An on-site liquid storage system normally consists of a tank, a vaporizer, and controls. Systems are selected in accordance with the usage rate, pressure, etc.

Large (bulk) volumes of liquid gases (nitrogen, oxygen, argon, and hydrogen) are delivered by truck and then stored at a customer's facility.

Tanks

The storage vessels generally used for liquefied argon, nitrogen, and oxygen are nominally 500-, 1,500-, 3,000-, 6,000-, 9,000-, and 11,000-gallon tanks. Liquid hydrogen storage vessels are nominally 1,500-, 4,500-, 9,000-, and 20,000-gallon tanks.

Ambient Air Vaporizer

While steam and electric vaporizers are occasionally used, the most widely employed vaporizers obtain heat from the surrounding air. These "ambient air" vaporizers are provided in arrays of many-finned tubes to provide vaporization rates up to 40,000 scfh per array. Additional units are added to provide higher vaporization rates.

Fig. 7 Typical Liquid Storage System Used for Argon, Nitrogen, and Oxygen

Control Manifold

This unit is designed to control the pressure to the customer's houseline and to protect that line from excessively cold gas or possible liquid carryover. The manifold consists of a temperature control valve and a pressure control valve. Also included are the necessary block and bypass valves, as well as a pressure indicator and check valve. There are two basic units—one for rates up to approximately 23,000 scfh and another for rates up to approximately 43,000 scfh.

Fig. 8 Typical Tank Cutaway

Fig. 9 Typical Control Manifold