# Guide to UV Measurement

# Line Speed/Dwell Time

The line speed/dwell time is important because it controls the amount of time that your product is exposed to UV.

With a conveyor, faster line speeds mean less time under the UV system and a lower energy density. If all other variables stay the same, increasing the line speed would reduce the number of joules. Slower speeds mean more exposure to UV and a higher energy density or number of joules. For an example, click here.

Operators need to test and confirm their line speed. Doubling the line speed controller from a setting of ‘two' to ‘four' does not mean that you line speed will double. For an example, click here. Use a digital tachometer or stopwatch to confirm that your belt speed is where it belongs.

If the energy density (joules/cm² ) can be established at line speeds that are easy to measure and within the sampling parameters of your radiometer, estimates can be made for what the energy density will be at different speeds.

Use the equation Ex= Ey x Vy/Vx where Ex is the energy density that you want to estimate. Ey is the known energy density, Vy the known line speed and Vx the new line speed.