flange nut (pos. 31), and nylon ring (pos. 30) as shown in Fig. 5. Tighten the nut (pos. 31) a few rounds to draw the valve cone from the seat. Remove the disassembly bolt after mounting the bonnet and tightening the bonnet bolts. The purpose of the bolt is to secure the insert from falling out during disassembly and to prevent damage to the Teflon seat when the bonnet is mounted.
Note! Always pull the valve seat back into the open position before assembling the valve.
