The Johnson Pump TopGear GP is a series of rotary positive displacement pumps with internal gear, primarily constructed from cast iron. These pumps are designed for various applications, including the transport of liquids, and feature heating/cooling jackets (for steam), multiple sleeve bearings, and a range of gear and shaft materials. Some models also include a mounted relief valve and electrical heating.
Function Description
The TopGear GP pumps operate on the principle of internal gear positive displacement. As the rotor and idler gear unmesh, an underpressure is created, drawing liquid into the newly formed cavities. The liquid is then transported in sealed pockets to the discharge side, with the pump casing walls and crescent creating a seal that separates the suction from the discharge side. When the rotor and idler gear mesh, the liquid is pushed into the discharge line. Reversing the shaft rotation will reverse the flow through the pump.
These pumps are self-priming when sufficient liquid is present to fill the clearances and dead spaces between the teeth. A safety relief valve is crucial for protecting the pump against overpressure by limiting the differential pressure between suction and discharge. This valve reroutes media back to the suction side when a specified pressure level is reached. It protects against overpressure in one flow direction; for bi-directional operation, a double safety relief valve is required. The safety relief valve should not be used as a flow regulator, as this can cause rapid liquid heating.
Important Technical Specifications
The pump's type designation, found on the nameplate, encodes its properties, including pump family name (TG = TopGear), pump range name (G = General purpose, P = Simplest soft packing version), hydraulics (displacement volume per 100 revolutions in dm³ and nominal port diameter in mm), application (Non-food or FD Food), pump material (G = cast iron), and port connection type (Thread connections, PN16 flanges to DIN2533, or PN20 flanges to ANSI 150 lbs).
Key characteristics include:
- Maximum Temperature: Overall temperature of TopGear GP pumps is 300°C, though GP2-25, GP3-32, and GP6-40 sizes are limited to 200°C due to ball bearing type 2RS. Minimum temperature is -20°C. Temperature limits also depend on bearing bush and shaft sealing materials.
- Maximum Differential Pressure: 16 bar.
- Hydrostatic Test Pressure: 24 bar (1.5 times the differential pressure).
- Maximum Viscosity: For packed gland (PO) shaft sealing, maximum viscosity is 80,000 mPa.s.
- Shaft Sealing: Available options include packed gland (no lantern ring) with various packing ring materials:
- TC (PTFE graphite): -200°C to +280°C, pH 0-14.
- AW (Aramide - white): -50°C to +250°C, pH 1-13.
- CC (Graphite fibre): -60°C to +500°C, pH 0-14.
- Safety Relief Valve: Available in various sizes (18, 27, 35, 50, 60 mm inlet diameter) and materials (cast iron). Working pressure classes range from 1-4 bar to 9-16 bar. Standard set pressure is 1 bar above the indicated maximum working pressure.
- Internal Materials: Bush materials include hardened steel, carbon, ceramic, hard metal, and bronze. Rotor and shaft materials include iron with hardened, nitrided stainless, or hard-coated stainless steel; nitrided nodular iron with hardened, nitrided stainless, or hard-coated stainless steel; and stainless steel with hardened, nitrided stainless, or hard-coated stainless steel.
- Maximum Torque: Nominal torque (Mn) and starting torque (Md) vary by pump size and rotor/shaft material combination, with Md being higher for start-up.
- Mass Moment of Inertia: Varies by pump size, from 0.25 x 10⁻³ kgm² for TG GP2-25 to 570 x 10⁻³ kgm² for TG GP360-150.
- Axial and Radial Clearances: Minimum and maximum axial clearances vary by pump size. Diametral clearances on the pin/idler bearing also vary. Extra clearance classes (C0, C1, C2, C3) can be specified.
- Play between Gear Teeth: Minimum and maximum play between gear teeth vary by pump size.
- Maximum Solid Particle Size: Varies by pump size, from 80 µm for TG GP2-25 to 225 µm for TG GP360-150.
- Radial Load on Shaft End (Fr): Maximum allowable radial force on the shaft end ranges from 400 N for TG GP2-25/3-32 to 6000 N for TG GP360-150.
- Sound Level: TopGear pumps produce noise due to contact between internal parts and pressure variations. Sound pressure levels (LPA) without drive range from 51 dB(A) to 72 dB(A) at 25% nmax, and up to 92 dB(A) at 100% nmax, depending on pump size. Ear protection may be required if operating area sound levels exceed 85 dB(A).
Usage Features
- Installation: Pumps should be located as close as possible to the liquid source, preferably below the liquid supply level, for optimal suction conditions. Adequate room for inspection and maintenance is required. Outdoor installations are possible, but a roof is advised in very wet conditions.
- Piping: Use piping with a diameter equal to or larger than the connection ports, and keep lines as short as possible to minimize pressure losses. Strainers are essential to prevent foreign particles from damaging the pump.
- Drives: If a bare shaft pump is supplied, the user is responsible for the drive and guarding of moving parts. Motors should have a starting torque at least 25% higher than the pump's power consumption. Shaft alignment between pump and motor is critical and must be checked and re-aligned if necessary after transport and mounting.
- Electrical Heating: Available on the pump cover (in the idler pin) and/or intermediate casing, designed for temperatures up to 250°C. Users are responsible for connecting cartridge heaters to the electric supply (110V or 230V) and ensuring proper temperature control to prevent motor start-up before the required temperature is reached.
- Start-up: Before commissioning, ensure the pump is filled with liquid, sufficiently preheated (if applicable), and suction/discharge valves are fully open. Check motor rotation direction, suction pressure, RPM, and for leaks.
- Shut-down: Turn off the motor, close auxiliary service lines, and clean the pump if the liquid solidifies to prevent blockages.
Maintenance Features
- General Maintenance: Regular maintenance is crucial to prevent malfunctions. Operations should be performed by qualified personnel wearing appropriate safety clothing.
- Conservation: For longer storage periods, drain the pump, treat internal parts with VG46 mineral oil (or food-grade oil for food applications), and turn the shaft a full turn once a week to ensure proper oil distribution.
- Cleaning: The pump should be cleaned thoroughly, especially for food applications, to remove residual mineral oil. Suction lines must also be cleaned.
- Draining: Before maintenance, depressurize the pump and allow it to cool. For solidifying fluids, drain immediately after shutting down. Open venting plugs and drain plugs. Purge pump spaces with flush media if necessary.
- Electrical Installation Maintenance: Only trained and qualified personnel should perform electrical maintenance after disconnecting power.
- Nuts and Bolts: Replace damaged nuts and bolts. Use a torque wrench for tightening, referring to specified torque values.
- Plastic/Rubber Components: Replace components showing signs of expansion, shrinkage, hardening, or other damage.
- Flat Gaskets: Always replace flat gaskets and elastic rings with genuine spares after disassembly.
- Filter/Strainer: Regularly clean filters or suction strainers to prevent clogging and pressure losses.
- Anti-friction Bearings: TG GP2-25, GP3-32, and GP6-40 pumps have sealed, greased-for-life ball bearings. Larger pumps (TG GP15-50 and up) require relubrication every 5000 running hours or 12 months, whichever comes first. Do not overfill or mix different grease grades.
- Sleeve Bearings: Regularly check for wear on gear wheels and sleeve bearings. Replacement of sleeve bearings requires contacting the local supplier.
- Shaft Seal (Gland Packing PO): Regularly check for leaks. If excessive, replace packing rings using a packing extractor. Ensure proper assembly and run-in of new packing rings, allowing slight leakage for lubrication.
- Clearance Adjustment: Axial clearance can be adjusted to compensate for wear, reduce slip for low-viscosity liquids, or reduce friction for highly viscous liquids.
- Troubleshooting: A comprehensive troubleshooting guide is provided to address common issues such as no flow, pump stalls, abnormal noise, rapid wear, pump consuming too much power, motor overloading, and pump leaks, with corresponding remedies.
- Disposal: Pumps should be completely drained and cleaned before disposal, following local regulations. Disassemble and recycle parts where applicable.
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