A Bahraini researcher has discovered a method to detect leakage from the diaphragm of a control valve actuator, reported the Bahrain Tribune newspaper.
Mohammed Sharif also established the effects of three common faults on the performance of the valve, its actuator and the downstream flow rate, said the paper.
Sharif presented his research at the International Conference on Condition Monitoring and Diagnostic Engineering Management (COMADEM 2000) which took place in Houston, Texas.
The technical paper was entitled, “Condition monitoring of pneumatic valve actuators: Multiple fault detection and analysis of effects on process variables”.
“I wrote the paper after conducting a well-structured diagnostic test on an industrial control valve and a spring and diaphragm-type actuator,” he told the Tribune.
A spring and diaphragm-type pneumatic actuator were used in particular for the research program since this type of actuators is commonly used in many industries and is regarded as industry standard.
“The diaphragm is used due to many factors like it being very reliable, easy to maintain and safe for the environment where flammable items are produced,” he said.
“It also provides sufficient speed and thrust for most industrial applications,” he added.
“The spring provides the fail-safe action so that if the air supply fails, the control valve either closes or opens and compressed air (source of energy) is easily available and transportable.”
He said a standard diaphragm is made of nitrite (reinforced nylon) which is a very flexible and airtight material. “However, its flexibility deteriorates and hardens up due to the heat from the working environment. When this happens, small holes and cracks are developed in the diaphragm, which may lead to a total split of the diaphragm if the holes are not detected soon.”
The diaphragm splits, the actuator fails to operate and consequently, it will be very difficult to control the process.
“This forces the operators to close down a section of the production line in order to repair or replace the actuator. The stoppage of the process could cost a considerable amount of money due to the loss of production and maintenance costs,” Sharif said – Albawaba.com
