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Variable Speed Fire Pump Controllers were invented and released with a UL Listing for fire pump service in 2003 by Master Control Systems, Inc. [1] [2] Paragraph 10.5.5 in the 2003 edition of NFPA-20 recognized Variable Speed as an accepted method for operating the fire pump. Then in the NFPA-20 2007 edition, section 10.10 was added to clarify ...
Booster pumps for household water pressure are usually simple electrically driven centrifugal pumps with a non-return valve. They may be constant speed pumps which switch on when pressure drops below the low pressure set-point and switch off when pressure reaches the high set-point, or variable speed pumps which are controlled to maintain a ...
A variable-buoyancy pressure vessel system is a type of rigid buoyancy control device for diving systems that retains a constant volume and varies its density by changing the weight (mass) of the contents, either by moving the ambient fluid into and out of a rigid pressure vessel, or by moving a stored liquid between internal and external variable-volume containers.
Electronic controllers add greater flexibility in management of boost pressures, compared with the manual controllers. [2] The actuation of an electronic boost controller can be managed by one of two control systems: Open-loop is the simpler option, where control output is merely based on other inputs such as throttle angle and/or engine speed ...
This avoids one of the principal challenges faced by the larger, two-part pumps: maintaining a water-tight seal at the point where the pump drive shaft enters the pump body. Small- to medium-sized circulator pumps are usually supported entirely by the pipe flanges that join them to the rest of the hydronic plumbing. Large pumps are usually pad ...
A means had to be provided, of course, to put the initial charge of water into the boiler (before steam power was available to operate the steam-powered feedwater pump). The pump was often a positive displacement pump that had steam valves and cylinders at one end and feedwater cylinders at the other end; no crankshaft was required.
Piston pumps can be made variable-displacement by inserting springs inline with the pistons. The displacement is not positively controlled, but decreases as back-pressure increases. Another variation is the variable-displacement vane pump, a type that has found usage in motor vehicle automatic transmissions, such as the General Motors Hydra-Matic.
These hoses range in nominal inside diameter from 3.5 to 5.0 in (89 to 127 mm). They are designed to operate at pressures up to about 300 psi (2,070 kPa) for the smaller diameters and up to 200 psi (1,380 kPa) for the larger diameters. The standard length is 100 ft (30.48 m). [12] Forestry hose