Making it profitable for modern industry to automate liquid nitrogen use with innovative solutions when handling cryogen.
Vacuum Barrier`s line of cryogenic hose and pipe eliminate frost, moisture and ice ball problems and provides low cool down and steady state heat loss for superior thermal performance. Vacuum Barrier offers 47 years of experience in the design, fabrication and manufacturing of cryogenic pipe and hose.
Vacuum Barrier continues to provide innovative solutions to the problems associated with handling cryogen and make it profitable for modern industry to automate liquid nitrogen use.
Points to consider in liquid nitrogen pipe system design
HEAT LOSSES
Any vacuum insulation pipe system, the liquid nitrogen losses attributable to the 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;
Tank Connection: 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 assembly. This connection will normally have a loss rate of 5 to 15 pounds of liquid nitrogen per hour or more. Losses here flow through the entire pipe systems as gas along with the liquid. SEMIFLEX® systems can effectively eliminate tank connection losses using a vacuum insulated tank bayonet and valve.
Equipment Connection: This is the part of the system at the end of the vacuum insulated line. It consists of a non-jacketed valve and safety relief valve. Losses average 3 to 10 pounds of liquid nitrogen per hour. To minimize these losses, controls should be configured so that connections are active only to satisfy equipment requirements and not constant. SEMIFLEX® systems minimize equipment connection losses.
Flash Loss: “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 100 psig, flash losses approach 30% of liquid used. Since SEMIFLEX® systems substantially reduce overall consumption of liquid nitrogen, flash losses are also minimized.
TWO PHASE FLOW
Even a small heat leak in a liquid nitrogen delivery system generates a large volume of gas. At -320F, liquid nitrogen converts gas at a ratio of 300 to 1; as liquid nitrogen warms to ambient temperatures, the ratio approaches 700 to 1. Since all liquid nitrogen 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 liquid nitrogen in pure liquid form is preferable. Only SEMIFLEX®/Triax systems are capable of completely eliminating two phase flow of liquid nitrogen to use points.
Products Include: Dynamic SEMIFLEX®, Sealed SEMIFLEX® SEMIFLEX® Triax and COBRAFLEX®
