Monarch Motor Powered B Series Pumps
- B50S portable 1/2 HP cast iron utility transfer pump
- Moves 45 GPM at 20 feet of head through 1-1/4 inch ports
- Built-in check valve primes the pump after the first fill
- Many B50S parts share codes with the BE-S50
- Give us the order number and we will check the part
Draining a pool, clearing a flooded basement, or running a garden hose off a rain tank: Monarch built the B50S to be carried to all three jobs. It is the only model we list in the Monarch B Series pump line, and this page is for keeping yours running.
Below you will find what the B50S was built to do, its specs, the parts it shares with other Monarch pumps, and where to go when the job outgrows it.
Keeping a Monarch B50S in Service
We have not confirmed a current replacement for the B50S under the Franklin Electric, Little Giant or Red Lion names. Repair parts are still listed by Monarch code, and several of them match the BE-S50, so a worn B50S can often be rebuilt. Send us your model number and we will confirm the current equivalent.
What the B50S Utility Transfer Pump Was Built For
The B50S is a self-priming utility transfer pump for clean water. Monarch listed it for draining pools and flooded basements, general dewatering, emptying sumps, and running a lawn sprinkler or garden hose.
It ships as one unit with the handle, the cord and a hose adapter, so it is meant to be carried to the job. A large casing chamber and a built-in suction check valve let it re-prime itself after the casing is filled once.
Monarch B Series Pump Specs
| Spec | B50S |
|---|---|
| Order number | 621814 |
| Horsepower and speed | 1/2 HP, 3450 RPM |
| Power | Single phase, 60 Hz, 115/230 volt capacitor start |
| Suction and discharge | 1-1/4" NPT x 1-1/4" NPT |
| Flow at 20 / 30 / 40 feet of head | 45 / 31 / 16 GPM |
| Shut-off head | 50 feet (zero flow) |
| Impeller | Semi-open cast iron |
| Shipping weight | 43 lb |
The curve falls off fast. Flow drops by about two thirds between 20 and 40 feet of head, so the B50S suits short, low lifts rather than long uphill runs.
B50S Parts That Match Other Monarch Pumps
Monarch built the B50S from parts it also used on its BE and BSE pumps. Matching codes from the repair parts lists are shown here.
| Part | B50S code | Same code also listed on |
|---|---|---|
| Casing (yellow) | 438492 | BE50, BE-S50, BE-S75 (Type A) |
| Impeller | 438105 | BE-S50, BSE-S50 |
| Mechanical seal 5/8" | 240104 (Type A) or 240316 (Type B) | BE and BSE series |
| Check valve body and valve rubber | 438415 and 194390 | BE series Type A |
| Motor, 1/2 HP square flange | 204073 | BE-S50, BSE-S50 |
| Cord assembly and handle | 224965 and 438247 | B50S only |
Seals come in Type A and Type B, so check the seal you pull out before you order a new one. If you are not sure, our Monarch parts identification guide shows where to find the codes.
Jobs That Outgrow a 1/2 HP B50S
- More flow or more head. The BSE-S series runs up to 2 HP and 126 GPM at 20 feet.
- Septic effluent. The BE-S series is the effluent version of this pump, with the same yellow casing on the 1/2 and 3/4 HP models.
- A sprinkler system with several zones. A dedicated sprinkler pump builds more pressure than a 1/2 HP transfer pump.
For bigger transfer work, compare the Monarch BSE self-priming pumps. They use the same blind hole impeller idea at higher horsepower.
If the liquid is septic effluent rather than clean water, look at the BE-S self-priming effluent pumps instead.
You can also browse every Monarch motor driven pump from the ACE to the BSEF.
What to Send for a B50S Quote
- The model (B50S) and order number (621814) from the plate.
- The part reference number from the parts diagram, or a photo of the worn part.
- For a seal, whether it is Type A or Type B.
Frequently Asked Questions
What is the difference between a transfer pump and a utility pump?
The difference between a transfer pump and a utility pump is mostly the job. A transfer pump moves liquid from one place to another, such as a pool to a drain or a tank to a trough. A utility pump handles odd jobs where no pump is installed, like a flooded floor. The B50S does both: Monarch called it a utility transfer pump and gave it a handle, an 8-foot cord and a garden hose adapter.
What is the voltage requirement for the B50S Utility Pump?
The voltage requirement for the B50S Utility Pump is single phase, 60 Hz power at 115 or 230 volts. Its 1/2 HP capacitor start motor is listed as 1/60/115/230 in Monarch's order table, and the pump ships with an 8-foot cord assembly (part 224965). Check the wiring diagram on the motor plate to see how your pump is set before you plug it in or rewire it.
Which seal does the B50S take?
The B50S takes a 5/8 inch mechanical seal, listed in two versions: Type A, part 240104, and Type B, part 240316. Compare the old seal to the two types before you order. A seal job on the B50S also calls for a new casing gasket, part 193920. The casing is held on with four 3/8 UNC x 1-1/2 inch bolts, part 120030, with 3/8 spring washers, part 176540.
Send us the B50S model or serial number from the nameplate and we will quote the part or a replacement pump.