−135°C Mechanical Cryogenic Freezer

What is the −135°C Mechanical Cryogenic Freezer?

A −135°C mechanical cryogenic freezer is a single-refrigerant-loop or mixed-refrigerant unit reaching about −135°C to −140°C, at the edge of the glass transition region. It is the right choice for laboratories that need deep storage below −86°C without the cost and complexity of a −150°C cascade system.

Overview

Units at this temperature sit between standard ultra-low freezers and −150°C cryogenic freezers. They use a two-stage cascade or mixed-refrigerant system that is less demanding than deeper systems, giving lower energy use and a lower purchase cost. Typical capacity is 200 to 500 L in upright or chest format. Chest designs retain cold better during opening because cold air stays in the tub, and upright models give easier box access. The setpoint is usually adjustable from −100°C to −135°C, which is useful for material that needs to be stored below −130°C but not at vapor-phase nitrogen temperature. Temperature uniformity is about ±5°C, and pull-down time is 4 to 8 hours. Backup injection, alarms and USB data logging are available. The unit suits laboratories that keep valuable reagents and biological samples where −80°C is marginal.

How does it work?

Mechanical cryogenic freezers reach −150°C through multi-stage refrigeration. A cascade system links two or three compressor circuits, each with a different refrigerant, so that the evaporator of one stage cools the condenser of the next. Mixed-refrigerant systems use a single compressor with a blend of refrigerants that evaporates across a wide temperature range. Vacuum insulation panels and thick foam limit heat gain, and the chamber uses uniform air circulation or conduction shelves. Controlled-rate freezers follow a different principle, injecting liquid nitrogen or using a cold head to cool the chamber along a programmed ramp, commonly −1°C per minute, with a controller and sensors that follow temperature setpoints. Both types use PT100 sensors, alarms, and backup options such as liquid nitrogen injection or carbon dioxide.

What are the key features?

• Setpoint adjustable from −100°C to −135°C for flexible storage needs.
• Two-stage cascade or mixed-refrigerant system with lower energy use than −150°C units.
• Upright and chest formats available for different access patterns.
• Microprocessor controller with USB logging and relay alarm contacts.
• Vacuum insulation panels and gasketed inner doors limit heat gain.
• Optional liquid nitrogen or CO2 backup for power failures.

What are the technical specifications?

A typical −135°c mechanical cryogenic freezer configuration offers temperature range of −100°C to −135°C, capacity of 200–500 L, temperature uniformity of ±5°C, pull-down time of 4–8 h from ambient, refrigeration system of Two-stage cascade or mixed refrigerant and energy consumption of 8–15 kWh/day. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The −135°C Mechanical Cryogenic Freezer is used in deep storage of valuable reagents, research cell line storage, backup to −150°C storage and long-term tissue storage. Across the wider Cryogenic Freezers class, laboratories also deploy it for biobank sample storage without liquid nitrogen, cell line and primary cell storage and controlled-rate freezing of cell therapy products.

Which standards and certifications apply?

Relevant standards and methods include IEC 61010-1, IEC 61010-2-011, ISO 20387, ISO 21009-1, EN 61326-1 and GB 4793.1. Certification candidates for this model are CE, ISO 9001 manufacturing and IEC 61010-1; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Mechanical cryogenic freezers release substantial heat, often 1–3 kW, so allow at least 20–30 cm of clearance and adequate room cooling. Use a dedicated circuit with a stable supply and consider a UPS or a backup generator, as well as a liquid nitrogen or carbon dioxide backup injection system. Keep the ambient temperature below about 32°C. Limit door opening time and avoid loading warm samples in bulk. Clean the condenser filter every one to three months. Calibrate temperature sensors at least annually, test the alarms and log temperature continuously. Controlled-rate freezers need a clean liquid nitrogen supply, exhaust ventilation and oxygen monitoring. Plan service access and preventive maintenance contracts.

How do I select the right −135°C Mechanical Cryogenic Freezer?

Select a −135°C unit when −80°C is insufficient but the cost and energy of −150°C storage are not justified. If your protocol names −150°C or colder, choose a full cryogenic unit. In an RFQ, specify format, capacity, achieved temperature at full load, logging and backup injection.

How does it compare with other Cryogenic Freezers variants?

Decide first between storage and freezing. For storage, compare mechanical freezers at −135°C to −150°C and liquid nitrogen vessels, weighing the benefit of no nitrogen supply against dependence on electricity. Check that the stated temperature is achieved at full load and at your room temperature, not only when empty. Size capacity in boxes or vials and examine the shelf or rack format. Compare power consumption, heat rejection to the room, noise, recovery time after door opening and alarm and backup options. For controlled freezing, confirm rate range, number of programmable steps, sample holding format and whether liquid nitrogen supply is acceptable. For regulated work, add data logging, password control and calibration support.