Revolutions Per Hour (RPH): Understanding Slow Rotational Speed Measurements
Revolutions per hour (RPH) is a unit of frequency that measures the number of complete rotations made in one hour. Although the SI derived unit of frequency is the hertz (Hz), revolutions per hour provides a practical way to describe slow rotational speeds without using very small decimal values.
What Is Revolutions Per Hour?
Revolutions per hour measures how many complete rotations an object performs in sixty minutes. It is particularly useful for equipment and natural processes that rotate too slowly to be conveniently expressed in hertz or revolutions per minute.
This unit is commonly used for slow-speed motors, industrial conveyors, environmental monitoring systems, astronomical observations, and mechanical equipment operating over extended periods.
History of Revolutions Per Hour
Time-based rotational units have been used since the development of mechanical clocks and rotating machinery. While revolutions per minute became the standard for high-speed systems, revolutions per hour emerged as a practical alternative for measuring much slower rotational frequencies in engineering and scientific applications.
Current Uses of Revolutions Per Hour
Revolutions per hour is used in industrial automation, process engineering, environmental monitoring, astronomy, and maintenance of slow-speed rotating equipment. It is also useful for reporting the operating speed of devices that complete only a few rotations each hour.
Revolutions Per Hour Conversion
One revolution per hour is equal to:
- 0.000277777777777778 hertz (Hz)
- 0.0166667 revolutions per minute (rpm)
- 24 revolutions per day (rpd)
- 0.000277778 revolutions per second (rps)
You can use ChangeUnit to convert revolutions per hour to hertz, revolutions per minute, revolutions per day, and many other frequency units.