Flowserve Durco Guardian ASME B73.3 Magnetic Drive Pump

Flowserve Durco Guardian ASME (ANSI) magnetic drive pump

The Flowserve Durco Guardian is a horizontal magnetic drive pump built for emission-free services. It follows ASME (ANSI) B73.1-2001 dimensional standards, the ASME B73.3-2003 sealless pump standard and HI 5.1-5.6 (1992), and it is offered in 18 sizes. The wet end is the same casing and reverse vane impeller as the Durco Mark 3 ASME pump, so a plant can convert a sealed Mark 3 to a sealless Guardian without redesigning the hydraulics. Seven Star LLC supplies the Guardian in Oman and the GCC as an independent supplier in Muscat.

A magnetic drive pump replaces the mechanical seal with a containment shell and a set of coupled magnets, so there is no shaft seal to leak. The Guardian uses this principle for acids, solvents, toxic and flammable liquids and other duties where release to the atmosphere cannot be accepted.

Guardian material codes and configurations

Titanium and Hastelloy B-2 can be supplied for special applications. Configuration options include close-coupled, self-priming and labyrinth oil seals, with standard or contained back pullout.

Guardian technical specifications

How the Guardian cools and lubricates itself

High-pressure process fluid enters the silicon carbide bushings and journals through injection ports near the impeller discharge. Spiral and radial grooves spread the fluid for lubrication, pressure then pushes it through the gap between inner magnet and containment shell, where it removes the heat generated by eddy currents, and finally it returns to the low-pressure region behind the impeller through return ports. Taking the coolest possible fluid to the bearings is what permits operation to 290 °C. The stationary silicon carbide bushings are cartridge mounted with tolerance rings that compensate for thermal expansion, and the cartridges are assembled at the factory.

An external flush plan can be added, introducing a clean, compatible flush liquid or a filtered bypass flush into the containment shell area to widen the application range, for example with liquids containing fine solids or with a narrow temperature margin to vapour pressure.

Where the Guardian fits among Flowserve pumps

The brochure lists complementary designs: Mark 3 ASME and ISO chemical process pumps, the CPXS ISO magnetic drive pump, the PVML-Mag vertical in-line API pump, the PolyChem M-Series non-metallic magnetic drive pump and the ERPN-Mag. The Mark 3 ISO and the HPX-Mag pages on this site cover close relatives. Choose the Guardian for metallic chemical duty up to 24 bar, and the HPX-Mag for API 685 service with secondary containment and higher flows.

Because the pump has no seal flush by default, its reliability rests on the internal lubrication path, which is why the shell, bushings and journals are the parts to inspect at each overhaul. Keep a spare rotor kit and a set of bushings for critical services, and record bushing wear at each opening so replacement can be planned before a failure.

Selection and ordering checklist for the Guardian

• Fluid composition, temperature, vapour pressure, viscosity and solids content.
• Flow, head and NPSH available, with the pump size selected from the range chart.
• Alloy code D4, D20 or DC3, or special materials.
• Back pullout type: standard or contained.
• Whether an external flush is needed, and instrumentation to protect against dry running and loss of flow.
• Close-coupled or frame-mounted, self-priming need and driver power.
• Ex-area classification of motor and instruments.

Installation, commissioning and maintenance

Standard back pullout allows general inspection with the casing and piping in place, while contained back pullout keeps the process fluid confined during drive-end maintenance, so no draining or purging is needed and maintenance personnel are not exposed. Jackbolts add safety and ease assembly. Precise running clearances protect the containment shell. Commissioning must avoid dry running; a power monitor or flow switch is a good practice since silicon carbide bushings depend on the process fluid.

Typical applications of the Guardian in Oman and the GCC

Flowserve lists acid transfer, chlor-alkali, corrosive services, difficult-to-seal, flammable, toxic and valuable liquids, organic chemicals, polymers, solvents, ultrapure liquids and water treatment. In Oman and the GCC those translate into chemical injection and transfer at refineries and petrochemical units, chlor-alkali and desalination chemical dosing, and laboratory or specialty chemical plants where releases need to be zero.

Information to send with your Guardian RFQ

• Liquid, temperature and vapour pressure.
• Flow and head, and suction conditions.
• Material code and any flush plan requirement.
• Instrumentation and area classification.
• Driver data and site frequency.
• Delivery location.

Site conditions in Oman for the Guardian

Pump selection in Oman has to account for the site, not only the duty point. Process liquids and cooling water can arrive warm in summer, which raises vapour pressure and reduces the available NPSH, so check the NPSH margin of the Guardian at the highest expected liquid temperature. Motors on outdoor skids also work in high ambient air, and their rating, enclosure and cooling should match that environment.

For hygienic and process plants in the Gulf, plan the spare parts that wear first, such as seals, O-rings and bearings, and keep the material certificates with the plant records. Sharing the fluid, temperature, flow, head and cleaning regime with the supplier at RFQ stage makes it easier to confirm that the Guardian is the right configuration before the order is placed.

Documents and quotation

The Flowserve Durco Guardian brochure is attached on this page. Send your duty data and we will confirm availability and lead time. Seven Star LLC is an independent supplier and does not claim any official status with the manufacturer.