Heart-lung machine (HLM), also called oxygenator pump or cardiopulmonary bypass (CPB) pump, aims to provide extracorporeal circulation (ECC) with maintenance of oxygenated blood flow to the body organs when the device is connected to the arteriovenous system. The HLM is an essential component of open-heart surgery to bypass the circulatory system of the heart and lungs, termed CPB. The main principle is to draw the blood from the major veins (venae cavae) to an oxygenator in the HLM where it is re-oxygenated, and then pumped into the arterial system (ascending aorta). Additionally, the myocardial contractility during CPB can be halted by running a cardioplegic solution containing potassium citrate. The trainer is designed to demonstrate the operation, theory, repair and servicing of heart lung machine equipment that used at clinics & hospitals. The unit given the fault diagnosis so as to facilitate the teaching of trouble shooting techniques. A fault simulator is provided with circuit block diagram of the device for the students to study theoretically and experimentally in order to understand the operation of the device.