Vacuum systems are used routinely in industry to transport liquid products such as water, slurries, or sludges, as well as dry products. These vacuum systems may be truck-based, or alternatively, on a portable platform such as a trailer or skid. A common question is how far can product be transported, and how close the vacuum unit must be located to the job. This paper answers that question for moving liquid products with vacuum systems based on Liquid Ring pumps.
For liquid products, it does not make a difference how far your horizontal run is (up to 400-500 feet) as long as you use good seals and gaskets to prevent losing vacuum. Make sure you do not have any kinks or additional (unnecessary) lifts or dips in the hose. It needs to be as straight as possible on the flat runs. Use slow 90 degree radius turns. Bends in lines reduce loading rate significantly. Your vertical lift is going to be the hardest part of this process. No machine will lift a solid column of water over ~30 ft. You can make very high lifts (over 100′) vertical if air is allowed to enter the column. Make certain that your hose is not buried in the product for extended time….the system needs to gulp air.
You cannot burn up a liquid ring vacuum systems by burying the hose in the product; it will only make hot water in the water tank. When that water eventually evaporates you will lose your vacuum. When you add water back to the tank your vacuum will return.
Hard pipe will increase your flow greatly by reducing friction losses. Maybe you cannot use it, but if it is possible use it. (Hard pipe is typically Schedule 80 PVC, glued on straight runs, flanged cleanouts on any slow radius 90°s, threaded pipe end for flexible suction hose). Downhill works best if you are sucking into a container. If there is a possibility to do this, do it.
In general, larger diameter hoses provide greater vacuum efficiency and higher loading rates. Changing hose diameter along the length of the suction hose can be a problem. The air velocity is directly dependent on hose diameter, and a variation of airspeed can lead to a pluggage on solid products.
Hose of 4″ diameter can be handled by one man. Hoses of 6″ diameter require frequent breaks or tag-teaming by two men. A better alternative is to use a wheelbarrow or brooms or squeegees to move the product to the hose. It is also possible to Tee off the intake and have two working hoses at the same time, in the right situation. Wands are available for the hose end to facilitate product pickup, and often makeshift handles are fashioned out of broomsticks and duct tape.
For solids, a 6″ hose can generally handle 2″ maximum diameter size particles, a 4″ hose can handle 1″, and a 2 ½” hose can handle ½” maximum particle size.
As pointed out, hard pipe is best for reducing friction losses. If you don’t have hard piping, next best is smoothbore hose. Corrugated polyethylene hose is lightweight and easier to handle, but long lengths of corrugated hose can dramatically reduce rates. Most of your hose length should be hard pipe or smoothbore rubber hose, with only the last section of the working end (<30′) being lightweight corrugated hose.