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

The built-in safety relief valve protects against overpressure. Set the cracking pressure to 1.05-1.15 times the rated working pressure. To adjust, depressurize first, loosen the locking nut, rotate the spring preload until target pressure is reached, then retighten. Never adjust while running.

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

When handling high-viscosity fluids like paints or glazes, operating frequency must be reduced. Increased viscosity reduces suction lift and increases diaphragm load. Reduce frequency by 10-15% for every 50% increase in viscosity. Reserve 10-15% power margin to prevent motor overload.

How to troubleshoot shaft seal leakage on QBY pump?

The medium side of a QBY pump has no dynamic seals; focus inspection on the air-side packing gland. If dripping occurs, check for pressure fluctuations. Minor leaks can be fixed by tightening the packing gland 2-3 turns. If ineffective or worn, replace the packing rings. Regularly clean air valves to prevent debris jamming.

QBY SERIES8 modelsHS: 8413.50.90

QBY Pneumatic Double Diaphragm Pump (QBY Series)

Chemical, Magnetic & Diaphragm Pumps•QBY

Flow Range: 0.8 ~ 40 m³/h
Pressure Range: 0.7 ~ 0.7 MPa
Model: QBY-10 → QBY-100
Customs HS Code: 8413.50.90

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

QBY Pneumatic Double Diaphragm Pump (QBY Series)

Hydraulic Principle & Internal Construction

The QBY series air-operated double diaphragm (AODD) pump is powered by compressed air (0.2–0.8 MPa), providing 100% stall-free and explosion-proof operation in hazardous Class 1 Division 1 zones. Inherently self-priming up to 7 m, submersible, and dry-run capable, it transfers abrasive slurries, high-viscosity paints, glues, and shear-sensitive fluids without motor thermal hazard.

Model-by-Model Technical Specifications

Model	Inlet	Outlet	Flow (m³/h)	Pressure (MPa)
QBY-10	DN10	DN10	0.8	0.7
QBY-15	DN15	DN15	1	0.7
QBY-25	DN25	DN25	2.4	0.7
QBY-40	DN40	DN40	8	0.7
QBY-50	DN50	DN50	16	0.7
QBY-65	DN65	DN65	28	0.7
QBY-80	DN80	DN80	40	0.7
QBY-100	DN100	DN100	40	0.7

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 QBY series 1-page technical datasheet covering all 8 model configurations.

Media Compatibility & Viscosity / Temperature Guide

Medium	Max Viscosity (cSt)	Application Note
Industrial Paints / Concentrated Acids & Alkalis	20,000	PTFE Diaphragm
Ceramic Glaze Slurry / Mining Drilling Mud	50,000	Suspended Solids ≤10mm Permissible
Volatile Solvents / Used Motor Engine Oil	1,000	ATEX / Explosion-Proof Certified
Electronic Encapsulation Adhesives & Sealants	30,000	Explosion-Proof Paint Spraying Duty

International Benchmark & Interchange Guide

International Benchmarks

Wilden (USA) AODD pumps
Graco / Sandpiper / ARO / Yamada AODD pumps

Interchange Note

Air-operated double diaphragm (AODD) pump. 100% interchangeable in porting and performance with Wilden Original series, Aro EXP, and Sandpiper metallic/plastic AODD pumps.

Materials & Shaft Seal Selection Guide

Engineering metallurgy and seal selection advice for corrosiveness and temperature: For strong acids, alkalis, or high temperatures, prefer 316L stainless steel or PTFE-lined bodies over gray cast iron to prevent corrosion. For packing seals, recommend PTFE braided packing with graphite backing up to 200°C. If the medium contains solids, use a lubricated mechanical seal scheme to ensure long-term leak-free operation.

Casing & Housing Materials: Cast IronAluminum Alloy304 / 316 Stainless SteelPolypropylene (PP)PVDF Fluoropolymer
Rotor / Gear / Screw Elements: Sealless Design (Air-Operated Diaphragm Driven)
Diaphragm Materials: PTFE (Teflon) DiaphragmSantoprene (TPV) DiaphragmFKM (Viton) Fluoroelastomer Diaphragm
Shaft Sealing Options: Integrated PTFE/Rubber Sealless Static Diaphragm Barrier

Engineering FAQ

Although QBY pumps are positive displacement, proper suction design is critical for high-viscosity or gaseous fluids. Pipe diameter should match or exceed the inlet port size to minimize velocity. Maintain at least 3 pipe diameters of straight run before the inlet to eliminate turbulence. Ensure NPSHa exceeds 0.5 meters to prevent cavitation and flow pulsation.

📐 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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