Phase Separators

Installed Phase Separator

PRS-350 Phase Separator

Technifab manufactures phase separators for LN₂ piping systems designed to deliver cryogen that is consistently nearly 100% liquid.

Many types of machines use liquid nitrogen as their medium for heat removal.  In some liquid nitrogen applications, it is necessary that liquid quality be maintained within a tighter tolerance than is possible with a simple keep-full device.  These high quality applications are typically involved in instrumentation but are important to a lesser degree in other applications such as food freezing.  In these applications a phase separator is used.

A phase separator is a vacuum insulated vessel with a liquid cryogen level controller and a pressure safety gas vent system.  Normally the cryogen is vented to the atmosphere through a vent that utilizes a heater to prevent vent plugging.  Cryogenic liquid flows into the phase separator, where its velocity and saturated pressure is reduced to almost zero.  The liquid reaches near zero saturated pressure by evaporative cooling.  In this quiescent state, gas bubbles in the fluid rise to the top of the liquid bath and exit through the atmospheric vent system.  The resulting cryogen is nearly 100% liquid and has an extremely repeatable cooling capacity per pound.  This repeatability is particularly important in electronic testing applications.  If required, a single phase separator can be installed on each user device, or one large phase separator can be utilized to supply high quality liquid to multiple devices.

The dual outlet 15.5 Liter (5 Water Gallon) stainless steel phase separator is the most common configuration sold by Technifab.  It is entirely vacuum jacketed.  The design reduces higher-pressure supply liquid nitrogen to very low pressure, allowing liquid to be received at the user device at only head pressure.  The phase separator is equipped with an adjustable capacitance probe liquid level controller that maintains the liquid level between two pre-set points.  It also provides visual indication of the liquid level as well as a low level alarm.

The function of the phase separator is to simply divide the liquid and gas and then vent the gas from the system.  The separator is normally located close to the point of use.  There are occasions where the phase separator utilizes triaxial piping to deliver the liquid nitrogen to the user device.  The triaxial plumbing allows gas to be vented from the point of entry into the user device, further improving delivered liquid quality.

Technifab has developed for sale three models of the gravity feed phase separator.  The base design is a five-gallon unit with two bayonet outlets.  There is an optional four-outlet unit, and an eight-outlet unit.

Phase Separator specifications

Model (Number of Outlets)	Gross Water Volume (Liters)
2	20.0
4	29.5
8	48.5

Each model utilizes the same electrical controls including adjustable limits capacitance probes to control liquid level.  The inlet control valve is a vacuum insulated unit complete with pneumatic actuation.  The pneumatic actuator is capable of operating on shop air.  An electrical solenoid valve that is activated by the capacitance probes controls the shop air.  A signal conditioner is used to convert the capacitance probe electrical signal to control the 115 VDC solenoid valve.  The unit utilizes Technifab style bayonet connections.  The inlet valve is not integral to the phase separator.  It is remotely mounted using bayonet connections.  The phase separator includes an optional device for vacuum measurement within the annular space.  A vent heater is released as an option.  The phase separator is able to mate to Technifab standard bayonet connections.

For more information or to request a quote, please contact us.