AN article or product regarded as a scientific curiosity by one generation not infrequently becomes a commonplace of the next. The vacuum flask used by Dewar to preserve very cold liquids at normal pressure has become a household necessity for retaining the temperature of warm liquids, and, under modern mass-production methods, the glass flask is now obtainable at a remarkably low price. The metal vacuum vessel, with charcoal in connexion with the vacuous envelope, is less widely known. It is not suitable for the retention of hot liquids; but by reason of its relative robustness and of the large sizes in which it can be made, it is preferable to the glass form for the storage and transport of liquid oxygen or liquid air. Without question, the introduction of the metal vessel has rendered possible such expansion in the commercial and scientific uses of liquid oxygen as is now slowly proceeding. That the importance of the metal vacuum bottle is fully realised, becomes clear upon a perusal of the recently published Report of the Oxygen Research Committee.1 Quite 90 per cent, of the Report is devoted to the manner of construction of these vessels, to the mode of testing them, to the evacuation of the envelopes, and to certain ancillary but vital problems, particularly those concerned with the behaviour of gas-adsorbents (activated charcoals, colloidal silica, etc.) at liquid-air temperature. Though the general reader may regret the absence from the Report of information” respecting both the manufacture of oxygen and the specific uses to which the liquid is put, the Committee has decided wisely in limiting its survey to the aspect of its subject which its members have experimentally studied.
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“How do I operate a liquid dewar pressure builder?” is one of the most frequently asked questions from gas customers. In this article, we provide a better understanding of what a pressure builder is, how it works, and how to safely and properly use it.
What is the purpose of the pressure builder?
Without a pressure builder, a tank’s pressure might take several hours or days to build up to the level needed for a specific application. Using the pressure builder means the tank’s pressure will reach the desired level much more quickly, typically in 10 to 20 minutes. Some of the applications for which you might use the pressure builder include supplying nitrogen to a mass spectrometer or high-pressure manifold.
How does the pressure builder work?
When the pressure builder valve is opened, it allows liquid nitrogen to be introduced into the tank’s evaporation coil, which wraps around the inner and outer wall of the tank. This creates heat and builds pressure in the tank.
How do I locate the pressure builder valve?
There are several different valves on top of a liquid dewar, each with a tag that identifies what that specific valve is used for. Depending on the manufacturer, the pressure builder valve might look slightly different. It’s critical to read the tags to make sure you identify the correct valve that you are adjusting. If you’re looking for the pressure builder valve, search for the tag labeled “PB.”
How do I set the tank pressure?
Some pressure builders are designed so that the end user can adjust the pressure themselves. There are several steps that you should follow to ensure you do this properly and safely.
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If I hear a loud hissing or popping noise coming from the safeties, is there an issue?
This noise is normal and occurs when the tank’s pressure has built up to the maximum pressure setting. If this noise is bothersome, you may want to consider getting a whisper valve. This device can reduce the hissing noise as well as limit the amount of product lost from the safeties on the tank.
What do I do if I find any leaks?
Do not under any circumstances attempt to block or remove any of the safety devices on the tank to stop the leak. Immediately set the cylinder aside, mark the defective item with tape or a note, and call customer service at your gas distributor.
Have additional questions or need more help with your liquid dewar pressure builder? The Middlesex team is happy to be of service, so feel free to contact us.
Middlesex Gases is a preferred partner through MassBioEdge.
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About Middlesex Gases
Middlesex Gases is a family-owned, third-generation supplier of specialty, medical, and industrial gases and a variety of gas systems, including Bulk, MicroBulk, and Cryopreservation. The company was founded in by welder Joseph Martin Sr. as Middlesex Welding Supply, in Everett, Massachusetts. Today, Middlesex still offers expertise in industrial and welding gases and products but has evolved to focus more resources on serving the ever-increasing gas requirements of businesses in life sciences, biotech, and health care. Middlesex is now the preferred vendor for the Massachusetts Biotechnology Council (MassBio), the Massachusetts Medical Device Industry Council (MassMEDIC), and BioCT, Connecticut’s biotechnology community. With three fill plants, five supply stores, a state-of-the-art specialty gas lab and new medical CO2 lab, and a large fleet of trucks and trailers, Middlesex Gases delivers superior gas products and solutions wherever and whenever its customers need them.
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