Bock / GEA FX16/1751 Semi-Hermetic Compressor

Bock / GEA FX16/1751 Semi-Hermetic Reciprocating Compressor

The Bock / GEA FX16/1751 is a semi-hermetic reciprocating refrigeration compressor engineered for marine provisions, offshore accommodation HVAC, and heavy-duty cold-chain duties. Configured with an “FX” designation, this model features factory ester oil (POE) lubrication specifically engineered for compatibility with hydrofluorocarbon (HFC) and low-GWP refrigerants including R404A, R507, R407C, and R134a.

Hydraulic oil pressure differential monitoring, 28 bar high-side leak testing, dynamic valve-plate sealing verification under full compression ratio, and electrical winding insulation testing (Megger minimum 100 MΩ at 500 V DC).

Model Details:

• Manufacturer: Bock Kältemaschinen GmbH / GEA Refrigeration Technologies
• Model Series: HG16 / F16 / FX16 (4-Cylinder Generation)
• Model Code: FX16/1751
• Displacement / Swept Volume: 152.2 m³/h at 1450 RPM (50 Hz) / 183.6 m³/h at 1740 RPM (60 Hz)
• Manufacturer Part Numbers (MPN): 097B1751, FX16-1751-A, FX16/1751-4

Performance Features

1. Hydrodynamic Forced-Feed Lubrication: Integrated bi-directional gear pump delivers continuous oil distribution regardless of shaft rotation direction, complete with differential oil pressure switch connection ports.
2. Optimized Valve Plate Geometries: Impact-resistant Swedish flapper spring steel reed valves minimize dead clearance volume, optimizing volumetric efficiency across extreme low-temperature and air-conditioning compression ratios.
3. Thermal Motor Protection: Internal PTC sensor chain integrated into the winding overhang, interfacing directly with standard Kriwan monitoring units (INT69 / INT69 G) for locked-rotor and phase-failure cutoff.
4. Dual-Voltage Part-Winding or Across-the-Line Starting: 400V/460V direct-on-line (DOL) or 50%/50% part-winding (PW) terminal block configuration reduces inrush current spikes on marine generator plants.
5. Service-Friendly Crankcase Design: Generous oil inspection sight glass, standard Schrader charging connections, crankcase heater sleeve pocket, and dual-suction service shut-off ports simplify dockside overhaul and routine maintenance.

Technical Specifications

Compatibility:

• Direct Bock / GEA Replacements: F16/1751 (Mineral oil / R22 variant, requires oil flush or retrofit conversion), HG16/1751, HGX16/1751, HG4/1751-4, HGX4/1751-4.
• Carrier / Carlyle Equivalents: Direct footprint alternate for Carrier 06EA / 06ER series and Bitzer 4G-30.2 / 4GE-30 variants (minor pipe adaptation required).
• OEM Marine Refrigeration Units: Sabroe / Johnson Controls Marine packages, York Marine Chiller skids, Dometic/Cruisair large marine chillers, Novenco provision cooling plants, Carrier Transicold container and hold units.

Frequently Asked Questions

What is the primary difference between a Bock F16/1751 and an FX16/1751?

The internal mechanical castings and displacement ratings are identical (152.2 m³/h at 50 Hz). The distinction lies in the factory oil charge and elastomeric seal compounds. The F16 designation uses mineral or alkylbenzene oil for HCFC refrigerants (primarily R22), whereas the FX16 is charged with synthetic Polyolester (POE) oil with compatible gasket/O-ring materials designed specifically for HFC refrigerants like R404A, R507, and R134a.

Can I install an FX16/1751 into an existing R22 system?

Yes, but you must drain the factory POE oil charge completely and flush the unit with mineral or alkylbenzene oil (viscosity ISO VG 32 to 46). POE oil in an existing R22 system will break down mineral oil sludge from pipe walls, clogging expansion valves and suction screens.

How is the compressor wired for part-winding start on a 440V 60Hz marine grid?

Connect the supply lines through two separate, interlocked contactors. Contactor 1 feeds terminals U1, V1, W1, and Contactor 2 feeds U2, V2, W2. Set the timer for Contactor 2 to pick up exactly 0.5 to 0.8 seconds after Contactor 1. If starting Direct-on-Line (DOL), bridge U1-U2, V1-V2, and W1-W2 with heavy copper links and connect supply cables to the paired lugs.

What are the correct torque specifications for the cylinder head and valve plate bolts?

During top-end overhaul, clean the head studs and torque the cylinder head bolts in an alternating cross-pattern in three stages: first to 40 Nm, second to 80 Nm, and a final torquing stage to 115 Nm. Run the unit for 2 hours under load, then re-verify torque after the block cools.

What differential oil pressure should be seen on the gauge glass?

The integrated oil pump should generate between 1.4 bar and 3.5 bar above crankcase pressure. An operating differential lower than 0.7 bar indicates a clogged suction filter, high oil dilution from liquid refrigerant washback, or worn pump gear bushings, which will trip the protective safety differential switch.