SEMIFLEX® is a bendable and flexible piping system
for liquid nitrogen consisting of two concentric, corrugated
tubes separated by a Teflon spacer. The space between
the tubes – the vacuum jacket - is sealed under
Sealed SEMIFLEX® is available
in two different sizes. . The outside is protected
with black polyethylen coating.
Sealed SEMIFLEX® provides fast cool-down, constant liquid quality and trouble free operation. With the temperature of the outer tube being only some degrees below ambient temperature the system is free of moisture and ice.
Sealed SEMIFLEX® is produced in sections of limited lengths for outdoor and indoor use. The sections are connected by bayonets and are easy to install. Tees, crosses, bayonets, end traps, vents and phase separators allow any system configuration and guarantee that Sealed SEMIFLEX® is easily adjustable to any modification.
Sealed SEMIFLEX® can be combined with COBRAFLEX® flexible hose to provide efficient connections to use points.
Advantages ofSEALED SEMIFLEX®
With Sealed SEMIFLEX® you enjoy significant reductions in LN2 consumption on a continuous basis since Sealed SEMIFLEX® Systems have a very low cool down and steady state heat loss.
Every pipe is helium leak tested and cold shocked to insure its vacuum integrity.To achieve a long service life every hose is heat soaked during evacuation and is equipped with chemical getters.Each hose is sealed under high vacuum with a combination seal-off / annulus relief valve.
Sealed SEMIFLEX® systems are designed for quick low-cost installation that does not interfere with production. Factory fabricated and tested, the pipe is simply hung and connected to equipment. The bendable nature of Sealed SEMIFLEX® pipe greatly simplifies installation. There are no critical field joints. Bayonet connections avoid costly welding of sections.
Sealed SEMIFLEX® pipe requires no maintenance.
Worldwide service support
With offices throughout the world and a service network in Europe VBS Europe and VBC provide support at each of your facilities on a timely and personal basis.
Points to consider inLN2 Pipe System Design
In any vacuum insulated pipe system, the LN2 losses attributable to heat leak in the pipe are miniscule compared to the losses which occur in the system as a whole. The major portion of heat loss occurs from the following factors:
In a typical pipe system connected to a bulk storage tank, the interface between the tank and the vacuum insulated pipe is bare copper pipe with a main shut off valve and safety relief valve assembly. This connection will normally have a loss rate of 2 to 7 kg of LN2 per hour or more. Losses here flow through the entire pipe system as gas (GN2) along with the liquid. Sealed SEMIFLEX® systems can effectively eliminate tank connection losses by using a vacuum insulated tank bayonet and valve.
This part of the system, between the end of the vacuum insulated pipe and the actual use point, is typically copper tube with a shut off valve, safety relief valve assembly, and a solenoid valve connected to a sensor control. Losses average 1 to 4 kg of LN2 per hour. To minimize these losses, controls should be configured so that connections are active only to satisfy equipment requirements, and not constantly. Sealed SEMIFLEX® systems minimize equipment connection losses.
"Flash" is caused by the reduction of pressure when a valve is opened to withdraw liquid or when liquid is passed through a pressure reducing valve of any kind. At 7 bar, flash losses approach 30% of liquid used. Since Sealed SEMIFLEX® systems substantially reduce overall consumption of LN2, flash losses are also minimized.
Two phase flow
Even a small heat leak in an LN2 delivery system generates a large volume of gas. At – 196°C, LN2 converts to GN2 at a ratio of 177 to 1; as LN2 warms to ambient temperatures, the ratio approaches 700 to 1. Since all LN2 pipe systems will have some flash loss and pipe heat leak, two phase flow (liquid/gas) will occur in the pipe.
For many applications, however, a supply of LN2 in pure liquid form is preferable. Only SEMIFLEX®/Triax Systems are capable of completely eliminating two phase flow of LN2 to use points.
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