Nitrogen Inflation for Passenger Car and Light Truck Tires

Abstract Nitrogen as an inflation gas for passenger car and light truck tires use is widely available commercially. Consumers are confronted with a bewildering selection of offerings, and suppliers tout the purity of their nitrogen generation systems and effectiveness of using the gas in place of air. This paper develops models for the initial tire nitrogen purity, the inflation pressure loss rate, and the evolution of the nitrogen gas purity in the tire as a function of the gas used to top off the tire over its life. A series of simulations using the basic model is developed for air and various purities of nitrogen initial inflation with monthly top-off using air or various purities of nitrogen. The initial inflation pressure loss rate is shown as a function of the tire’s initial nitrogen purity. This paper proposes the use of the total oxygen passing through the tire over its lifetime as a metric for evaluation of various inflation schemes. This metric is developed for several of the popular available nitrogen inflation purities using both air and nitrogen as a top-off gas.

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Effect of Measurement Frequency and Test Duration on the Inflation Pressure Loss Rate of Radial Medium Truck Tires

Tire Science and Technology ◽

10.2346/tire.15.430404 ◽

2015 ◽

Vol 43 (4) ◽

pp. 325-337 ◽

Cited By ~ 1

Author(s):

Jonathan E. Martens ◽

Edward R. Terrill ◽

R. Christopher Napier ◽

Walter H. Waddell

Keyword(s):

Pressure Loss ◽

Loss Rate ◽

Pressure Gauge ◽

Test Method ◽

Test Duration ◽

Testing Time ◽

Inflation Pressure ◽

Measurement Frequency ◽

Truck Tires ◽

Data Points

ABSTRACT The inflation pressure loss rate (IPLR) of a tire has been a standard test method for several decades and is used to determine the rate at which a tire will lose pressure. Following these procedures, the rate of pressure loss is obtained and expressed numerically as the percentage of loss per month. This is an investigation of two experimental variables: (1) the frequency at which the inflation pressure is measured on a daily basis, and (2) the duration of the entire test. The measurement frequency means how many data points are recorded during a 24-hour period. For example, one study may collect data as infrequently as once per day by manually reading a pressure gauge every 24 hours. Alternatively, another study may collect data electronically with pressure transducers capable of transmitting large numbers of data points over short preset periods, then numerically averaging those data into a single 24-hour daily measurement. After a 21-day period to equilibrate the newly inflated tire, the test duration can range from 90 to 180 days but is allowed to be shortened when using electronic-pressure monitoring. This is a study of data-collection frequency and duration in a newly commissioned tire IPLR laboratory at Akron Rubber Development Laboratory, Inc (ARDL). It was constructed to have excellent temperature control and was equipped with 24 pressure-sensitive transducers with data being directly transmitted into a dedicated computer where the ASTM F1112 equations were applied. The present study includes data measurements from 56 radial medium truck tires manufactured by different companies. Results were obtained by averaging data collected four times per hour over a test duration of 90 days but were then recalculated using 60, 45, or 30 days of data to establish the feasibility of using a shorter testing time.

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