BOCK Semi-Hermetic Compressor Catalog, HGX and HGZX Models

BOCK Semi-Hermetic Compressor: What It Is and Why It Is Preferred

BOCK semi-hermetic compressors are reciprocating compressors that form the backbone of industrial refrigeration systems and provide long service life thanks to their serviceable housing design. Unlike fully hermetic (brazed, sealed) and scroll compressors, in the semi-hermetic design parts such as the cylinder head, bearings, piston rings and valve plate can be accessed in the field; this significantly reduces operating costs in cold room, supermarket section refrigeration and process cooling applications.

For HVAC technicians and refrigeration engineers, Yedepa.com keeps an up-to-date technical database and price information for original HGX and HGZX series compressors from GEA Bock GmbH. The rest of the page explains for B2B users the technical differences between the 56e, 66e and 88e platforms, refrigerant compatibility and selection criteria.

About GEA Bock GmbH: German Engineering Since 1932

Bock GmbH was founded in 1932 in Frickenhausen, Germany and, with almost a century of history, has become one of the world-renowned brands in semi-hermetic reciprocating compressor manufacturing. Even after separating from the GEA Group in 2014, the company continues production under the Bock trademark and offers a wide product range for commercial refrigeration, transport refrigeration, heat pump and CO2 (R744) applications.

In the Turkish market, Bock compressors are especially preferred in industrial cold storage, milk cooling tank, fish-meat processing plant and supermarket section refrigeration systems. Yedepa.com is one of the addresses technicians turn to for the supply of spare parts, oil and accessories for these compressors.

HGX Series vs HGZX Series: The Single-Stage and Two-Stage Difference

Bock's two most frequently confused product families are the HGX (single-stage) and HGZX (two-stage) series. Choosing the correct series is critical for system efficiency and compressor life.

HGX Series - Single-Stage Reciprocating

The HGX series is aimed at medium and high evaporating temperature (MBP/HBP) applications. It works compatibly with refrigerants such as R404A, R134a, R407C and R513A. Typical areas of use:

Supermarket section refrigeration (MBP, -10 °C / -15 °C)
Air conditioning and process cooling (HBP)
Cold room (medium temperature, +2 °C / +5 °C)
Beverage cooling and milk tank applications

HGZX Series - Two-Stage LBP

The HGZX series, on the other hand, is designed for low evaporating temperature (LBP) applications. Thanks to two-stage compression, it operates much more efficiently than single-stage models at evaporating temperatures of -40 °C and below. Frozen food storage, blast freezing tunnels, fish freezing and industrial low-temperature processes are typical areas of use. The BOCK HGZX7/2110-4, BOCK HGZX7/1860-4 and BOCK HGZX7/1620-4 models in the Yedepa.com catalog are reference models operating in two stages with R404A/R507 refrigerants. The HGZX7/1860-4 also reaches the field with a liquid subcooler option.

56e, 66e and 88e Platform Differences

Bock's e-series (efficient) platform offers three main housing sizes according to capacity. The table below summarizes the platform, number of cylinders, protection class and refrigerant compatibility of the models in the Yedepa.com catalog.

Model	Platform	Cylinders	Protection	Refrigerant	Type
HGX88e/3235-4 S	88e	8	IP65	R404A / R134a	Single-stage
HGX88e/2735-4 S	88e	8	IP65	R404A / R134a	Single-stage
HGX88e/2400-4 S	88e	8	IP65	R404A / R134a	Single-stage
HGZX7/2110-4	HGZX7	6	IP65	R404A / R507	Two-stage (LBP)
HGZX7/1860-4	HGZX7	6	IP65	R404A / R507	Two-stage + subcooler
HGZX7/1620-4	HGZX7	6	IP65	R404A / R507	Two-stage (LBP)
HGX66e/2070-4 S	66e	6	IP66	R404A / R134a / R513A	Single-stage
HGX66e/1750-4 S	66e	6	IP66	R404A / R134a	Single-stage
HGX66e/1540-4 S	66e	6	IP66	R404A / R513A	Single-stage
HGX66e/1340-4 S	66e	6	IP66	R404A / R134a	Single-stage
HGX56e/1155-4 S	56e	6	IP65	R404A / R134a	Suction gas cooled
HGX56e/995-4 S	56e	6	IP65	R407C / R134a / R404A	Single-stage

56e Platform

With a more compact size, 6-cylinder design and mid-segment capacity, these are the workhorse compressors of the field. The HGX56e/995-4 S and HGX56e/1155-4 S are frequently preferred in retrofit projects requiring backward compatibility with traditional refrigerants such as R407C and R134a.

66e Platform

It is the most common platform for supermarket central refrigeration racks, medium-to-large cold stores and air conditioning applications. The HGX66e/2070-4 S model in the Yedepa.com catalog, with 440-480 V Y/YY connection and 60 Hz supply, is especially preferred in Middle East and North Africa projects. Thanks to its IP66 protection class, the 66e family is resistant to dust and water spray in outdoor condensing units.

88e Platform

It is the compressor for heavy-duty industrial applications. With their 8-cylinder design, the HGX88e/3235-4 S, HGX88e/2735-4 S and HGX88e/2400-4 S models operate in large cold stores, meat processing plants and industrial process cooling systems. With a 380-420 V supply range, they are directly compatible with the Turkish grid.

What Do the IP65 and IP66 Protection Classes Mean?

The resistance of the compressor's motor terminal box and housing to dust/water ingress is expressed with the IP (Ingress Protection) code. The IP65 and IP66 classes are used in the Bock 56e, 66e, 88e and HGZX7 series:

IP65 - Full protection against dust + protection against low-pressure water spray from all directions. Sufficient for indoor and standard outdoor condenser applications.
IP66 - Full protection against dust + protection against powerful water jets from all directions. Especially preferred for coastal regions, rainy climates and facilities with washdown floors (such as food factories).

Refrigerant Compatibility (R404A, R507, R134a, R407C, R513A)

Due to F-Gas regulations and GWP (Global Warming Potential) targets, high-GWP refrigerants such as R404A are being phased down in Europe. Bock's modern e-series compressors come with a wide refrigerant list to support this transition:

R404A - Still common in low and medium temperature commercial refrigeration; however, the shift to alternatives is increasing in new facilities.
R507 - An azeotropic blend frequently used together with R404A in HGZX7 series two-stage compressors.
R134a - The standard refrigerant in medium/high temperature applications, heat pumps and beverage coolers.
R407C - The transition refrigerant after R22 in air conditioning applications; models such as the HGX56e/995-4 S can operate with this refrigerant.
R513A - The low-GWP alternative to R134a (approximately 631 GWP); can be used in the HGX66e/2070-4 S and HGX66e/1540-4 S models.

When changing refrigerant in the field (retrofit), oil compatibility, expansion valve selection and readjustment of suction/discharge pressure protection devices are mandatory. The Yedepa.com technical team stocks original Bock POE and mineral oil options for facilities planning a refrigerant transition.

What Does the S Suffix Mean? Lubrication and Cooling Detail

The letter Sat the end of Bock model names indicates, in Bock terminology, the version that includes improved lubrication or suction gas cooling in addition to the standard configuration. For example, the HGX56e/1155-4 S model comes with a suction gas cooled design; this provides better cooling of the motor windings at high discharge temperatures. On the field side, the 'S' suffix version means a wider operating envelope and fewer thermal trips.

Industrial Application Areas

The field application of Bock semi-hermetic compressors needs to be set up correctly. A typical project list from technicians consulting Yedepa.com:

Supermarket central rack - 66e platform, 3-6 compressors in parallel, R404A or R513A
Cold room (medium temperature) - HGX88e family alone or in parallel
Blast freezing tunnel and freezing - HGZX7 series two-stage, R404A/R507
Meat and dairy processing plant - 66e models with IP66 protection class, washdown floor compatible
Industrial process cooling (chiller) - 56e and 66e platform with R134a/R513A
Potato / vegetable storage - Large-volume cooling with the 88e platform

Selection Criteria for HVAC Technicians and Refrigeration Engineers

Compressor selection should not be made by looking only at the cooling capacity (kW). The criteria to be considered according to the field experience of the Yedepa.com technical team:

Evaporating and condensing temperature envelope - The model's envelope chart must cover the project conditions.
Refrigerant and oil compatibility - If a refrigerant change is planned, the compressor approval list should be checked.
Grid voltage and frequency - 380-420 V/50 Hz is the Turkish standard; in 60 Hz projects, models such as the HGX66e/2070-4 S come to the fore.
Protection class - IP66 is recommended for outdoor and washdown floor use.
Service access - Thanks to the semi-hermetic design, valve, piston ring and bearing replacements can be made in the field; this is a major TCO advantage.
Spare parts supply - The supply time of the valve plate, piston ring set, main bearing, oil pump and electrical protection module should be checked.

The Yedepa.com Advantage: B2B Technician- and Service-Focused Supply

In addition to Bock compressors, Yedepa.com offers complementary products needed by the refrigeration sector, such as Danfoss controls, Alco filter driers, Castel solenoid valves and copper pipe, under one roof. Special support is provided to B2B suppliers for pre-order technical approval, serial number verification and the invoicing process. You can reach us via Yedepa.com with your facility's inventory list and request a project-specific quote.

Bock Compressor Maintenance and Service Notes

The key to getting a long life from a semi-hermetic compressor is adherence to the maintenance schedule prescribed by the manufacturer. According to field experience, the most common causes of failure in Bock HGX and HGZX series compressors are incorrect monitoring of the oil level, clogging of the suction filter, incorrect parameterization of the discharge temperature protection device (e.g. INT69) and incorrect superheat setting of the expansion valve. With the original Bock oil pump, oil pressure switch and INT69 module available from Yedepa.com, you can complete the replacement in the field in minimum time.

Periodic Maintenance Recommendations

In parallel with Bock's technical documents, the following interval recommendations stand out in field practice:

Every 2,500 - 5,000 hours: Oil analysis, oil change and filter check.
Every 10,000 hours: Check of the valve plate and suction/discharge valve reeds; renewal if necessary.
Every 20,000 - 40,000 hours: Check of the piston ring set, piston and cylinder liner; main bearing evaluation.
Annually: Electrical protection module (INT69) and motor winding insulation measurement.

Being able to carry out these maintenance items in the field is a direct benefit of the semi-hermetic design; in a fully hermetic compressor, the same failure would mean replacing the entire unit. The spare parts range offered by Yedepa.com is the practical counterpart of this TCO advantage.

Ordering and Technical Support Process

Before sourcing a Bock compressor, having information ready such as the existing system's refrigerant, evaporating/condensing temperature, cooling capacity (kW), electrical panel configuration (star-delta, soft starter, VFD) and suction/discharge pipe diameters speeds up the quotation process. When you create a model-based request via Yedepa.com, the technical team verifies the project conditions on the envelope chart and offers an alternative model suggestion if necessary.

Frequently Asked Questions (FAQ)

1. Can BOCK compressors be serviced in Turkey?

Yes. Thanks to the semi-hermetic design, parts such as the cylinder head, valve plate, piston ring set, main bearing and oil pump can be replaced on site. Original Bock spare parts can be supplied via Yedepa.com; an authorized service network is also available nationwide.

2. What is the main difference between HGX and HGZX?

HGX is a single-stage reciprocating compressor designed for medium/high evaporating temperature applications. HGZX has a two-stage design and offers much higher efficiency in low evaporating temperature (LBP, -35 °C and below) applications. The HGZX7 series is preferred for frozen food and blast freezing tunnels.

3. What is the advantage of the 88e platform over the 66e?

Thanks to its 8-cylinder design, the 88e platform reaches a much higher cooling capacity with a single compressor. In large cold stores, meat processing plants and industrial process cooling, it reduces the number of compressors, lowering the complexity of the electrical panel, piping and oil circuit.

4. Will R404A no longer be used? Which alternative should I switch to?

R404A is being phased down in Europe due to its high GWP value. R513A or R134a can be considered for medium temperature applications, and blends such as R448A/R449A for low temperature. The transition decision should be made according to the age of the existing system, the compressor approval list and the investment budget. The Yedepa.com technical team can provide project-specific guidance.

5. Is IP65 sufficient outdoors?

Under standard climate conditions, IP65 is sufficient in outdoor condensing units. However, for coastal regions (salt corrosion), food facilities with high-pressure washing and regions with heavy rainfall, the IP66 class (e.g. the 66e family) is recommended.

6. How can I be sure that the Bock compressor I ordered is original?

Manufacturer verification can be done via the serial number on the housing of each Bock compressor. Compressors supplied via Yedepa.com are delivered with an invoice, origin information and serial number; manufacturer verification support is provided when necessary.