Ultrasonic Evaluation of Paint Canisters

Abstract

Canisters are used to store liquids such as oil, paint, liquefied glue, and so on. When a customer buys a canister of liquid, they expect the contents to be in pristine condition. The contents of the canister may become defective due to errors in manufacture, transportation, or unfavourable climatic conditions, and the unsuspecting client discovers this after breaking the seal. The vendor will not take the defective goods back after the seal has been broken. One such process that can be used to determine that the products in the canisters are in usable condition is non-destructive testing using ultrasonics. In this method, a transducer is used, which has a transmitter and a receiver. The transmitter is placed on one side of the canister, and the receiver is placed exactly opposite on the other side. Using this, the time taken for the waves to propagate from emitter to receiver (time of flight) is noted and compared with that of standard values. This process allows us to determine whether the contents of the canisters are in good condition or not. The measurements are carried out at three different locations, i.e., the top, middle, and bottom of the canister, and time of flight (TOF) values are recorded. If the content inside the canister is in a liquid state, the TOF is observed at about 54±0.5 microseconds. Due to poor weather conditions, mismanufacturing, or mishandling in transportation, if the canister’s contents have any air pockets, then the contents react and solidify. For this case, the TOF is about 40 ±0.5 microseconds only. A difference of 14 microseconds was observed when the content of the canister changed from liquid sate to solid. This allows us to determine the contents of the canister, without opening the seal.