Bock GEA 08810 Cylinder Head CR92 230V AC

The Bock / GEA 08810 is an engineered cast-iron cylinder head assembly equipped with an integrated CR92 capacity regulator (unloader assembly) and a 230V AC solenoid coil. Designed specifically for Bock F-series open-type reciprocating compressors (F14, F14/1366, FX14, F16, and FX16), this assembly regulates refrigeration capacity by blocking the suction intake of a cylinder bank via gas bypass.

When energised or de-energised through the plant automation/DCS, the CR92 solenoid pilot directs discharge and suction pressure differentials across the integrated unloader piston, lifting or seating the suction valve ring to step down compressor displacement (typically providing 50% or 75% staged steps depending on bank arrangement). This reduces thermal cycling, prevents low-suction evaporator freezing, and curbs peak electrical inrush on shipboard generator sets or industrial chiller feeds.

Technical Details:

Features

1. Direct Cylinder Unloading Mechanism: Utilises the CR92 electro-pneumatic gas bypass mechanism to unload designated cylinder pairs without requiring external VFDs.
2. Matched Hydraulic Tolerances: Precision-machined face profiles match the Bock 08498 dual-bank valve plate assembly and 08493 metal-elastomer composite gasket arrays.
3. Cast GG25 Iron Metallurgy: High-tensile grey cast iron body maintains structural integrity under cycling discharge gas pulses and thermal shocks up to 140°C.
4. Complete Drop-In Field Retrofit: Shipped as a complete set containing the cylinder head casting, CR92 pilot cartridge, solenoid valve body, 230V coil, and terminal plug.

Compatible Compressor Models

• Bock F-Series (Standard Refrigerants): F14, F14/1366, F16, F16/1751, F16/2058
• Bock FX-Series (Ester Oil / HFC Refrigerants): FX14, FX14/1366, FX16, FX16/1751, FX16/2058
• Open-Type Condensing Units: Bock FDK4, FDK14, FDK16 Marine Packaged Chiller Skids

Cross-Reference & Part Numbers

• GEA Bock Part Number: 08810
• Danfoss Global Part Code: 097B08810
• EAN / Barcode: 5715162581322
• Associated Mating Components:
  • Valve Plate Complete: 08498
  • Complete Gasket Set: 08493
  • Alternative Unloader Valve Cartridge Set: 08821
  • Solenoid Replacement Coil: 07213 (230V AC) / 07214 (24V DC optional)

Frequently Asked Questions

How does the Bock 08810 cylinder head with CR92 capacity regulator work?

The Bock 08810 assembly uses an integrated electro-pneumatic pilot valve (CR92) and a 230V AC solenoid coil to direct high-pressure discharge gas against an internal unloader piston. When energised, the unloader piston pushes down the suction reed valves of the cylinder bank, preventing compression and allowing refrigerant gas to cycle back without load, effectively reducing total compressor output.

Can the 08810 cylinder head be retrofitted to standard Bock F14 or F16 compressors?

Yes. The 08810 is a direct retrofit replacement for standard solid cylinder heads on Bock F14, FX14, F16, and FX16 models. You will need the compatible valve plate assembly (Bock 08498) and a 230V control signal from your plant PLC or thermostat step-controller.

What is the difference between legacy Bock 08810 and Danfoss 097B08810?

They are physically and functionally identical. Following Danfoss’s acquisition of GEA Bock, the legacy 5-digit part number 08810 was integrated into the Danfoss master parts catalogue under material code 097B08810. Both designations refer to the exact same German-manufactured assembly.

What are the symptoms of a failing CR92 capacity regulator on a Bock compressor?

Common failure symptoms include:

• Compressor running continuously without pulling down cold room temperature (solenoid stuck open / loaded cylinder bank failing to compress).
• Immediate high motor load and excessive current spikes during partial-load conditions (solenoid stuck closed / unable to unload).
• Loud metallic ticking or hammering within the cylinder head due to a fractured internal unloader piston return spring.

What is the correct tightening torque for the cylinder head bolts on Bock F16?

For M12 cylinder head bolts, torque sequentially in three diagonal passes to a final specification of 90–95 Nm. Never torque to final spec in a single pass, as this warps the head casting and leads to premature high-pressure gasket blow-by.