"' Truck and trailer-mounted sewer jetters "'used by municipalities and larger service companies benefit from the high hydraulic horsepower delivered by powerful displacement pumps and so can remove tree roots and other solid obstructions.
42.
Thereafter, research into the partial vacuum lapsed until 1850 when August Toepler invented the Toepler Pump and Heinrich Geissler invented the mercury displacement pump in 1855, achieving a partial vacuum of about 10 Pa ( 0.1 Torr ).
43.
Some early forms, such as the Hall system ( which dates back to 1896 ), used a fixed displacement pump and a variable displacement motor, and were designed to provide robust variable transmission for early commercial heavy motor vehicles.
44.
A "'flexible impeller pump "'is a positive-displacement pump that, by deforming impeller vanes, draws the liquid into the pump housing and moves it to the discharge port with a constant flow rate.
45.
While a 4-stroke engine uses the piston as a positive displacement pump to accomplish scavenging taking 2 of the 4 strokes, a 2-stroke engine uses the last part of the power stroke and the first part of the compression stroke for combined intake and exhaust.
46.
A "'rotodynamic pump "'is a kinetic machine in which energy is continuously imparted to the pumped fluid by means of a rotating impeller, propeller, or rotor, in contrast to a positive displacement pump in which a fluid is moved by trapping a fixed amount of fluid and forcing the trapped volume into the pump's discharge.
47.
:: : : That's helpful, but I'd strongly prefer a centrifugal or axial pump-- the downstream setup is a packed-bed reactor which I expect will " routinely " clog up ( in fact, it will be set up for batch operation only due to the product forming a crust and blocking the flow ), and in such a setup a positive-displacement pump of any sort could be positively dangerous.
48.
I wonder why internal combustion engines use centrifugal pumps for the fuel delivery system . this gives us the headaches of priming the pumps . isnt it possible just to use a "'positive displacement pump "'for fuel delivery since it needs no priming ? why prefering the centrifugal ones . moreover i understand centrifugal pumps do not develop good pressure heads .-- Chiwaye 13 : 48, 4 August 2006 ( UTC ) Chiwaye, 04 / 08 / 06
49.
A "'sewer jetter "'is composed of a controlled high-pressure water source such as a pressure washer or reciprocating displacement pump, a flexible high-pressure line ( called a jetter hose which connects the high-pressure engine to the mini-reel ) of up to hundreds of metres ( several hundred feet ) in length, the Mini-Reel ( a hose reel which can be taken a distance from the engine ) and a nozzle that uses hydraulic force to pull the line into sewer drains, clean the sides of pipes, and flush out residue.
