A large portion of the population has no idea what a leak tester is, or the role it plays on products used every day. Have you ever stashed a few extra packets of sugar in your bag only to find a heap of the sweet stuff all over your things?

Let’s face it everybody wants to get more done with less. Whether we are talking staffing, robots, AI or automated assembly lines – the more you can do faster, the better. The same, of course goes for leak testing. As it’s our business, we know that for some (many) manufacturers,

Leak Testing Compensation and Calibration

What is Comp & Cal?

In leak testing you’ll frequently come across the expression “compensation and calibration “or “comp and cal”. This week we will explain what we mean by it and why it is important.

One of the challenges in leak testing using air to fill or pressurize a part is the “adiabatic effect”. An adiabatic effect is one in which heat is not transferred into or out of a system yet a change in temperature occurs. The change is due to work being done on the system’s surroundings. A good example is that of a piston compressing a gas in a cylinder. Did you notice how your bicycle tire pump gets hot when you inflate the tire?

The adiabatic effect occurs when the air pressure in a volume is increased. Remember the calculation (P1xV1)/T1 = (P2xV2)/T2. As the pressure is increased, the number of molecular collisions also increases because the distance between the molecules decreases. The collisions create friction and the result is heat. We learn early in life that heating the air in a closed vessel increases the pressure. When the pressure ceases to increase or the work stops the air molecules slow down and the number of collisions decreases. This in turns leads to cooling and a drop in pressure. If we start to measure the leak rate immediately when we stop filling the part, the small drop in pressure from the reduced molecular activity will resemble a leak and we might get a false result.