Design and development of mechanical test bench for testing and calibration of multiple blood pressure measuring devices.

Blood pressure (BP) measurement is an important physiological parameter for human health monitoring, which plays a significant role in the diagnosis of many incurable diseases. However, due to inaccuracies in the different types of BP measuring devices, the calibration of these BP measuring instruments is a major concern for a medical practitioner. Currently, these devices' calibration, testing, and validation are performed using rigorous methods with complex clinical trials and following the available documentary standards. This article describes the design and development of an indigenous mechanical test bench (MTB) system for the testing and calibration of multiple BP devices, as per International Organization of Legal Metrology (OIML) recommended documents e.g., OIML R 16-1 and OIML R 16-2. The developed system can test and calibrate 20 BP devices, simultaneously. The traceability of the developed MTB is established by performing its calibration against the Air Piston Gauge, a national primary vacuum standard. The estimated expanded measurement uncertainty evaluated is found to be ±0.11 mmHg, which is almost one order better than the measurement uncertainty required for the test and calibration of BP measuring instruments as per standard. The MTB has successfully been used to test and calibrate several BP measuring instruments. The data of one such device is reported herein as an indicator of the performance process. The calibration of these BP measuring instruments was performed in the static mode, and the estimated expanded measurement uncertainty was found to be ±1.25 mmHg. The developed MTB system would prove to be an excellent instrument for calibration laboratories, hospitals, regulatory agencies, and other users to test and calibrate 20 BP measuring devices simultaneously and cost-effectively.

Development of hydraulic cross floating valve.

This paper describes the design, simulation, development, and analysis of a Cross Floating Valve (CFV), an important instrument used in a cross float or pressure calibration system of pressure balances (PBs) to make the calibration process easy and time efficient. The design aspects of the CFV include the selection of proper materials and modeling of various necessary components of the CFV. For the piston design, 5 different materials, SS304, SS316, Aermet 340, SS440C, and AISI17-4PH were used. After the design, simulation studies were carried out using the ANSYS (Workbench R15.0) software to understand the behavior of stress, strain, and deformation. Out of the 5 materials thus used, the values of the factor of safety of 2 materials (SS304 and SS316) were found to be below expectations and hence were not used in the fabrication process. Among the rest of the 3 other materials (AISI17-4PH, SS440C, and Aermet 340) having a factor of safety within the expected limits, Aermet 340 was also ignored because of its high cost. Finally, AISI17-4PH and SS440C were used to fabricate the piston, the most important and critical component of the CFV. The final CFV thus developed was tested for its performance in the cross floating experiments with 2 different sets of PBs. The results thus obtained show that the use of CFV reduces the calibration time considerably which is approximately 30% (average time of increasing and decreasing orders of pressure) from the time taken in performing calibration without using CFV, which is a significant achievement.