Is / ISR Type Centrifugal Pump

The Is/ISR type centrifugal pump adopts a single-stage single-suction, cantilevered, horizontally axially suction, radially discharging structure. The entire series consists of 34 basic types and 242 specifications, and is the most widely used general centrifugal pump platform in the industrial and civil water supply and drainage fields. IS and ISR share the same set of installation dimensions and interface standards - the IS type is used to convey clear water or liquids with physical and chemical properties similar to water, with a medium temperature of ≤ 80℃; the ISR type is a hot water circulation pump version based on the IS type, with a medium temperature of up to 130℃ (for some specifications, the design upper limit is 150℃), specifically used for boiler feed water, urban heating circulation, and waste heat utilization, etc. The greatest engineering value of both lies in "interchangeability" - the same pump position can be installed as IS to convey clear water today, and tomorrow it can be replaced with ISR to convey hot water, and the pipeline and motor base remain completely unchanged.

The Is type pump is designed according to the performance and dimensions specified in ISO 2858. Apart from the pump body, other components such as the pump cover, impeller, shaft, sealing ring, shaft sleeve, suspension body, rolling bearing, etc. constitute the rotor components. The rotor parts of the pump are connected to the pump body by bolts. During major repairs, the parts can be removed. There is no need to move the pump body as well as the inlet and outlet pipes. The pump casing (i.e. the pump body and pump cover) constitutes the working chamber of the pump. To balance the axial force of the pump, most pumps have sealing rings on both the front and rear of the impeller, and a balance hole is set on the rear cover plate of the impeller. Due to the relatively small axial force of some pumps, there are no sealing rings and balance holes on the rear side of the impeller, and the axial force is borne by the rolling bearings.

Back Door Extraction Structure: The pump body and pump cover are separated from the back side of the impeller. During maintenance, there is no need to disassemble the pump body, suction pipeline, drainage pipeline, or motor. Just remove the middle section of the coupling, and the rotor components can be fully withdrawn for maintenance. This is the most popular design feature of the IS/ISR series among maintenance engineers.
Cantilevered Rotor: The impeller is mounted on a thickened shaft, and the radial load is borne by a heavy-duty bearing assembly. It operates smoothly with minimal vibration.
Two-choice Mechanical Seal:
Soft Packing Seal: Low cost and simple maintenance. Equipped with packing ring and external flushing water. Suitable for clear water and conditions with a temperature ≤ 80℃.
Mechanical Seal: Extremely low leakage. The ISR hot water type is standardly equipped with an axial seal cooling water jacket (introducing normal temperature clear water for cooling), allowing the medium temperature to reach 130℃.
Bearing Lubrication: Single row radial ball bearing, lubricated with thin oil. The bearing body has an oil level sight glass, making maintenance convenient.

The "ISR" type centrifugal pump, with its characteristics of "standard, reliable, easy to maintain, and highly interchangeable", is the preferred general pump in the following fields:
Industrial water supply and drainage: water supply for factory production and daily life, process cooling water circulation, workshop drainage
Boiler matching: ISR type is specifically used for hot water boiler water supply, boiler circulating water, and heat station circulating pumps
Urban heating: ISR type is used for urban centralized heating pipe circulation, heat exchange station primary/secondary water circulation
Agricultural irrigation and drainage: field irrigation, flood discharge pumping stations, sprinkler systems, channel water lifting
Municipal engineering: water supply pumps for waterworks, reverse flushing pumps for sewage plants, municipal pipe network boosting
Fire protection system: indoor and outdoor fire hydrant pumps, sprinkler pumps, water curtain pumps
Energy and metallurgy: circulating water in power plants, cooling water in steel mills, underground drainage in mines

Material selection path:
Normal temperature water → HT200/HT250 cast iron (standard configuration)
High-temperature water (ISR type) → HT250 + mechanical seal + shaft seal cooling water jacket
Micro-corrosive medium → QT600 ductile iron or SS304 stainless steel
Weak acid and alkali medium → SS316/SS316L stainless steel
Shaft seal selection:
Water type IS → Packing seal (economical) or mechanical seal (zero leakage)
Hot water type ISR → Mechanical seal + shaft seal cooling water jacket (essential)
Drive method: Standard motor direct connection (elastic coupling); optional belt drive, variable frequency speed regulation
Custom service: Special flanges (ANSI/DIN/GB), explosion-proof motor, outdoor protective cover, custom paint color, OEM nameplate, complete skid-mounted unit (pump + motor + base + valve + instrument)

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Q4: How to choose between packing seal and mechanical seal?
A: IS type: for clean water conditions, budget-sensitive, with sufficient maintenance staff → choose packing seal (allowing a small amount of dripping water 20–60 drops/minute, regular tightening required); requires zero leakage, high automation → choose mechanical seal. ISR hot water type: must select mechanical seal + shaft seal cooling water jacket, because packing seal cannot withstand the erosion of 130℃ hot medium, mechanical seal can work stably under the protection of the cooling water jacket.
Q5: What to do if the pump's performance is insufficient? Can it be speed-adjusted?
A: There are three methods: ① Blade cutting - by cutting the outer diameter of the blade (A/B/C three-speed cutting) to reduce flow and head, suitable for conditions below the design point; ② Variable speed operation - using frequency conversion speed regulation or belt wheel speed adjustment to change the speed to regulate flow and head, with significant energy-saving effect; ③ Upgrade - if the conditions exceed the current model range, you can upgrade to the adjacent specification. For IS/ISR series, there are 34 basic types, covering a dense range, and usually a more suitable model can be found.
Q6: Warranty and spare parts supply?
A: Whole machine warranty for 12 months (except for wear parts such as mechanical seal, packing, bearing, sealing ring, shaft sleeve). It is recommended to be equipped with: 1 set of mechanical seal, 1 set of bearing, 1 piece of sealing ring, 1 piece of shaft sleeve when the first purchase is made. As the most common pump type, IS/ISR is produced by various pump factories of all sizes across the country, and spare parts supply is extremely abundant. For regular specifications, they can be shipped within 3–7 days. We provide complete spare parts for all 34 basic types, including the impeller, pump body, pump cover, suspension, shaft, and all components.

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