Predicting and managing control valve noise has long been an important consideration in gas and steam applications, with the dual goals of protecting workers from potential auditory damage and preventing excessive vibration that could destroy equipment and piping, possibly leading to a catastrophic failure.
At first glance, it may seem that a logical way to achieve these goals would be to limit valve trim exit velocity head to a maximum of 480 kilopascals (kPa), and this indeed is how some have addressed the issue. In practical application, however, it is an oversimplified approach that, in many cases, will not produce the desired results. First, it typically requires the use of expensive multi-stage or multi-turn trim designs, which can cost up to 30% more than a simpler solution. More importantly, it also can create a false sense of safety.
This article will explain why the focus should instead be on keeping the valve outlet mach number low. Practical examples will be used to illustrate that:
Even if the trim exit velocity head is kept below 480 kPa, valve noise can be unacceptably high if the valve outlet mach number is high.
Even if the trim exit velocity number is above 480 kPa, valve noise can be kept to acceptable levels — without using costly trim designs — if the valve outlet mach number is kept low.
This paper discusses how portable data logging technology can be used to measure, record and document the performance of geothermal heat pumps, and provides specific case study examples of how the technology is being applied in geothermal system monitoring applications.
This four-page paper includes a brief overview of load cell weighing systems and Coriolis mass flow technologies as well as a discussion of special considerations and benefits that each technology provides.
Designers who understand and can take advantage of the differences between fluid power and traditional electromechanical power can build machines that produce higher quality output with lower lifecycle costs. This white paper suggests that care must be taken, however, in selecting and sizing the hydraulic system elements and in tuning the motion controller for optimal performance.