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

The built-in safety relief valve in the KCB pump cover protects the system from overpressure. The cracking pressure is typically set at 1.05 to 1.15 times the rated working pressure. To adjust, loosen the locking nut and use a specialized tool to rotate the spring preload until the target opening pressure is reached, then retighten and test for proper relief function. Never forcibly disassemble or drastically change factory settings while the pump is running, as this can disrupt gear mesh clearances and increase internal leakage.

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

When handling high-viscosity media such as heavy oils or bitumen, motor speed must be reduced. Since KCB pumps rely on self-lubrication by the medium, maintaining high speeds with viscous fluids causes severe suction resistance leading to cavitation and excessive bearing heat. Engineering practice suggests reducing speed by 10-15% for every doubling of viscosity. Variable Frequency Drive (VFD) control is recommended to automatically adjust frequency based on real-time flow and pressure feedback, preventing motor overload and extending the service life of gears and thrust bushings.

How to troubleshoot shaft seal leakage on KCB pump?

To troubleshoot shaft seal leakage on a KCB pump, first inspect the packing gland tightness. For older packing seals, adjust the locking nuts following the 'little and often' principle to maintain a drip rate of 3-5 drops per minute for lubrication without leakage. If using mechanical seals, verify that the flushing scheme (e.g., Plan 23 or Plan 54) is clear to prevent debris accumulation damaging the sealing faces. In routine maintenance, regularly add oil to the bearing housing to the marked level and listen for operational sounds; stop immediately if abnormal friction noises are detected to check thrust bushing wear.

KCB SERIES9 modelsHS: 8413.60.21

KCB External Spur Gear Oil Pump (KCB Series)

External Gear Pumps•KCB

Flow Range: 1.1 ~ 58 m³/h
Pressure Range: 0.28 ~ 1.45 MPa
Motor Power: 1.5 ~ 15 kW
Model: KCB-18.3 → KCB-960
Customs HS Code: 8413.60.21

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

KCB External Spur Gear Oil Pump (KCB Series)

Hydraulic Principle & Internal Construction

The KCB series external spur gear pump operates via the counter-rotation of two involute spur gears inside a precision-machined casing. As the gear teeth disengage at the suction side, cavity volume expands to generate high suction vacuum. Liquid is carried within the tooth pockets along the casing perimeter and is positively displaced into the discharge port as the teeth mesh. Built with high-strength ductile iron or stainless steel gears, nitrided shafts, and an integrated adjustable safety relief valve that prevents overpressure.

Model-by-Model Technical Specifications

Model	Inlet	Outlet	Flow (m³/h)	Pressure (MPa)	Speed (rpm)	Motor (kW)
KCB-18.3	DN25	DN25	1.1	1.45	1400	1.5
KCB-33.3	DN40	DN40	2	1.45	1420	2.2
KCB-55	DN40	DN40	3.3	0.33	1400	1.5
KCB-83.3	DN50	DN50	5	0.33	1420	2.2
KCB-135	DN50	DN50	8	0.33	1440	3
KCB-200	DN70	DN70	12	0.33	1440	4
KCB-300	DN70	DN70	18	0.36	1440	5.5
KCB-483	DN80	DN80	29	0.36	1440	7.5
KCB-960	DN100	DN100	58	0.28	1470	15

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

Media Compatibility & Viscosity / Temperature Guide

Medium	Max Viscosity (cSt)	Application Note
Lubricating Oil / Machine Oil / Hydraulic Oil	1,500	Self-lubricating clean oils without hard particles
Diesel / Kerosene / Light Distillate Oils	500	Ambient to 80°C
Heavy Fuel Oil / Marine Bunker Fuel	1,500	Heating required, temperature ≤250°C
Animal & Vegetable Oils	800	Food Applications Require Stainless Steel

International Benchmark & Interchange Guide

International Benchmarks

IMO AB (Sweden) G/GA external gear series
Allweiler (Germany) AGW external gear pumps
Parker Commercial / Hydac external gear pumps

Interchange Note

Standard external involute gear pump. 100% interchangeable in hydraulic performance with IMO AB (Sweden) G series, Allweiler AGW, and Parker Commercial gear pumps. Standard mounting flange compatible with GB/T and ISO dimensions.

Materials & Shaft Seal Selection Guide

KCB pump casings are typically made of HT250 gray cast iron for ambient non-corrosive media; QT400-18 ductile iron is recommended for higher strength or abrasive applications. Contact surfaces should be 304 stainless steel, upgrading to 316L for highly corrosive environments like acids or alkalis. For sealing, graphite packing rings are recommended for low pressure and small flow rates due to low maintenance costs; mechanical seals are preferred for medium/high pressure or clean media, requiring flushing liquid to prevent dry running. For high-temperature oils, thrust bushings should be made of wear-resistant bronze or self-lubricating composite materials to meet the requirements of forced circulation lubrication, ensuring long-term operational reliability.

Casing & Housing Materials: HT200 Gray Cast Iron (GG20)QT500-7 Ductile Iron (GGG50)AISI 304 Stainless SteelAISI 316L Stainless Steel
Rotor / Gear / Screw Elements: 40Cr Quenched & Tempered Gears42CrMo Nitrided Alloy Steel GearsTin-Bronze Spark-Resistant Alloy Gears
Shaft Sealing Options: PTFE Armored Rotary Shaft Lip SealImpregnated Flexible Graphite PackingSilicon Carbide (SiC) Mechanical Seal

Engineering FAQ

To prevent cavitation in KCB pumps, the suction pipe diameter should match or exceed the rated flow size to maintain fluid velocity below 1.5 m/s. Ensure a straight run of 3-5 pipe diameters before the inlet to stabilize flow patterns and avoid direct alignment with elbows. Installation height must strictly adhere to the allowable suction vacuum limit, accounting for the medium's vapor pressure and temperature, ensuring an NPSHa safety margin of at least 0.5 meters.

📐 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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