explain the procedure please.
Here is the answer I gave to another question on centrifugal pump startup. The only difference with a canned pump is the fact that they tend to be much easier to prime due to their geometry.
Assuming the pump is properly primed, The main considerations in starting up a centrifugal pump is the suction and discharge systems, the presence or absence of a check valve in the discharge and its condition as well as the pressure capability of the two systems.
A pump may be pumping against no discharge pressure or it may be pumping against an existing pressure. In the case of no pressure, you need to have the discharge valve closed otherwise you may overload the driver.
If there is existing pressure in the discharge line, there is no concern with over loading either the pump or driver on start up since the pump develops no load until it starts to rotate and build head. If there is a check valve in the discharge and the block valve is open, there is essentially no flow (and therefore no load) until the head developed exceeds the pressure in the discharge line.
The real consideration is having back flow from the discharge to the suction. That is the reason for a properly selected check valve that is properly maintained so it will function as designed. In the case of high pressure pumps where the discharge pressure can exceed the suction pressure to the extent that the suction system could fail it is very important that either the pump be started with the discharge closed or with a properly operating check valve.
One should note that if the pump is multistage, there may be a minimum flow requirement that needs to be worked into the start up procedure to assure there is minimum flow established as soon as possible.
I would assume the only consideration in starting a vacuum pump is the question of maintaining an existing vacuum. In that case you would need as a minimum a check valve in the line to prevent back flow and the loss of the vacuum. Otherwise starting should be similar to starting a centrifugal pump. The final consideration being concern for not overloading the driver on initial startup.
kangro_p
1.Centrifugal Pump:
First of all prime the pump keeping discharge valve closed and ensure that there is no entrapped air.Remember you have to prime the pump in static condition.
Then start the pump with close discharge valve .This is because of the high column head it has to withstand .If you open the discharge valve and start up the pump , then pump has to withstand the high torque which may damage the pump’s motor or prime mover.Be watchful and as soon as the flow is achieved and pressure is there , then start gradually opening the discharge valve.
In case of regenerative turbine pump, you can’t run the pump keeping the discharge valve close.
Bigger size pumps are equipped with star-delta starter ,so initially the pump will start at slow speed and then comes into a design speed to avoid the surge of torque.
During discharge valve closed, pump has to with stand inertia forces and little column head upto discharge valve and hence no danger of motor or pump shaft failure.
In smaller capacity pumps, you can start the pump in circulation
and establishing the pumping gradually open the discharge valve and close the circulation valve as the case may be.
It is essential that you should run the pump at its BEP .
Before doing any operation , keep in mind that you are operating the pump in a fully charged line or operating the the for the first time.
If you operating the pump for the first time , then discharge line needs to be primed by keeping the vent valve or end valve in open condition.
2.Vacuum Pump:
Place pump on flat surface REMOVE Oil Filler cap and the Filter Elements from Combination Exhaust Fitting.
-Pour oil SLOWLY to avoid OVERFLOW AND SPILL. Fill up to the center of the sight glass with INFICON approved HIGH VISCOSITY SHELL TURBO OIL T32/Equivalent.
NOTE: Oil level will rise when the pump warms up & reaches the operating temperature. Check oil level when warm & adjust if required. DO NOT OVERFILL.
-REFIT Filter Elements and Oil Fill cap, ensure the high density (thin) disc is on top. Any oil spill should be wiped with a clean dry cloth.
-REMOVE Cap from one of the inlet ports and turn the Isolation Valve to “OPEN” position.
-Turn power switch ON.
-Let the SHARK run in order to warm-up and when it is running smoothly, turn the Isolation Valve to “CLOSED” position and REPLACE cap on the inlet port.
-Turn power switch OFF and CONNECT to system.
PRIOR TO CONNECTING THE pump TO AN AC/R SYSTEM, REMOVAL OF REFRIGERANT FROM THE SYSTEM IS NECESSARY; DAMAGE TO THE PUMP MAY OCCUR IF
EVACUATION IS STARTED WHILE THE SYSTEM IS UNDER HIGH PRESSURE.
-If a vacuum gauge is being used REMOVE cap from one of the inlet ports, and ATTACH it to the intake.
-Make sure fittings and connections are tight.
-Turn the Isolation Valve to “OPEN” position.
-Turn power switch ON.
-“OPEN” Gas Ballast valve for a few minutes to help bring pump up to its normal operational temperature sooner.
IT IS VITALLY IMPORTANT THAT THE PUMP HAS REACHED ITS NORMAL OPERATIONAL TEMPERATURE (50oC-70oC / 122oF-158oF) BEFORE ANY CONDENSABLE VAPORS ARE PUMPED. FAILURE TO DO THIS MAY CONTAMINATE THE OIL AND DAMAGE THE PUMP.
The pump is NOW READY TO EVACUATE air conditioning and refrigeration systems.
NOTE: If a system leak test needs to be done, it is recommended to keep the pump running after the isolation valve is closed.
Under no circumstances should the fittings on the vacuum pump be used for refrigerant transfer, as damage will occur to the valve.
3.Canned rotor pump:/Magnetic clutch coupling pump:
It is also a centrifugal pump , but it is a seal less pump.
If external bearing cooling is employed , then 1st ensure that.Prime the pump and start as centrifugal pump.
Try the search term in any search engine as following and you will have a lot of clues regarding caned pump:
“seal less pump”
“crane chem pump”
“stork pump”
“Lowrance pump”