A Universal Method for Priming Pumps
Abstract Generated abstract
This paper addresses reliable priming methods for mine drainage pumps, especially where recessed pump chambers are unavailable or impractical. It compares existing approaches, including recessed chambers, service tanks with hydraulic regulators, siphon priming, accumulator tanks, discharge-pipeline transfer, and vacuum pumps, noting operational drawbacks such as cavitation risk, air ingress, loss of water, sealing requirements, and reduced suction lift. The author proposes a universal arrangement using a small service tank kept filled by an auxiliary pump, with level relays for automatic replenishment and control. The method is presented as applicable to both main and auxiliary drainage installations and as allowing simplification of automation circuits when pumps remain continuously filled with water.
Full Text
UNIVERSAL METHOD FOR PRIMING PUMPS
B. M. TITOV
(Presented to the scientific seminar of the Department of Mining Electromechanics)
The simplest and most reliable method of priming pumps is the recessing of the drainage chamber. With this method of priming, a constant head of water is created on the first impeller, which eliminates the possibility of cavitation and of air being drawn in through the gland on the suction side of the pump. Unfortunately, however, the recessing of pump chambers is not provided for by the Safety Rules and is practically feasible only at newly constructed drainage installations.
In non-recessed pump chambers, when water is available at a higher level, priming of pumps from a service tank with a hydraulic regulator should be used. The siphon method of priming, used when water is taken at a height of not more than 60–70 m, creates, when the pump is stopped, a constant additional pressure on the glands and the suction pipeline, and therefore has no advantages over priming pumps through a service tank with a hydraulic regulator. To supply water from the upper level to the service tank, the pressure pipelines of the pumps should be used [1]. This reduces pipe consumption and facilitates starting the motor with the valve on the pump discharge pipeline open.
If it is impossible to recess the pump chamber, or if there is no water at higher levels, it is possible to recommend (Fig. 1) the use of a service tank with a capacity of 1 m³, with automatic replenishment of it, kept constantly filled, from the same service tank by an auxiliary pump with a capacity of 20–25 m³/hour. This method of priming pumps is universal and quite reliable.
Priming pumps by means of accumulator tanks, by transfer of water from the discharge pipeline, and by a vacuum pump is not reliable, since when air enters the accumulator tank self-suction does not occur, water rather often leaves the discharge pipeline, and vacuum pumps require very careful sealing of the pump installation. In addition, the use of accumulator tanks reduces the useful suction lift of the pump.
The proposed method of priming pumps is applicable both to main and auxiliary installations. In transfer (auxiliary) drainage installations, at the drain from the pipeline, a small priming tank with a level relay should be installed, analogously to Fig. 1,
automatic starting and stopping of the pump should be carried out by means of water-level relays in the receiving well and in the priming tank, connected in parallel with one another.
Priming control in automation circuits, when the pumps are constantly filled with water, can be eliminated.
Fig. 1. Supply tank with automatic replenishment by a continuously primed auxiliary pump.
1—auxiliary pump; 2—pipelines to the discharge nozzles of the main pumps; 3—overflow drain; 4—level relay; 5—switch for changing the circuit from automatic to manual control.
LITERATURE
- B. M. Titov. Starting gate valve and hydraulic-shock damping valve for automation of mine drainage installations. Design and Construction of Coal Enterprises, No. 2, Ugletekhizdat, 1959.