SCANJET model SC 15TW is a tank cleaning machine specially developed for the cleaning cargo and slop tanks onboard Chemical and Product carriers and other applicable tanks. The size, construction, and cleaning requirements of these tanks are design criteria, which have been evaluated prior to installation. The SC 15TW could be used as a fixed installed machine as well as for portable use.
The cleaning procedure will start by opening the valve for cleaning media. The water flow will pass over a turbine inside the machine and the nozzles will rotate creating a cleaning pattern inside the tank. When the cleaning procedure is finalized the valves are to be closed.
Installation of a SCANJET Tank cleaning machine
The SCANJET Model SC 15TW should be installed in a vertical position. For fixed installed machines it is recommended to install a strainer close to the machine in the supply line in order to avoid any particles clogging the machine. The portable is fitted with strainers at the inlet.
- Always flush the supply line prior to starting the machine.
- Don’t use the nozzles as handles for turning the machine onto the threaded coupling, this will damage the gears inside.
- When tightening the rubber hose for the thread on the machine, use a hookspanner to counter hold the upper adapter flange.
|The use of a tank cleaning machine may cause static electricity why measures must be taken in order to avoid sparks and possible explosion by heaving the tanks inert at the time of cleaning.|
Working Principle of SCANJET Tank cleaning machine
The cleaning media flows through the machine to the nozzles and then out in the tank.
The gearbox is media-lubricated and does not require any oil or grease.
The machine and nozzles will rotate and will clean the tank in a pattern shown below. The machine body rotates inside the tank and the nozzle house will also rotate.
The rotating nozzle will create a cleaning pattern as per below on the vertical tank walls. After one cycle will a cleaning pattern be created as per figure 1. After four cycles will the pattern be completed as per figure 2. After this, the pattern will be repeated.
A full pattern is created when the main body has rotated 47 turns. With a rotation speed of 2.5 RPM will a full pattern take approximately 18.8 minutes. Note that the time is depending on the actual setting of the turbine and water pressure.
Supply data: Scanjet SC 15TW is operated with a supply of cleaning media at a flow of approximately 7-24 m3/h and at an inlet pressure of 0.6-1.2 MPa.
Rotating Speed: The rotation speed can vary between 2-4 revolutions per minute depending on the supply data and turbine settings.
Weight: Machine approximately 9.2 kg
Material: According to order (AISI 316/ Peek).
Performance data: The table below shows the approximate flow and jet length for each combination of inlet pressure and nozzle diameter 2 x Æ8 mm.
General Installation Data
Operation of SCANJET Tank cleaning machine
The machine will start automatically when there is a supply of cleaning media to the machine. The machine is self-lubricated by means of the cleaning media and self-draining through a hole in the bottom plate.
Calculation of cleaning time
Calculation of cleaning time for a full Pattern
The cleaning time depends on the following:
Rotation speed of the Main House: A (rev/min.)
Number of rotations for full Pattern: 47 (turns)
Cleaning time: D (minutes)
Cleaning time D=47/A (min)
Example 1: The Main Body rotates with 2.5 turns per minute. (Checked with a wristwatch when looking at the machine). How long time does it take to create a first cleaning patter in the tank?
A first pattern is created after 1 cycle!
Cleaning time D=47/2.5/4 = 4.7 minutes.
After an additional 4 x4.7 = 18.8 minutes will a full cleaning pattern be created.
Calculation of cleaning time for getting out a certain amount of cleaning media (prewash).
- The total flow Q (m3/h) through the nozzles at the specific pressure used is taken from the table above. The total flow in the tank is then calculated by adding the flow from all machines used at the same time in the tank.
- Needed amount of washing media R (m3) calculated as per Prewash Regulations or other.
- The time T the machine must be in operation is then calculated as:
T=R/Q x 60 (min)
Prewash rules give that 6 m3 of cleaning media should be used.
We have a tank with two (2) machines having 8 mm nozzles and will operate the tank cleaning machine at 12 bar pressure.
How long time should we operate the machine?
Machine data at the table above that at 12 bar and 8mm nozzles will give a flow of 17 m3/h per machine. The total flow will then be calculated by adding both machines giving a total flow in the tank of 34 m3/h.
Needed time T=6/34 x 60 = 10.5 min
The rotating speed for the machine could be adjusted by changing the position of the conical turbine on its shaft. The speed will increase when lowering the turbine and vice versa.
Procedure to change the speed
- Remove the inlet flange (A) by unlocking the locking plate (B) and remove the bolts (C)
- Loosen the contra nut (D) with key No 17 and Allen key No 4.
- Turn the turbine to desired position and lock the contra nut.
The correct speed should be between 2-4 RPM ideal is 2.5-3 RPM be careful not to screw the turbine too far down in the cone. This may cause the machine to stop because the turbine is touching the cone.
Changing bearings and gears
Change of bearings is recommended after 250 service hours.
Change of gears is recommended after 500 service hours.
Depending on cleaning fluid and the environment the wear of the moving parts in the machine can be different.
To change the bearings in the gearbox the following procedure should be followed.
- Open the bolts (A) and part the machine
- Check and inspect Bearings (B, C and D) and change if needed.
- Check and inspect gears (E) and change if needed
- When re-tightening the screws use Loctite 222 medium
If the machine does not run:
In order to check and get the machine in operation, carry out the following inspection:
- Check that there is no dirt in the strainer, around the turbine or the stator. Particles can be stuck in the turbine if the supply line contains a lot of rust. Always flush the supply line before starting the cleaning machine.
- Start the machine by opening the inlet valve slowly. Check that the pressure is correct!
If the Machine runs with wrong speed:
Change the turbine speed as explained before and check pressure and flow.