I usually use dimensional analysis and I can't remember how to set it up. 1. The order is to infuse 1000 units heparin per hour from an available solution strength of 25,000 units in 500 ml D5W. Calculate the ml/hr rate. 2. A solution of 25,000 units heparin in 500 ml D5W to infuse at a rate of 1200 units per hour. Calculate the ml/hr rate.