Lag Time Calculations

If you are talking about flow rate for a gas or a liquid, you can use a dual channel dynamic signal analyzer, and use the cross correlation function to measure the delay. You would need a pair of transducers (perhaps vibration sensors) to feed the two electrical signals to the analyzer.

I would bet that you could buy such an analyzer on Ebay for a very good rate.

Refer EEMUA 138 ,

BTW these Information shall be supplied by vendor in their Technical Submittal,

Regards

Jose

I need a formula for e.g if the distance from process sample take off point to analyzer is about 100 metre and tubing size is 6 mm with fast loop flow 100 l/h and the sample flow to analyzer at 30 l/h pressure at 0.5 bar assume process pressure a 4 bar. In this case let say we are talking about liquid, can someone tell me what will be the lag time?

Hi there,

Are you talking about the lag time based on your measuring response?

Either way ou would need to know the viscoscity, density and velocity of the medium you want to measure. When you have these you can work out your lag time.

Regards,

Craig

Lag time = pipe length divided by mean velocity.