How to calibrate and adjust the safety relief valve on 3G pump?

The safety relief valve at the discharge should be calibrated to open between 1.05 and 1.15 times the normal operating pressure. Upon detecting overpressure, the valve diverts fluid back to the suction side to protect the pump body and drive motor from mechanical overload. Regularly verify spring preload settings to ensure accurate cracking pressure and prevent malfunction.

What are the speed reduction rules for 3G pump when handling high viscosity fluids?

As fluid viscosity increases, pump operating speed must be reduced. High-viscosity fluids generate significant shear heat and friction resistance within screw clearances. Maintaining rated speed causes excessive suction vacuum leading to cavitation/air binding and potential motor burnout. Typically, speed should be reduced to the 60%-80% range of rated RPM based on viscosity curves.

How to troubleshoot shaft seal leakage on 3G pump?

For packing seals, slight dripping is acceptable for lubrication and cooling but should not be a jet; tighten gland evenly in a diagonal pattern. For mechanical seals, ensure flushing schemes (e.g., Plan 53) are correctly implemented. Regularly inspect oil level and temperature in the bearing cavity; stop immediately if abnormal leakage or temperature rise occurs to check bushing wear.

3G SERIES10 modelsHS: 8413.60.31

3G Triple Screw Pump (3G Series)

Industrial Screw Pumps•3G

Flow Range: 0.6 ~ 300 m³/h
Pressure Range: 0.6 ~ 4 MPa
Motor Power: 0.75 ~ 160 kW
Model: 3G 20×4 → 3G 100×2
Customs HS Code: 8413.60.31

WhatsApp Quick Quote Email for Price & DrawingModel-by-Model Technical Specifications ↓

Hydraulic Principle & Internal Construction

The 3G series triple screw pump operates by the synchronized meshing of one central driving screw and two driven idle screws within a close-tolerance liner. Fluid is trapped in sealed axial cavities that continuously move along the screws without pulsation, churning, or emulsification. Compliant with GB/T 10886 and ISO standards, it is the worldwide benchmark for turbine lube oil, boiler fuel pressurization, and marine hydraulics.

Model-by-Model Technical Specifications

Model	Inlet	Outlet	Flow (m³/h)	Pressure (MPa)	Speed (rpm)	Motor (kW)
3G 20×4	DN25	DN25	0.6	0.6	2900	0.75
3G 25×4	DN32	DN32	1.5	1	2900	1.5
3G 30×4	DN40	DN40	3	1.6	2900	3
3G 36×4	DN50	DN50	6	2.5	2900	5.5
3G 42×4	DN50	DN50	12	3	2900	11
3G 50×3	DN65	DN65	20	3	2900	18.5
3G 60×2	DN80	DN80	40	2.5	1450	30
3G 70×2	DN100	DN100	80	2.5	1450	55
3G 80×2	DN125	DN125	160	3	1450	110
3G 100×2	DN200	DN200	300	4	1450	160

Selection guidance: match your duty point to the closest model below, then confirm with our engineers. Values are rated operating points at the listed speed.

Need Complete Engineering Dimensions & Curves?

Download the official 3G series 1-page technical datasheet covering all 10 model configurations.

Media Compatibility & Viscosity / Temperature Guide

Medium	Max Viscosity (cSt)	Application Note
Heavy Fuel Oil / Marine Bunker Fuel	760	Speed regulated up to 3,000 cSt
Steam Turbine & Gearbox Lube Oils	320	Pressurized Forced Lubrication Systems
Transformer Insulating Oil	200	Continuous Recirculation Duty
Hydraulic Fluid / Mineral Hydraulic Oil	400	High-Pressure Main Feed Pump

International Benchmark & Interchange Guide

International Benchmarks

IMO (Sweden) three-screw pump series
Allweiler / Leistritz three-screw pumps

Interchange Note

Triple screw pump built to GB/T 10886 standard. 100% interchangeable with IMO (Sweden) ACE, ACG, and ACF series, as well as Allweiler SN and Leistritz three-screw pumps.

Materials & Shaft Seal Selection Guide

Engineering metallurgy and seal selection advice for corrosiveness and temperature: For heavy oil or fuel containing impurities, use high-phosphorus cast iron or tin bronze for bushings due to superior wear resistance. Use HT250 gray iron or QT400-18 ductile iron for casings to enhance impact resistance. If the medium is corrosive (e.g., seawater cooling), select 316L stainless steel with double mechanical seals. Packing glands are suitable for general conditions, while mechanical seals require flushing liquid to prevent dry friction and overheating failure.

Casing & Housing Materials: HT250 Gray Cast Iron (GG25)Ductile Iron (GGG40 / QT450)ZG230 Cast Carbon Steel
Rotor / Gear / Screw Elements: 38CrMoAlA Nitrided Alloy Steel ScrewsCarburized & Quenched Alloy Steel Screws
Liner & Sleeve Materials: Wear-Resistant Tin-Bronze BushingHigh-Phosphorus Cast Iron Liner Bushing
Shaft Sealing Options: High-Precision Silicon Carbide (SiC) Mechanical SealOil-Resistant Elastomeric Lip Seal

Engineering FAQ

Ensure suction pipe diameter matches or exceeds the pump inlet flange size to minimize flow velocity and pressure drop. Maintain at least 5 pipe diameters of straight run before the inlet to avoid turbulence from elbows or valves. Strictly calculate Net Positive Suction Head Available (NPSHa) to ensure it exceeds NPSHr by a minimum margin of 0.5 meters, preventing air ingestion and cavitation damage.

📐 Engineering Selection Methodology

Correct pump selection starts from the fluid, not the pump. Confirm the medium name and actual viscosity at working temperature, the required flow and differential pressure or head, suction conditions (flooded or lift), and whether the fluid crystallizes, shears, contains particles or gas. Positive displacement pumps must always be protected by a relief valve or pressure bypass on the discharge line, and must never be started against a closed valve unless a bypass is fitted. For viscous duties, derate rotational speed to preserve volumetric efficiency; for crystallizing or high-freezing-point media, specify jacketed casings with steam or thermal-oil heating. Our engineers verify each enquiry against these rules before quoting.

🏭 Manufacturing & Quality Control

Castings are produced in our own foundry cluster with material certificates for each heat number. Gear profiles, screw threads and rotor lobes are hobbed, ground and wire-cut to tolerance, then assembled with matched bearing sets. Before dispatch every pump passes casing hydrostatic pressure testing, a run-in test at rated speed on an oil bench, and relief valve cracking-pressure verification; test records are archived against the pump serial number and can be supplied with the shipment.

📦 Export Packaging & Delivery

Pumps are preserved with anti-rust coating, flanges blanked, and packed in export-grade plywood cases with steel strapping for sea freight. Document packs include operating manual, performance test record, packing list and material certificates on request. Standard models ship from stock; engineered configurations typically require 15-35 days depending on casing material and seal options. Spare rotor sets, seal kits and relief valve assemblies can be quoted together with the base pump.

Typical Applications & Industry Use Cases

The media compatibility table above maps directly to real industry duties. In lubrication circuits, size the pump for continuous duty at 70-80% of rated flow to leave margin for viscosity drift as oil warms up. In chemical transfer, confirm the medium's specific gravity and whether it is shear-sensitive before fixing rotational speed. In food and sanitary service, schedule CIP cycles around the product changeover plan and verify elastomer compliance with the relevant food-contact regulation in your market. In hot oil and asphalt service, always pre-heat the casing to the medium temperature before start-up so internal clearances are at operating dimension - a cold start against solidified product is the single most common cause of gear pump failures reported from the field.

Commissioning & Maintenance Guidance

Before first start: verify rotation direction, fill the casing with medium, open the discharge bypass, and jog the motor to confirm free rotation. Check the relief valve setting against the system design pressure and lock the adjuster. During the first hour, record suction and discharge pressures, medium temperature, and motor current - deviations from the quotation duty point usually indicate suction restriction or an over-throttled discharge line. Routine maintenance intervals: inspect the shaft seal weekly during the first month, then monthly; check coupling alignment after any pipe work; drain and inspect the bearing housing annually. Keep a log of running hours so rotors, bearings and seals can be replaced on condition rather than after failure.

Troubleshooting Quick Reference

No delivery or loss of prime: check suction line for air ingress, verify foot valve and strainer are submerged and clean, and confirm the casing is primed for pumps without self-priming capability. Flow below nameplate: verify actual rotational speed against the data sheet, confirm medium viscosity is within the rated band, and inspect internal clearances for wear if the pump has long service hours. Abnormal noise or vibration: usually coupling misalignment, cavitation from excessive suction lift, or foreign matter in the pumping chamber. Seal leakage: confirm flush plan and seal face condition; never run a mechanical seal dry. Motor overload: check for over-viscous medium at start-up temperature and confirm the relief valve is not set above the motor's capability. For anything beyond these basics, send us the serial number and symptom - our engineers will respond with a diagnosis.

📋 Standards, Testing & Documentation

Gear pumps in this catalog are designed and acceptance-tested with reference to JB/T 6434 (external gear pumps), three-screw pumps to GB/T 10886, centrifugal chemical pumps to ISO 2858, and sealless or screw pumps to the relevant API 676 guidance, with mechanical seals supplied to API 682 configurations on request. Sanitary models are manufactured with surface finishes suitable for FDA / 3A style hygienic duties. Each shipment can include: performance test record against the quoted duty point, hydrostatic test certificate, material certificates for pressure-retaining parts, operating and maintenance manual, and a dimensional drawing with flange table. Tell us which standards your project specification cites and we will align the documentation pack accordingly.

🔧 Spare Parts & After-Sales Support

Every pump model page doubles as a spare-parts reference: rotor and gear sets, bearing and thrust assemblies, complete seal cartridges, relief valve kits and jacket gasket sets are manufactured in-house to the same drawings as the original build - so spares ordered years later still match. Recommended commissioning spares are one seal set and one gasket set per pump; for critical continuous-duty installations we recommend a full rotor set held on site. When ordering spares, quote the pump serial number and nameplate data so the correct material and clearance class is supplied. Technical support in English is available by email during China business hours, with video call diagnostics available for installation and commissioning issues.

ℹ️ Technical data on this page is sourced from the manufacturer's engineering database and applicable standards (JB/T 6434, GB/T 10886, ISO 2858, API 676). Final selection must be confirmed by our engineers against your actual duty conditions.

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