In a bulk gas delivery system, knowing the weight of the gas is essential to its transportation. An easy, reliable, and accurate way to measure bulk gases in delivery vehicles is very important, and making the measurement process economical is critical to profitability in the bulk gas supply chain.
Recently, load indicators (LI) have been introduced as a method of weighing bulk gas on cryogenic tank trucks. The load indicatorsensor is a film-type strain gauge and that is brazed on the axle of a cryogenic tank truck. Each truck has its own LI device making weight measurements readily available for that vehicle. In Japan, there are now more than 850 trucks, with loading capacities of about 8–10 tons, that have LIs installed.
Traditional Weighing Technologies
Other ways to measure delivered bulk gas include truck scales, flow meters, and level gauges, but these methods are associated with problems of accuracy and efficiency. With these three options, for example, the results must be manually entered into a computer by the delivery operator and are prone to clerical error. Where distance between the supplier and customer is significant, the use of truck scales makes cryogenic transportation particularly inefficient as most customers do not own scales in Japan. Without a scale at the customer site it is difficult to confirm the exact volume of delivered gas. The absence of scales at customer sites also limits the number of deliveries a truck can make in one run. The loading capacity of a typical cryogenic truck in Japan is up to 10 tons, and delivered amounts can be as little as one ton. A 10-ton truck has the potential to deliver a product to four or five different customers, but without scales at customer sites, accurate measurements cannot be made. The truck has to return to the supply depot after each delivery to recalculate weight. In Japan, such a round trip can be more than 500 km, which takes a full day and uses more than 100 liters of gas.
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