Semi-hermetic Screw Double-Stage Compressor​

Introduction & Scenario-Specific Solutions

The Need for Double-Stage Compression

Single-stage compressors struggle with ultra-low temperatures (-60°C to -30°C) due to high pressure ratios and motor strain. The Semi-Hermetic Screw Double-Stage Compressor (SLDS series) solves this by splitting compression into two stages—low-pressure (LP) and high-pressure (HP)—reducing energy use by 20% and extending motor life by 50% vs. single-stage ULT compressors.

Scenario 1: Biopharmaceutical Cold Storage

Vaccines, blood products, and gene therapies require stable -40°C to -60°C storage. The SLDS series maintains ±1°C temperature precision, preventing sample degradation (a risk with single-stage compressors, which fluctuate by ±3°C). Its hermetic design also eliminates contamination risks (critical for FDA-compliant facilities).

Scenario 2: Seafood Deep-Freezing

Freshly caught fish must be frozen from 25°C to -40°C within 2 hours to preserve texture and freshness. The SLDS series’ dual-stage compression achieves cooling rates of 0.5°C/min—30% faster than single-stage units—reducing spoilage rates from 8% to 2% for long-haul shipping.

Scenario 3: Industrial Low-Temperature Testing Chambers

Aerospace and electronics industries need chambers for cold shock testing (-60°C to 100°C). The SLDS series’ rapid temperature adjustment (from -60°C to 20°C in 30 minutes) and stable performance make it ideal for testing components like circuit boards or aircraft parts.

Design & Material Innovations

Dual-Stage Compression Structure

• Low-Pressure (LP) Stage: Handles initial cooling from ambient temperature to -30°C using large-diameter screws (67-92mm) for high refrigerant flow.

• High-Pressure (HP) Stage: Further cools to -60°C using smaller-diameter screws (42-67mm) for high pressure.

• Intercooler: Removes heat between stages, reducing motor strain and improving efficiency.

ULT-Resistant Material Selection

• LP Casing: Cryogenic-grade stainless steel (316L) resists brittleness at -60°C—unlike standard steel, which cracks at -40°C.

• HP Screws: Titanium nitride-coated alloy steel, resistant to wear from high-pressure refrigerant flow.

• Motor Windings: Class C insulation (tolerates 220°C), preventing burnout from ULT heat generation.

Intelligent Safety Protection Systems

The SLDS series includes:

• Phase-Loss/Reverse Protection: Shuts down if power phases are reversed or lost (prevents motor damage).

• Winding Temperature Sensors: Triggers shutdown if temperatures exceed 110°C.

• Pressure Relief Valves: Releases excess pressure in the HP stage, avoiding casing damage.

Detailed Technical Specifications

Refrigerant & Operational Specs

• Refrigerant Compatibility: R22 (for -30°C to -40°C), R404A/R507 (for -40°C to -60°C).

• Motor Type: 3-phase, 2-pole semi-hermetic asynchronous motor (high torque for ULT start-up).

• Capacity Adjustment: 100%, 50%, 25% step regulation (adapts to low-load periods).

• Strength Test Pressure: 42 bar (ensures casing safety at high pressure).

Technical Support & After-Sales Services

ULT System Integration Consulting

We collaborate with your engineering team to design custom cold storage or testing chambers, including:

• Refrigerant piping (sized for dual-stage flow).

• Temperature control systems (compatible with PLCs).

• Insulation (e.g., polyurethane foam for -60°C use).

We also provide 3D models of the integrated system for approval.

Cryogenic Maintenance Training

Our 8-hour training sessions cover ULT-specific maintenance:

• Oil replacement in sub-zero conditions (using low-viscosity oil).

• Leak testing with helium (more sensitive for ULT systems).

• Safe handling of cryogenic refrigerants (R404A/R507).

Training is available on-site or via live video for global teams.

Extended Warranty & ULT Spare Parts

• Warranty: 24 months standard; 36 months for biopharmaceutical clients (compliant with FDA requirements).

• Spare Parts: Dedicated ULT parts (e.g., cryogenic seals, LP/HP screws) are stocked in global warehouses—delivered within 2 business days for urgent cases.

Remote Performance Monitoring

Optional IoT-enabled sensors track:

• Evaporation/condensing temperatures.

• LP/HP pressure ratios.

• Motor current and temperature.

Alerts are sent via mobile app if anomalies are detected, allowing proactive maintenance and preventing costly failures.

Productions