In many applications, the pump diaphragm would prematurely fail. The material would fatigue or eventually tear due to the number of cycles under high temperature and prolonged pressure loads. The Hargraves team determined that standard EPDM (ethylene propylene rubber) used in the industry was a major limiting factor in the life of the pumps. EPDM diaphragms typically could expect a life approximately 3,000 hours. This of course was unacceptable to their customers that were requiring life performance under demanding conditions to exceed 10,000 hours.
To eliminate premature diaphragm failures, the Hargraves engineers searched throughout the elastomer industry for a material that would endure these rigorous demands at extended life cycles. They were repeatedly told by the so-called “industry experts” that it could not be done. Undeterred, the Hargraves team took the initiative to develop a high performance diaphragm material on their own. This research project resulted in the development of an advanced EPDM, or AEPDM, a proprietary material configuration that has been tested to last ten times longer than those used by other pump manufacturers. The life of the Hargraves’ AEPDM diaphragms can exceed 20,000 hours depending on the application.
Diaphragm pumps have typically been powered with brush DC motors. Due to the physical contact between the brushes and their commutator, the motor brushes eventually wear affecting its performance and life. Brush motors are designed to last from only 500 hours to 6,000 hours depending on the quality of the motor and how it is used. Hargraves utilizes a proprietary brushless DC motor that is smaller and lighter than that of the competitors. Being a brushless motor, the brushes are inherently removed as a wear item resulting in reliable operation up to 20,000 hours.
Worn brushes on pump motor.
Because of the heavy mechanical loads experienced by the motor of a diaphragm pump, the motor bearings were found to prematurely wear. Proprietary bearing cage design, assembly methods, and materials were employed to reduce radial loading and promote long bearing life.