Why Need To Close The Discharge Valve Of A Centrifugal Pump During It’s Start-Up?

Why do we need to close the discharge or delivery valve of a centrifugal pump during start-up? 

There is no place such as in Ammonia Process, Basic Process, Chemical Engineering, Chemical Process Technology, Chemical Industries, Lubricant Manufacturing, Manufacturing Industries, Oil and Gas, Petrochemicals, which did not use the centrifugal pump?

https://amzn.to/35PqDjv

https://s.click.aliexpress.com/e/_9hrVYT

# Answer(1) 

=> It is general practice to close the delivery valve of the centrifugal pump during start-up and it is highly recommended for the critical services where the liquid is at boiling/bubble point (Ex. Reflux pump of distillation column). The procedure is to close the valve and start the pump. After this open the discharge valve slowly till 100% which stabilizes the complete system. If this procedure is not followed and the valve is kept 100% open and the pump is started, NPSHa for this will be minimum because of losses due to acceleration during startup. This will result in cavitation of the pump

#️ Answer(2)

=> To minimize the starting torque on the motor.

=> To load the delivery pipe network gradually if it is the only pump that feeds the network.

=> If it is a parallel-connected pump, this method will insure against any reverse flow due to malfunctioning of the upstream side check valve. 

#  There are some centrifugal pumps, called axial or propeller pumps, for which the delivery valve has to be kept open at a min. % as determined by the pump characteristics so, the reason for keeping the delivery valve in the minimum open condition is to minimize the starting torque imposed on the motor.

That’s Why do we need to close the discharge or delivery valve of a centrifugal pump during start-up?

 

Please take a look at the following links:

Question With Answer About Turbine And Compressor In Process Industries 02.

Question With Answer About Turbine And Compressor In Process Plant 01.

What Is Compressor And Compression System? Working Principle Of Compressor

Sewage Or Wastewater Treatment Process.

What Is Strainer? Types of the strainer.

The Steam Turbine, And How It Works?

What Is Rupture Disc, How It Work?

What Is Fire Point, Smoke Point, Freezing Point, Dew Point, Flash Point, Pour Point, Boiling Point, Bubble Point?

Different Type Of Boiler. Boiler Operation And Operation Coefficient.

Pump Cavitation And Prevention.

Pumps & How It Works?

Centrifugal Pump & Troubleshooting.

Let’s We Know About What Is Seal And Types Of Seals.

Personal Protective Equipment (PPE). Types Of PPE.

Safety Measures Associated With Confined Space.

Explosion Hazard And How To Prevent It?

How To Prevent Fire Hazards In The Workplace?

Accident And Its Prevention In Work Place.

Occupational Hazard And Safety Requirements In Industries.

What Is Gas Hydrate? How To Prevent It?

What Is Filter Or Separator? Types Of Filters.

Let’s Know About Plumbing Fittings Or Pipe Fittings.

What Is Lubricant And Properties Of Lubricant?

What is Critical Point, Surge Point, Yield Point, Aniline Point, Triple Point, Triple Point Of Water, Melting Point, Auto Ignition Point?