Comments for Chemical Engineering GATE Exam

Comment on How To Start A Canned Pump , Centrifugal Pump And A Vacuum Pump? by kangro_p

kangro_p — Sat, 30 Jan 2010 06:39:26 +0000

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”

Comment on Are There Any Centrifugal Pump That Can Handle Gases With Liquids? by alpha b

alpha b — Fri, 29 Jan 2010 22:25:39 +0000

The laws of physics haven’t changed from the past to the present.
Centrifugal pumps can handle small amounts of gas but the ability is limited depending on the liquid, the configuration of the pump and the piping.
The small amounts of gas are essentially entrained in the liquid and move with the liquid and do not accumulate in the pump case. In-line vertical pumps and side discharge pumps seem to be able to handle slightly more gas than other pumps.

Comment on How Do You Calculate The Power Of A Centrifugal Pump From Head And Discharge? by wache_it

wache_it — Fri, 29 Jan 2010 15:25:32 +0000

http://www.google.ca/search?hl=en&q=How+…
you will mostlikely find the answer there

Comment on What Happens When Discharge Of Centrifugal Pump Connected Directly To Suction And Valves Fully Opened? by abdulkha

abdulkha — Fri, 29 Jan 2010 07:04:03 +0000

The fluid goes around in circles.

Comment on What Happens When Discharge Of Centrifugal Pump Connected Directly To Suction And Valves Fully Opened? by Ecko

Ecko — Fri, 29 Jan 2010 06:58:23 +0000

pump will get hot and break down after some time.i work on ship and we have 100’s of pumps on a big ship

Comment on What Happens When Discharge Of Centrifugal Pump Connected Directly To Suction And Valves Fully Opened? by huscafat

huscafat — Fri, 29 Jan 2010 06:40:52 +0000

The water gets hot. Probably very hot. Not a very meaningful thing to do.

Comment on What Happens When Discharge Of Centrifugal Pump Connected Directly To Suction And Valves Fully Opened? by alpha b

alpha b — Fri, 29 Jan 2010 06:29:41 +0000

It depends by many circumstances, but mainly if the pump is at a higher or a lower altitude on related to the liquid.
By understanding it better, see the liquids Leiden law of kinetics.
Hahaha!

Comment on Effect Of Delivery Pipe Diameter Of A Centrifugal Pump Delivery Time, Flow, Height Used For Water? by oil field trash

oil field trash — Thu, 28 Jan 2010 22:52:17 +0000

Turbine Controls
Gas & Steam Turbine Control Systems Design, Manufacure & Installation

Comment on Effect Of Delivery Pipe Diameter Of A Centrifugal Pump Delivery Time, Flow, Height Used For Water? by Rajib D

Rajib D — Thu, 28 Jan 2010 22:46:07 +0000

Any time you increase the diameter of a pipe on the discharge of a centrifugal pump you reduce the amount of friction loss and the total head the pump must pump against. With lower head the pump will then pump at a higher rate.
The degree to which this change will improve the pumping time is dependent on the length of the replaced pipe, the flow rate from the pump and the pump performance curve. If you have this information then you can estimate the improvement in pumping time.

Comment on Is A Turbine Pump Considered A Centrifugal Pump Or A Positive Displacement Pump? Explain? by o dog

o dog — Thu, 28 Jan 2010 15:31:19 +0000

why don’t you look it up yourself? That’s a question right out of your homework assignment.