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

The G Single-Screw Pump is equipped with an internal safety relief valve to protect the elastomer stator. Set the cracking pressure to 1.05 to 1.15 times the rated operating pressure. To adjust, loosen the locking nut and use a specialized tool to modify the spring preload until the target opening pressure is reached, then retighten securely. For systems requiring frequent over-pressure operation, install an external bypass valve instead of relying solely on the internal relief valve to extend stator life.

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

When handling fluids with significantly increased viscosity, the pump operating speed must be reduced. High viscosity causes excessive heat generation in the rotor-stator friction pair and increases suction resistance. A rule of thumb is to reduce speed by approximately 20% to 30% for every doubling of viscosity to prevent cavitation and dry running. Variable Frequency Drive (VFD) control is the optimal method to dynamically adjust frequency based on real-time viscosity changes, ensuring the motor does not overload and fluid transfer remains smooth.

How to troubleshoot shaft seal leakage on G pump?

When troubleshooting shaft seal leakage on the G pump, first check the packing gland tightness; slight dripping is normal for lubrication, but excessive leakage requires readjustment or replacement. For mechanical seals, ensure the flushing scheme (e.g., Plan 53) is clear to prevent particle blockage. Routine maintenance includes regularly greasing the bearing cavity and inspecting stator rubber wear. If abnormal vibration or noise occurs, stop immediately to avoid damage from hard contact under high-speed rotation.

G SERIES9 modelsHS: 8413.60.31

G Single-Screw Progressive Cavity Pump (G Series)

Industrial Screw Pumps•G

Flow Range: 0.8 ~ 150 m³/h
Pressure Range: 0.6 ~ 2.4 MPa
Motor Power: 0.75 ~ 75 kW
Model: G20-1 → G85-1
Customs HS Code: 8413.60.31

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

G Single-Screw Progressive Cavity Pump (G Series)

Hydraulic Principle & Internal Construction

The G series progressive cavity pump (single screw pump) consists of a high-precision metal eccentric screw rotor rotating inside an elastomeric stator. The sealed cavities travel progressively from suction to discharge, handling abrasive slurries, high-viscosity sludge, dewatered filter cakes, and shear-sensitive media with high suction lift capability.

Model-by-Model Technical Specifications

Model	Inlet	Outlet	Flow (m³/h)	Pressure (MPa)	Speed (rpm)	Motor (kW)
G20-1	DN32	DN32	0.8	0.6	400	0.75
G25-1	DN40	DN40	2	0.6	420	1.5
G30-1	DN50	DN50	5	0.6	450	2.2
G35-1	DN50	DN50	8	1.2	480	4
G40-1	DN65	DN65	12	1.2	500	5.5
G50-1	DN80	DN80	20	1.2	520	7.5
G60-1	DN100	DN100	40	1.8	540	15
G70-1	DN125	DN125	80	2.4	560	37
G85-1	DN150	DN150	150	2.4	580	75

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 G series 1-page technical datasheet covering all 9 model configurations.

Media Compatibility & Viscosity / Temperature Guide

Medium	Max Viscosity (cSt)	Application Note
Dewatered Sewage Sludge Cake / Thickened Slurry	1,000,000	Solid Content ≤40%
Paper Coating Color / Kaolin Pigment Slurry	500,000	Textile Dyeing & Printing Paste Transfer
Distillers Grains / Brewery Spent Mash	300,000	Food & Beverage Processing
Limestone-Gypsum Flue Gas Desulfurization (FGD) Slurry	200,000	Environmental Engineering
Construction Grout / Cement Mortar Slurry	400,000	Handles Entrained Particles

International Benchmark & Interchange Guide

International Benchmarks

NOV Mono (France/UK) progressive cavity pumps
Seepex / Netzsch progressive cavity pumps

Interchange Note

Single-screw progressive cavity pump. Interchangeable with Seepex (MD/BN series), Netzsch (NM series), and NOV Mono (C range) stator/rotor geometries.

Materials & Shaft Seal Selection Guide

For G Single-Screw Pump material and seal selection, match components to fluid characteristics. Cast iron or ductile iron parts suit general slurries; use 304 or 316L stainless steel for corrosive media like desulfurization slurry. For seals, packing glands are simple but require maintenance, suitable for high-solid content fluids; mechanical seals offer longer life and lower leakage but require clean flushing fluid. For high-temperature or high-viscosity applications, select NBR or FKM elastomers for stators to ensure long-term stability.

Casing & Housing Materials: HT200 Cast Iron304 / 316 Stainless Steel
Rotor / Gear / Screw Elements: 304 / 316 Hard-Chrome Plated Rotors40Cr Tool Steel Rotor
Stator Materials: NBR (Nitrile Butadiene Rubber) StatorFKM (Viton) Fluoroelastomer StatorEPDM Rubber Stator
Shaft Sealing Options: Slurry & Particle Resistant Tungsten/SiC Mechanical SealOil-Impregnated PTFE Braided Packing

Engineering FAQ

To prevent cavitation on the G Single-Screw Pump, maximize suction pipe diameter (preferably equal to or larger than discharge) to minimize flow velocity and friction losses. Install at least 5 pipe diameters of straight run before the inlet to stabilize the flow profile. Avoid elbows or valves near the suction flange. Ensure the Available NPSH (NPSHa) exceeds the Required NPSH (NPSHr) by a minimum safety margin of 0.5 meters, which is critical when handling solids-laden slurries.

📐 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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