Was wondering how long would 48oz of canadian beer last in urine for a 57 yr old man that weights about 170?

I'm assuming you're talking about EtG testing. Usually, the alcohol wears off within 80 hours. Granted, if you've had a really long night of drinking, it can go up to 120. One beer (a large one, however) should dissipate within 80 - 100 hours.

Alcohol stays in your system at the rate based on many factors, like sex, age, weight, height, since beer, wine, liquor has basically the same amount of alcohol, the safe bet is to assume it takes approximately, (1 drink), 1/2 oz of alcohol per hour (to 90 minutes), for most people to metabolize.