What are Negative Leak Rates? - Pressure Decay Leak Testing

What are negative leak rates? How do they occur? Find out the answers to these questions and more as Russ walks us through an understanding of negative leak rates.

[@juliantrotter527]

Looking good Russ 👍. Great video.

[@lwisromero1392]

Your explanation was perfect! Thank you so much for this information.

[@mike5er89]

Ever have customers setup their system to flag their “worst” negative “leakers” to be their new leak standard? To an extent of course. Something I’ve been wanting to do lately.

[@capexsalesllc7281]

Sup Mike! Sorry for the delay. Setting your worst negative leakers aside can definitely be a strategy for ensuring that you are utilizing the ideal part as the master. The "Ideal" master part is a part that represents the parts that will be tested on the equipment but is leak free. I encourage customers that are calibrating their equipment for the first time to select any part to calibrate the equipment with and then test at least 30 other parts (documenting the leak rate of each part). After processing all 30 parts they should select the most negative part as the master part and recalibrate the equipment with that part. Hope that is helpful. Thanks for the question!

[@captainkc6014]

Hello, I did the trial using differential pressure decay method as follows: condition 1. increase temperature of work part(heated up by hot gun) -result shows in negative condition 2. decrease temperature of work part(kept in freeze )-result in shows in negative Is it ok?- reading shown after increasing work temperature but I guess decreasing part temperature, results neee to be in + reading, however i got - reading while doing practical.

[@russsorrells1007]

The results of your trial are as expected. Remember that with pressure decay or differential pressure decay, we are measuring pressure change. Any outside influences that effect a pressure change in the part will alter the results. Heat expands the air in the part, therefore increasing the pressure or making it appear not be leaking. Cooling contracts the air in the part, therefore decreasing the pressure in the part. Good work and thanks for sharing your study. Russ

[@captainkc6014]

@@russsorrells1007Thanks for reply. For differential pressure decay method (comparing master and work side)it is obvious increasing the temperature in work side shows negative reading as pressure also increases in that side which push diaphragm towards master side. As you mentioned cooling contracts the pressure , we decreased the temperature in work side only ,reading need to show in positive but it is showing negative,why?