Armstrong Fluid Technology — Complete Pumps & Repair Parts · Memphis, TN

Armstrong Fluid Technology —
Hydronic Circulators, Commercial Pumps & Repair Parts

Memphis Control Center stocks Armstrong Fluid Technology complete pumps and repair parts for commercial HVAC and hydronic heating systems — S-25 and S-34 circulators, Series 4030 end suction, Series 4280 close-coupled, and Series 4360/4380 vertical inline complete pumps, plus mechanical seal kits, replacement motors, bearing assemblies, impellers, couplers, gaskets, and flange kits. Founded in Toronto in 1934, Armstrong is an industry leader in commercial hydronic pump systems. Free same-day shipping from Memphis, TN since 1967.

Need a Part? Call Us Call (901) 458-2000
Armstrong Fluid Technology Distributor Complete Pumps & Repair Parts S-25 · 4030 · 4280 · 4360 · 4380 Series Free Same-Day Shipping
Complete PumpsS-25, S-34 circulators and Series 4030, 4280, 4360, 4380 commercial pumps available
Genuine Repair PartsOEM seal kits, motors, bearing assemblies, impellers, couplers, and gaskets
Founded 1934Armstrong Fluid Technology — 90+ years engineering hydronic pump systems from Toronto, Canada
Same-Day ShippingOrders by 2 PM CT ship same day — always free

Note — Armstrong Fluid Technology vs. Armstrong International: This page is for Armstrong Fluid Technology (Toronto, Canada — hydronic circulators, commercial pumps, and pump parts). Armstrong International is a separate company that manufactures steam traps and condensate management equipment. If you're looking for steam traps, see our Temperature Controls category.

Complete Armstrong Pumps

Memphis Control Center carries Armstrong Fluid Technology complete pump assemblies for commercial hydronic systems. Contact our team with your pump model number for parts identification or replacement pump selection.

Hydronic Circulator S-25 Series

Armstrong S-25 Hydronic Circulator Pumps. The S-25 is Armstrong's most common small commercial hydronic circulator for closed hot water heating and chilled water systems. Available in cast iron body (174031MF-013) and bronze/lead-free body (174031MF-043) configurations. 1/12 HP, 115V single phase, 3-piece modular design with radially-split body — allows service without disconnecting pipes. Flanges sold separately. The S-25 uses a 4-spring coupler (806026-001K) between the pump and motor — a routine replacement item during rebuilds. LF (lead-free, NSF/ANSI 61) versions required for potable water applications.

S-25 Series Cast Iron & Bronze Close-Coupled LF Lead-Free Option 174031MF / 174034MF
Commercial Pumps Series 4030 · 4280 · 4360 · 4380

Armstrong Commercial Pump Series for HVAC and Hydronic Systems.

Series 4030 — horizontal end-suction, base-mounted. For commercial HVAC chilled water, hot water, and condenser water systems. Available in a wide range of flow and head capacities.

Series 4280 — horizontal end-suction, close-coupled motor mounted. Compact footprint version of the 4030 without a separate base frame.

Series 4360 — vertical inline centrifugal, close-coupled. Flows to 350 GPM, heads to 200 ft. Available single phase and three phase.

Series 4380 — vertical inline, close-coupled. Similar to 4360. Contact us with your model number for availability.

4030 End Suction Base 4280 Close-Coupled 4360 Vertical Inline 4380 Vertical Inline Up to 350 GPM

Armstrong Pump Repair Parts

Memphis Control Center carries genuine Armstrong Fluid Technology repair parts for Series 4030, 4280, 4360, 4380, S-25, S-34, H-series, and 1050 pumps. Contact us with your pump model and nameplate information for correct part identification — frame size and motor HP determine which seal kit and bearing assembly apply.

Mechanical Seal Kits

8975000-982xx series — OEM mechanical seal kits for 4030, 4280, 4360, 4380 series pumps. Available in standard (Buna), Viton (hi-temp), EPDM, and glycol service configurations. Frame size (143–215 or 254–326) determines the correct kit. The 8975000-962 is the large comprehensive seal kit.

Replacement Motors

OEM Armstrong replacement motors for S-series and commercial pump series. The 811757-001 is the 1/2 HP, 115/208-230V single phase motor for Armstrong pump assemblies. Contact us with your motor nameplate data for the correct replacement.

Bearing Assemblies

Multiple bearing assemblies available depending on pump model. 818504-000K (SBA-MF) fits Series S-55, S-57, H-51, H-52, H-53, H-54, and 1050 series — replaces obsolete 816032MF-000. For S-25 rebuilds use 818254-003K. For S-35/H-32 use 818324-003K. For H-41/S-45/S-46 use 818404-000K. Call us with your pump model for the correct assembly.

Couplers

806026-001K — 1/2" x 1/2" 4-spring cast iron coupler for S-25, S-34, S-35, H-32, and H-41 pumps. Connects the impeller shaft to the motor shaft. Routine replacement item during pump rebuilds. Note: S-45, S-46 use the 806168-001 coupler instead.

Impellers

Bronze and Noryl impellers for Armstrong S-series, H-series, and commercial pump series. Impeller selection depends on pump model and trim size. Contact us with your pump model and existing impeller part number for correct identification.

Gaskets, Flanges & Accessories

Casing gaskets, flange kits (cast iron and bronze, LF lead-free), shaft sleeves, water slingers, cap screws, and O-rings for Armstrong pump series. The 816013-841 is the 3/4" bronze lead-free flange kit. 816013-211K is the 3/4" cast iron flange set.

Commonly Ordered Armstrong Parts

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174031MF-043S25AB 1/12HP 115V Bronze Circulator 174031MF-013S25AB 1/12HP 115V Cast Iron Circulator 174034MF-043S-34 Bronze Body Circulator 174036MF-113S-Series Larger Circulator 811757-0011/2 HP Motor 115/208-230V Single Phase 806026-001KCoupler 4-Spring S-25/S-34/S-35/H-32/H-41 8975000-962Mechanical Seal Kit — Large 818504-000KBearing Assembly MF — S/H/1050 Series 810150-251Shaft Sleeve New Style Without Spacer 816013-8413/4" Bronze Flange Kit LF Lead-Free 816013-211K3/4" Cast Iron Flange Set & Hardware 816301-025Impeller Assembly Steel H41 D251929-001Casing Gasket 406622-000Water Slinger 805316-010Armstrong Pump Part All Armstrong PartsBrowse all 944 Armstrong products
Armstrong Fluid Technology

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Need help identifying an Armstrong part?

Give us your pump model number and nameplate data — we'll identify the correct seal kit, motor, or repair part.

Talk to an Expert Call (901) 458-2000

Armstrong Fluid Technology — Frequently Asked Questions

Common questions about Armstrong pumps and repair parts. Contact our team or call (901) 458-2000 for parts identification help.

What is the difference between Armstrong Fluid Technology and Armstrong International?

Armstrong Fluid Technology (Toronto, Canada, founded 1934) makes hydronic circulators, commercial end suction pumps, vertical inline pumps, and pump repair parts for HVAC and plumbing systems. Armstrong International is a separate, unrelated company that makes steam traps, steam pressure reducing valves, and condensate management equipment. Memphis Control Center stocks both — Armstrong Fluid Technology pumps and parts are in our Pumps & Motors category; Armstrong International equipment is in our Temperature Controls category.

How do I find the right Armstrong seal kit for my pump?

The correct seal kit depends on your pump series and motor frame size. For Series 4030, 4280, 4360, 4380 with 143–215 motor frames, the correct kit is in the 8975000-982xx series (1-1/4" seal). For the same pump series with 254–326 frames, a larger seal kit applies. For Series S and H circulators, the correct bearing assembly depends on the specific model: 818254-003K for S-25, 818324-003K for S-35/H-32, 818404-000K for H-41/S-45/S-46, and 818504-000K for S-55, S-57, H-51 through H-54, and 1050 series. Call us at (901) 458-2000 with your pump model number and nameplate HP — we'll identify the correct kit.

What is the Armstrong S-25 pump used for?

The Armstrong S-25 is a close-coupled, 3-piece modular hydronic circulator for closed hot water heating and chilled water systems. Used to circulate water through boilers, fan coil units, heat exchangers, and hydronic terminal units in commercial buildings. The radially-split body allows service without disconnecting piping. Available in cast iron (174031MF-013, heating systems) and bronze/lead-free (174031MF-043, potable water) body configurations. LF (lead-free) versions meet NSF/ANSI 61 for potable water. Flanges sold separately. The S-25 uses the 806026-001K 4-spring coupler (fits S-25, S-34, S-35, H-32, and H-41) — a routine replacement during rebuilds. S-25 bearing assembly replacement is the 818254-003K.

What is the difference between Armstrong Series 4030, 4280, 4360, and 4380?

All four are commercial centrifugal pumps for HVAC and hydronic systems, but differ in configuration. Series 4030 — horizontal end-suction, base-mounted (motor and pump on common base frame). Series 4280 — same but close-coupled without a base frame. Series 4360 and 4380 — vertical inline (suction and discharge in-line; pump mounts in the pipe saving floor space). The 4360 handles flows to 350 GPM and heads to 200 ft. These are the most common configurations in commercial HVAC chilled water and hot water systems.

What does LF mean on Armstrong pump parts?

LF = Lead Free — the part meets NSF/ANSI 61 and NSF/ANSI 372 standards for lead content in products that contact potable (drinking) water. Armstrong LF bronze pump bodies and LF flange kits are required for domestic hot water recirculation, domestic water boosting, and any application where water may be consumed. Non-LF cast iron versions are for closed HVAC heating and cooling systems where the water is not potable.

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