Horizontal pump - pump with its shaft in horizontal position. See axially-split .
Hot oil pump - pump handling oil in 300-850 degrees Fahrenheit typical range.
Hot work - work that involves cutting, grinding, welding, and similar activity that produces arc, spark, or open flame. Hot work requires a permit and shall be done by trained and authorized personnel only.
Hydraulic drawings - engineering drawings containing the design and dimensions of pump components such as the suction bay, suction bell, impeller, volute, and crossovers, etc., that form the internal liquid passageway of a pump. They are different from machining drawings.
Hydraulic power recovery turbine (HPRT) - a turbo-machinery designed to recover energy from a liquid stream by breaking down its high pressure to a lower pressure level, such as a reverse-rotating centrifugal pump specifically designed to operate as a hydraulic power recovery turbine.
Hydraulic re-rate - Hydraulic re-rate refers to changing the rated operating conditions of a pump by modifying its hydraulic parts, or components, to effect the change. The rated conditions can be the machine’s operating capacity, differential head, and speed; the liquid's specific gravity, viscosity, temperature, suction pressure, and vapor pressure; or the site's net positive suction head available (NPSHA).
Hydrodynamic bearings - bearings using the principles of hydrodynamic lubrication, such as sleeve bearings and tilting-pad bearings. Anti-friction (ball) bearings are not considered hydrodynamic type.
Hydrogen sulfide (H2S) - a highly toxic gas present in hydrocarbons. H2S can cause serious injury, or death, even at very low concentration. Pumps handling liquid with H2S requires special construction.