Form V372, Rev. 12
- 4 -
12/18, ECN4334
Total Rotamix
TM
flow is determined in consultation with Vaughan Co. Sales Engineering. The total flow
is calculated based on your storage tank (or digester) volume and consideration of your tank geometry.
Once you know total system flow, you can determine best sizing for suction and discharge piping.
Vaughan Co. will help you with piping sizing recommendations.
Nozzle sizing for the nozzle assemblies is also determined at the beginning of the Rotamix
TM
project in
consultation with Vaughan Co. Proper sizing for the nozzles is critically important in making the system
work efficiently.
Follow all confined space entry procedures when entering an enclosed tank.
Nozzle aiming is performed once nozzle assembly installation is complete but before the storage or
digester tank is closed up. Proper nozzle aiming is critically important and is performed by your
Vaughan Co. representative. Please contact your representative to schedule this very important
operation before closing the digester or storage tank.
Finally, location of the nozzle assemblies within the digester is determined in consultation with Vaughan
Co. In a cylindrical tank (such as a digester) the floor-mounted nozzles are typically mounted on a circle
whose diameter is defined by Vaughan Co. based on the diameter of your storage tank. Also, the
nozzle angles are determined by Vaughan Co. The positioning and angles of the nozzles in your
digester or storage tank are defined on a Rotamix Nozzle Location Plan drawing specific to your
project. This drawing will always be included in the custom Installation, Operation and Maintenance
Manual for your particular Rotamix system.
Vaughan Foambuster:
The Vaughan Foambuster is a patented nozzle and splash plate combination that sprays sludge
droplets over a large area at the upper surface of a digester to break down and suppress foam. In some
cases, digester mixing systems are purchased with the addition of the Foambuster because of the risk
of foaming, particularly in activated sludge plants. The Foambuster nozzle must be mounted above
liquid level. Only a few inches of distance is enough to allow the Foambuster to work. Also, the
Foambuster needs about 4 ft. of headroom above the height of the nozzle to allow the spray to cover as
much of the tank surface as possible. The Foambuster works best with a fixed cover. Finally, the
Foambuster is designed to be aimed radially inward toward the center if the Foambuster if located near
the outer walls, or aimed radially outward toward the outer walls if the Foambuster is located at the tank
center. When the Foambuster is used with the Rotamix system, Rotamix rotates the liquid in the tank
below the Foambuster. In this way, one Foambuster can cover all the surface area of the tank as it
rotates below the Foambuster.
Vaughan Co. recommends that the Foambuster operates whenever the Rotamix system operates. By
taking this approach, if foaming should occur, the Foambuster will always be operating to keep the level
of foam broken down and under control. If foaming is allowed to take place when the Foambuster is not
operating, foam may adhere to the tank walls, preventing the surface from rotating. If the upper surface
does not rotate, the Foambuster will not be effective at controlling foam over the entire upper surface.
System Venting:
Explosions can kill or injure! Mixing may liberate gases of decomposition which are highly
flammable or explosive. Do not use an open flame or non-explosion-proof equipment in areas
where gas is present. Follow all plant safety procedures for hazardous areas.
Sludge pumping systems are likely to generate gases of decomposition and these gases are likely to
collect in either the suction piping or in the chopper pump casing. Should this occur, the pump would
not work properly when started, since the impeller, when rotating, will collect gas and not be able to fill
with the sludge to be pumped. So gas buildup in the system may keep your pump and Rotamix system
from working properly. This can be particularly troublesome if your system operates intermittently. Gas
binding is also much more common if your pump has other than a top discharge on the pump casing.
