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Pharmaceutical Freeze Drying and Vacuum Drying for Research and Manufacturing in the .01 Torr to 400 Torr Range

Vacuum Pressure is used in Pharmaceutical Manufacturing to: 

  • Help create bulk and active ingredients for FDA approved drug products
  • Increase the shelf-life of a drug product
  • Sterilize medical devices 

Lyophilization, also known as freeze drying, is a process used for preserving biological material by removing the water from the sample, which involves first freezing the sample and then drying it, under a vacuum, at very low temperatures. The low pressure environment helps minimize oxidation during drying.

Lyophilized samples may be stored much longer than untreated samples. The resulting precipitate is a shelf-stable powder. This powdered drug is later reconstituted at point of care for patient use.

Vacuum Drying: Another way vacuum instrumentation is used in the pharmaceutical industry is in vacuum ovens. Vacuum devices are chosen based on the range required for a specific application and are used to measure and/or control vacuum pressure during the process. 

Vacuum ovens applications include: removal of moisture or dehydration, out gassing, bake-out, and to prevent reactions. They are important tools in the medical field for sterilization of medical devices, as well as glassware for research purposes.

Vacuum drying helps to maintain the integrity of the original item without damaging it with heat since drying can be accomplished at a lower temperature while under pressure. This is valuable for food and pharmaceutical processing since other drying processes can degrade the quality and/or make heat-sensitive drug products (Parikh, D, 2015). 

Although all drying techniques share a common objective (i.e., dehydration), conceptually they are different and require modification/adaptation based on the properties of the compound being processed. 

For high value products, like pharmaceuticals, the cost of the raw ingredient may be the primary driver for the selection of the processing method. The majority of pharmaceutical compounds are susceptible to stresses that develop during freezing and drying.

Formulations undergoing freeze‐drying can be sensitive to deviations in temperature and chamber pressure, which may be exacerbated in a freeze dryer with poor temperature and chamber pressure control, thereby leading to additional losses in process efficiency as well as poor product appearance and quality attributes.

2 Drying Methods that Use Vacuum

1. Vacuum Ovens

A vacuum drying oven is most often used for delicate drying processes, such as drying tiny parts or removing flammable solvents.  

    • The low-pressure environment also minimizes oxidation during drying. 
    • A standard vacuum oven can operate at temperatures as high as 200°C to 250°C. 
    • Vacuum pressure is normally between 10 Torr to 100 Torr range.
    • Applications: Vacuum drying has proven effectiveness in manufacturing probiotics, food and enzymes 

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Sources: Santivarangkna 2007, Foerst 2012, Bennett 2007, Palacio, 2012, Long 2007, Rossi 1997, Uritani 1995

2. Freeze-drying (or lyophilization)

Freeze drying is a water removal process typically used to preserve perishable materials, to extend shelf life or make the material more convenient for transport.

Freeze drying works by freezing the material, then reducing the pressure and adding heat to allow the frozen water in the material to sublimate. Sublimation means going  from its solid frozen state to its gaseous state without ever passing through its liquid phase. 10-Figure2-1_Semantic Scholar_Phase Diagram of Water

Vacuum pressure is normally below 5 Torr.

  • The freeze-drying process has important applications in the pharmaceutical and biotechnology industries.
  • This process requires the use of vacuum for the drying of heat-sensitive drugs and biologics at a lower temperature.
  • Freeze-drying is mainly used to improve the stability and storage of easily altered drugs.
  • Commonly applied to the production of injectable dosage forms of drugs, pharmaceutical freezedrying is also used to produce diagnostics

Why partner with DigiVac?

DigiVac has been designing and manufacturing scientific measurement, control instruments and freeze dryer controllers since 1983.  We can also work with you on custom solutions with our team of software and hardware engineers. Our customers appreciate our attention to detail, predictable lead times and the ability to respond quickly to customer urgency.

DigiVac Product Highlights for Freeze Drying and Vacuum Ovens | .01 Torr to 400 Torr

Concerto | Vacuum & Pressure Controller

Control Up to 4 Vacuum Ovens or Chambers at Once with 1 Vacuum Pump


  • Simplify Your Lab & Control More With Less
  • Maximize Throughput With a 17.5 mm vacuum path to each hose barb
  • Precision Control & Intuitive Design
    • Control Range: 2 Torr to 760 Torr
    • Unique Vacuum Control: proportional throttle and proportional bleed control (vent to ATM) delivered from an integral dual valve module per channel

StrataVac Throttle Vacuum Control 775i Bundle

The STRATAVAC  bundle with plunger-type vacuum control comes with a rugged industrial valve with a smaller .5″ orifice giving you a faster acting valve with tighter control on your process.


  • Ideal for measuring and controlling vacuum ovens for vacuum drying applications
  • Measurement Range: 1 Torr – 775 Torr range (medium vacuum range) for pharmaceutical and industrial applications
  • Control Range: of 2 Torr to 770 Torr
  • Extends life of pump by enabling pump to run closer to its base pressure

StrataVac Controller | Bleed Vacuum Control Bundle

The StrataVac bundle with bleed vacuum control helps increase molecular flow and throughput.


  • Ideal for controlling vacuum level in freeze dryers
  • Rich remote command line interface for integration with PLCs
  • Bleed in inert gases like air, nitrogen, or argon to assist in vacuum drying
  • Accuracy Range: .001 Torr to 6 Torr
  • Control Range: 1 Micron to 6000 Microns (.001 Torr to 6 Torr)

Bullseye Precision Gauge with 536 KF25 Sensor

Portable Vacuum Gauge with rugged sensor


  • More accurate then most OEM vacuum gauges that are integrated in the freeze-dryer, and when ordered with a NIST certification can be used as a cGMP reference
  • Patented vacuum gauge includes an Agilent 536 sensor that has an integrated baffle that provides protection and helps reduce sensor failure.
  • Has 12 measurement units for implementation in almost any vacuum application (Torr, mbar, bar, kPa, inches of Hg, mm Hg, millitorr, microns, inches of water, PSI, Pa)
  • Measurement range:  .001 Torr to 800 Torr

The Model 450 

The Model 450 Vacuum Controller measures 1-760 Torr and includes a proportional valve for vacuum regulation.

m450-300x300 (1)

Premium stainless-steel vacuum path model to support use in corrosive or volatile applications.

  • Super simple to use: just dial in your vacuum set point
  • Maximized pump down speed: designed with a much larger bore (9/32”) proportional valve (compared to alternatives) that allows the controller to make precise changes in vacuum flow to achieve a very stable vacuum level
  • Ability to purge system to atmosphere with a simple front panel switch

The Model 276

The Model 276 bench top vacuum gauge has two relay set points and has a wide vacuum range to provide accurate and reliable pressure readings. 

Model 276 | Dual Sensor Vacuum Gauge

  • It can display readings in Torr with optional mbar and can be purchased with set point relays, ethernet, and RS232 features
  • Measurement Range:  1 millitorr to 760 Torr

Support for Process Documentation to Comply with cGMP for Pharmaceutical Applications: The Model 276 can be synced with online vacuum analytics software, placed near the vacuum oven, and set up with an RS232 backup so pressure readings are not lost.

DIGIVAC has been a vital component in freeze dryers and vacuum drying applications for over 30 years.