GMSN horizontal Split-casing centrifugal pump

OVERVIEW——GMSN horizontal Split-casing centrifugal pump

The GMSN Series Split-casing  Centrifugal Pump is designed as a high-flow model with outstanding performance. It features a hydraulic design that naturally balances axial and radial forces, ensuring stable performance, high efficiency, compact structure, low vibration, and high-pressure resistance of the pump body. Installation and maintenance are convenient.

This pump series uses both original and modified impellers, along with trimming techniques, resulting in a broad and comprehensive model range. This allows for high efficiency and the capability to meet any required flow rate and head within the performance range of the model series, providing users with precisely the pump they need for their specific application.

APPLICATION——GMSN horizontal Split-casing centrifugal pump

GMSN Series Split-casing  Centrifugal Pump have a wide range of applications and are widely used in the following fields:

• Municipal Water Treatment Plants
• Steel and Iron Smelting Industry
• Drainage Pump Stations
• Thermal Power Plants
• HVAC Water Circulation Systems
• Industrial Water Supply Systems
• Firefighting Systems
• Shipbuilding Industry
• Refining Industry

ADVANTAGES

GMSN Series Split-casing  Centrifugal Pump offer the following advantages:

• High Flow Capacity: The double-suction impeller design gives this pump series a wider flow range compared to standard centrifugal pumps.
• Energy Efficiency: Equipped with high-efficiency, energy-saving motors, resulting in lower energy consumption.
• Compact Structure: Takes up minimal space, with a significantly reduced axial dimension.
• Low Vibration and Noise: The pump operates with minimal vibration and low noise levels.
• Easy Maintenance: The suction and discharge ports are positioned below the pump shaft centerline, allowing for easy maintenance without the need to disassemble the inlet and outlet pipelines or the motor. Simply remove the pump cover to access all components for repair.
• Versatile Sealing Options: Various sealing types are available to match different operating conditions on-site.
• External Cooling Water Connection: An external cooling water connection can be used to extend the pump’s lifespan.
• Convenient Pipeline Connection: The pump’s inlet and outlet directions can be adjusted according to the site’s piping requirements, making installation more flexible.
• Multiple Drive Options: Typically driven by an electric motor, but can also be powered by other prime movers, such as internal combustion engines (e.g., diesel engines), based on specific needs.
• Long Service Life: The precision of the structure and high-quality mechanical seal with graphite against tungsten carbide or drip-proof packing seals, combined with top-brand bearings, significantly enhance the pump’s lifespan.
• High Efficiency: The GMSN series features advanced hydraulic and structural design, leveraging state-of-the-art computer-aided design software, resulting in high cavitation resistance. Compared to similar domestic products, this series boasts 2-4% higher efficiency, with notably improved cavitation performance, leading to significant cost savings for users.
• Excellent Sealing Performance: The robust sealing structure ensures long-term, leak-free operation.

Assembly and disassembly

Assembling and disassembling theGMSN Series Split-casing  Centrifugal Pump  Follow the following principles

Rotor Assembly Process

1. Assembly of Rotor Components:
   • Sequentially install the following components onto the pump shaft: impeller, shaft sleeve, shaft sleeve nut, packing sleeve, packing ring, packing gland, water deflector, and bearing components.
   • Fit the double-suction seal ring onto the shaft.
   • Finally, install the coupling onto the shaft.
2. Inspection of Rotor Components:
   • Inspect the outer diameter of the impeller’s sealing surface and the outer diameter of the shaft sleeve.
   • The radial runout should not exceed the specified tolerances as indicated below:

   Nominal Diameter (mm)	Radial Runout Tolerance (mm)
   <50	0.03
   50-120	0.04
   120-250	0.05
   250-500	0.06
   500-800	0.08
   800-1250	0.10

3. Mounting the Rotor Assembly:
   • Place the rotor assembly into the pump casing.
   • Adjust the impeller so that its axial position is centered between the double-suction seal rings on both sides.
   • Secure the position by fastening the bearing housing cover with the fixing screws.
4. Packing Installation:
   • Install the packing material, ensuring it is properly positioned.
   • Place the split surface gasket (paper gasket) and cover the pump casing.
   • Tighten the pump cover nuts after securing the tail taper pins.
   • Finally, install the packing gland, but avoid overtightening.
     • If the packing is too tight, it may cause the shaft sleeve to overheat and increase power consumption.
     • If the packing is too loose, excessive fluid leakage may occur, leading to reduced pump efficiency.
5. Post-Assembly Check:
   • After assembly, manually rotate the pump shaft.
   • Ensure there is no rubbing or obstruction, and that the rotation is smooth and even.

Disassembly Process

• Disassembly can be performed by following the assembly steps in reverse order.

Start-Up and Shutdown Procedures

1. Preparation:

1. Before Start-Up:
   • Manually rotate the pump rotor to ensure it turns smoothly and evenly.
2. Water Filling:
   • Close the discharge valve.
   • Fill the pump with water (if there’s no foot valve, use a vacuum pump to prime the pump) to ensure the pump is fully filled with water and no air pockets remain.
3. Pressure/Vacuum Gauges:
   • If the pump is equipped with vacuum or pressure gauges, close the cocks connected to the pump before starting the motor. Once the pump reaches normal operating speed, open the cocks gradually.
   • Then, slowly open the discharge valve. If the flow rate is too high, partially close the valve to adjust; if the flow rate is too low, open the valve more.
4. Packing Gland Adjustment:
   • Gradually tighten the packing gland nuts so that the liquid leaks out in drops. Monitor the temperature rise outside the packing chamber.
5. Stopping the Pump:
   • First, close the vacuum and pressure gauge cocks, then close the discharge valve before turning off the motor.
   • In low-temperature environments, open the drain plug at the bottom of the pump to remove any remaining water to prevent freezing.
   • If the pump will be out of service for an extended period, disassemble the pump, dry all parts, and apply anti-rust oil on the machined surfaces before storage.

2. Operation:

1. Bearing Temperature:
   • The maximum temperature of the pump bearings should not exceed 75°C.
2. Lubrication:
   • Lubricate the bearings with calcium-based grease, filling 1/3 to 1/2 of the bearing housing space.
3. Packing Maintenance:
   • If the packing wears down, tighten the packing gland as necessary. Replace the packing if it is excessively worn.

Installation Procedures 

1. Inspection:

• Check that the pump and motor are free from damage.

2. Installation Height:

• The installation height, combined with the suction line’s hydraulic losses, should be calculated to ensure the available NPSH (Net Positive Suction Head Available, NPSHA) exceeds the required NPSH (NPSHR).

3. Installation Sequence:

1. Positioning:
   • Place the pump on the concrete foundation with embedded anchor bolts. Use wedge-shaped shims to level the pump and lightly tighten the anchor bolts to prevent movement.
2. Concrete Grouting:
   • Pour concrete between the foundation and the pump base.
3. Tightening and Leveling:
   • After the concrete has set, tighten the anchor bolts and recheck the pump’s level.
4. Motor Alignment:
   • Align the motor shaft with the pump shaft so that they are concentric. The permissible misalignment tolerance for the outer diameter of the coupling should be 0.1 mm, and the end face gap variation around the circumference should be within 0.3 mm.
   • Recheck alignment after connecting the inlet and outlet piping and performing a test run to ensure compliance with these tolerances.
5. Coupling Connection:
   • After verifying that the motor’s rotation direction matches the pump’s, install the coupling pins.

4. Piping Support:

• The inlet and outlet piping should be supported independently by brackets. The pump casing should not bear the weight of the pipes.

5. Air Tightness:

• Ensure all connections, especially on the suction side, are airtight to prevent air from entering the pump. Make sure there are no air pockets when assembling the system.

6. Priming:

• If the pump is installed above the suction water level, a foot valve should be installed, or a vacuum pump should be used for priming.

7. Valve Installation:

• A discharge valve and a check valve should be installed on the discharge side of the pump (check valves are optional if the head is less than 20 meters). The check valve should be placed downstream of the discharge valve.

Notes for Pumps with Common Base:

• For pumps with a common base, level the base with wedge-shaped shims between the base and the concrete foundation. The installation principles and requirements are the same as for pumps without a common base.

Start-Up, Shutdown, and Operation of Double-Suction Pumps:

• Follow the detailed procedures outlined above to ensure safe and efficient operation of the GMSN series double-suction pumps.