What is a Jet Assist Dump?
Jet Assist Dump
Additional methods might be desired to improve the off-loading rate of gravity dumps. These methods include a jet assist or a pneumatic pump. Control should be from the pump operator's position. Two types of jet assists can be used, one directed into the throat of the gravity dump and the other a peripheral jet system.
Figure A.18.5.2.2(a) shows how the traditional jet is installed. A smooth-tipped “jet” nozzle is supplied by a pump that is capable of delivering at least 250 GPM (1000 L/min) at a gauge pressure of 150psi (1000 kPa). Jet nozzles range in size from 3⁄4 in. to 1 1⁄4 in. (19 mm to 32 mm). The diameter of the tip will be determined by the capacity of the pump being used and the diameter of the discharge piping and dump valve.
The UPF standard jet assist designs can be found here.
INSTALLATION, JET LINE (1 1/2" SIZE) (GENERIC)- 980-0020.PDF
INSTALLATION, JET LINE WITH OFFSET PIPING (1 1/2" SIZE) (E-ONE) -980-0021.PDF
INSTALLATION, JET LINE WITH OFFSET PIPING(1 1/2" SIZE) (GENERIC) -
980-0022.PDF
INSTALLATION, JET DUMP WITH VELOCITY TUBE
(6" W/ 1 1/2" JET) -
980-0023.PDF
Figure A.18.5.2.2(a) Traditional Internal Jet Dump.
The peripheral application of jet assist nozzles has proved highly effective. This approach utilizes two or more jets installed in the sides of the discharge piping just outside the quick dump valve. In addition to the reported discharge advantages of peripheral discharge streams, the externally fed system is easier to plumb and has fewer maintenance problems. The jets, installed 25 degrees to 30 degrees from the piping wall, contact more surface area of the discharging water, thereby increasing water discharge efficiency. Because the water is drawn through the dump valve, less turbulence is created, and the eddy effect often present with traditional in-line jets is overcome. Nozzles made by welding reducer pipe fittings work very effectively as jets. Flow rates of 2000 GPM (8000 L/min) have been obtained using a 300 GPM (1100 L/min)pump to supply two ¾ in. (19 mm) nozzles in a 6 in. (150 mm) dump valve configuration. FigureA.18.5.2.2(b) shows a diagram of a peripheral jet assist arrangement.
Figure A.18.5.2.2(b) Peripheral Jet Assist Arrangement (Top View).